[10-18-03] Aviation Safety: Advancements Being Pursued to Improve Airliner Cabin Occupant Safety and Health. GAO-04

[10-18-03] Aviation Safety: Advancements Being Pursued to Improve Airliner Cabin Occupant Safety and Health. GAO-04
United States General Accounting Office
GAO
Report to the Ranking Democratic
Member, Committee on Transportation
and Infrastructure, House of
Representatives
October 2003
AVIATION SAFETY
Advancements Being
Pursued to Improve
Airliner Cabin
Occupant Safety and
Health
GAO-04-33
a
October 2003
AVIATION SAFETY
Highlights of GAO-04-33, a report to the
Ranking Democratic Member, Committee
on Transportation and Infrastructure,
House of Representatives
Airline travel is one of the safest
modes of public transportation in
the United States. Furthermore,
there are survivors in the majority
of airliner crashes, according to the
National Transportation Safety
Board (NTSB). Additionally, more
passengers might have survived if
they had been better protected
from the impact of the crash,
smoke, or fire or better able to
evacuate the airliner. As requested,
GAO addressed (1) the regulatory
actions that the Federal Aviation
Administration (FAA) has taken
and the technological and
operational improvements, called
advancements, that are available or
are being developed to address
common safety and health issues in
large commercial airliner cabins
and (2) the barriers, if any, that the
United States faces in
implementing such advancements.
This report contains
recommendations to FAA to
initiate discussions with NTSB to
facilitate the exchange of medical
information from accident
investigations and to improve the
cost and effectiveness data
available for setting priorities for
research on cabin occupant safety
and health. FAA generally agreed
with the report’s contents and its
recommendations.
www.gao.gov/cgi-bin/getrpt?GAO-04-33.
To view the full product, including the scope
and methodology, click on the link above.
For more information, contact Gerald
Dillingham at (202) 512-2834 or
dillinghamg@gao.gov.
Advancements Being Pursued to Improve
Airliner Cabin Occupant Safety and
Health
FAA has taken a number of regulatory actions over the past several decades
to address safety and health issues faced by passengers and flight attendants
in large commercial airliner cabins. GAO identified 18 completed actions,
including those that require safer seats, cushions with better fire-blocking
properties, better floor emergency lighting, and emergency medical kits.
GAO also identified 28 advancements that show potential to further improve
cabin safety and health. These advancements vary in their readiness for
deployment. Fourteen are mature, currently available, and used in some
airliners. Among these are inflatable lap seat belts, exit doors over the wings
that swing out on hinges instead of requiring manual removal, and photoluminescent floor lighting. The other 14 advancements are in various stages
of research, engineering, and development in the United States, Canada, or
Europe.
Several factors have slowed the implementation of airliner cabin safety and
health advancements. For example, when advancements are ready for
commercial use, factors that may hinder their implementation include the
time it takes for (1) FAA to complete the rule-making process, (2) U.S. and
foreign aviation authorities to resolve differences between their respective
requirements, and (3) the airlines to adopt or install advancements after FAA
has approved their use. When advancements are not ready for commercial
use because they require further research, FAA’s processes for setting
research priorities and selecting research projects may not ensure that the
limited federal funding for cabin safety and health research is allocated to
the most critical and cost-effective projects. In particular, FAA does not
obtain autopsy and survivor information from NTSB after it investigates a
crash. This information could help FAA identify and target research to the
primary causes of death and injury. In addition, FAA does not typically
perform detailed analyses of the costs and effectiveness of potential cabin
occupant safety and health advancements, which could help it identify and
target research to the most cost-effective projects.
A Survivable Large Commercial Airliner Accident
Contents
Letter
1
3
7
Results in Brief Background
Regulatory Actions Have Been Taken and Additional Advancements Are Under Way to Improve Cabin Occupants’ Safety and Health
Several Factors Have Slowed the Implementation of Cabin
Occupant Safety and Health Advancements
Conclusions
Recommendations for Executive Action
Agency Comments and Our Evaluation
19
28
29
30
Objectives, Scope, and Methodology
31
Canada and Europe Cabin Occupant Safety and Health Responsibilities
Canada
Europe
35
35
36
Summary of Key Actions FAA Has Taken to Improve Airliner Cabin Safety and Health Since 1984
40
9
Appendixes
Appendix I:
Appendix II:
Appendix III:
Appendix IV:
Appendix V:
Appendix VI:
Summaries of Potential Impact Safety Advancements
Retrofitting All Commercial Aircraft with More Advanced Seats
Improving the Ability of Airplane Floors to Hold Seats in an
Accident
Preventing Overhead Storage Bin Detachment to Protect Passengers
in an Accident
Child Safety Seats
Inflatable Lap Belt Air Bags
43
43
48
50
52
56
Summaries of Potential Fire Safety Advancements
Fuel Tank Inerting
Arc Fault Circuit Breaker
Multisensor Detectors
Water Mist Fire Suppression
Fire-Safe Fuels
Thermal Acoustic Insulation Materials
Ultra-Fire-Resistant Polymers
Airport Rescue and Fire-Fighting Operations
58
58
62
64
67
71
73
76
79
Summaries of Potential Improved Evacuation Safety
Advancements
82
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Contents
Passenger Safety Briefings
Exit Seat Briefing
Photo-luminescent Floor Track Marking
Crewmember Safety and Evacuation Training
Acoustic Attraction Signals
Smoke Hoods
Exit Slide Testing
Overwing Exit Doors
Next Generation Evacuation Equipment and Procedures
Personal Flotation Devices
Appendix VII: Summaries of General Cabin Occupant Safety and Health
Advancements
Advanced Warnings of Turbulence
Preparations for In-flight Medical Emergencies
Reducing Health Risks to Passengers with Certain Medical
Conditions
Improved Awareness of Radiation Exposure
Occupational Safety and Health Standards for Flight
Attendants
Appendix VIII: Application of a Cost Analysis Methodology to Inflatable Lap
Belts
Inflatable Lap Belts
Summary of Results
Methodology
Appendix IX: GAO Contacts and Staff Acknowledgments
GAO Contacts
Staff Acknowledgments
Tables
Table 1: Regulatory Actions Taken by FAA to Improve Cabin
Occupant Safety and Health Since 1984
Table 2: Advancements with Potential to Improve Cabin Occupant Safety and Health
Table 3: Status of 10 Significant FAA Rules Pertaining to Airliner Cabin Occupants’ Safety and Health, Fiscal Year 1995
through September of Fiscal Year 2003
Table 4: Costs to Equip an Average-sized Airplane in the U.S. Fleet with Inflatable Lap Seat Belts, Estimated under Alternative Scenarios (In 2002 discounted dollars)
Table 5: Key Assumptions
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4
4
20
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Contents
Figures
Figure 1: Inflatable Lap Belt Air Bag Inflation Sequence
Figure 2: Manual “Self Help” and “Swing Out” Over-Wing Exits Figure 3: Funding for Federal Research on Cabin Occupant Safety and Health Issues, by Facility, Fiscal Years 2000-2005
Figure 4: Allocation of Federal Funding for Aircraft Cabin Occupant Safety and Health Research, Fiscal Year 2003
Figure 5: Coach Seating and Impact Position in Coach Seating
Figure 6: Examples of Child Safety Seats
Figure 7: Water Mist Nozzle and Possible Placement
Figure 8: Fire Insulation Blankets
Figure 9: Flammable Cabin Materials and Small-scale Material Test Device
Figure 10: Airport Rescue and Fire Training
Figure 11: Airline Briefing to Passengers on Safety Briefing
Cards
Figure 12: Floor Track Marking Using Photo-luminescent
Materials
Figure 13: Test Installation of Acoustic Signalling Device
Figure 14: An Example of a Commercially Available Smoke Hood
Figure 15: Drawing of Possible Emergency Slide Testing of FAA’s 747
Test Aircraft
Figure 16: Airbus’ Planned Double Deck Aircraft
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Contents
Abbreviations
ACRM
CAMI
CRM
DGAC
DOT
DOT IG
DVT
EASA
FAA
ICAO
JAA
NASA
NIOSH
NTSB
OSHA
TRL
TSO
Advanced Crew Resource Management
Civil Aerospace Medical Institute
Crew Resource Management
Direction Générale de l’Aviation Civile
Department of Transportation
Department of Transportation’s Inspector General
deep vein thrombosis
European Aviation Safety Agency
Federal Aviation Administration
International Civil Aviation Organization European Joint Aviation Authorities
National Aeronautics and Space Administration
National Institute of Safety and Health
National Transportation Safety Board
Occupational Health and Safety Administration
Technical Readiness Level
Technical Standing Order
This is a work of the U.S. government and is not subject to copyright protection in the
United States. It may be reproduced and distributed in its entirety without further
permission from GAO. However, because this work may contain copyrighted images or
other material, permission from the copyright holder may be necessary if you wish to
reproduce this material separately.
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GAO-04-33 Airliner Cabin Occupant Safety and Health
A
United States General Accounting Office
Washington, D.C. 20548
October 3, 2003
The Honorable James L. Oberstar
Ranking Democratic Member
Committee on Transportation
and Infrastructure
House of Representatives
Dear Mr. Oberstar:
Airline travel is one of the safest modes of public transportation in the
United States, in large part because of the Congress’s, Federal Aviation
Administration’s (FAA), commercial airlines’, aircraft manufacturers’, and
airports’ combined efforts to prevent commercial airliner accidents.
Furthermore, although a few airliner accidents are catastrophic, there are
survivors in a majority of crashes. According to the National
Transportation Safety Board (NTSB), passengers survived in 19 of the 26
U.S. large commercial airliner accidents that occurred from 1982 through
2001, and in these 19 accidents, over 76 percent of the passengers (1,523 of
1,988) survived.1 Additionally, some of the passengers who died in these
accidents might have survived if they had been better protected from the
impact of the crash or from the effects of smoke and fire and had been
better able to evacuate the airliner. This possibility of survival has led
federal safety officials to focus their efforts not only on preventing airliner
accidents, but also on increasing the chances of surviving them.
Over the past several decades, FAA has been taking regulatory actions to
require the implementation of technological and operational improvements
in cabin occupant safety and health to help increase passengers’ chances of
surviving large commercial airliner accidents. In addition, FAA and the
aviation community have been conducting research on new technological
and operational improvements, which we refer to in this report as
advancements, whose implementation could further increase passengers’
chances of survival and improve the safety and health of passengers and
flight attendants. This report discusses regulatory actions that FAA has
taken as well as potential advancements in cabin occupant safety and
health that are (1) currently available but not yet implemented or installed,
and (2) not yet available and subject to additional research to advance the
1
Large, or ‘transport category’ commercial aircraft are defined as those with a capacity of 30
or more passengers or a load of 7,500 pounds or more.
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GAO-04-33 Airliner Cabin Occupant Safety and Health
technology or lower costs. For implementation of these advancements to
occur, FAA often has to take regulatory action, that is, issuing regulations
or airworthiness directives that require the implementation of
technological and operational improvements in cabin occupant safety and
health. FAA continues to pursue regulatory initiatives as well as conduct
research to improve cabin occupant safety and health. The aviation
community is also attempting to enhance the safety and health of those
traveling and working in airliner cabins through such measures as
providing earlier warnings of turbulence and information on the potential
to develop blood clots on long-distance flights. Besides increasing cabin
occupants’ safety and health, these actions and efforts could benefit the
airlines by helping to restore passengers’ confidence in the safety of flight
and thereby increasing the demand for air travel, which fell sharply after
September 11, 2001, and still remains below fiscal year 2000 levels.
In response to your request, this report addresses the following questions:
(1) What regulatory actions has FAA taken, and what key advancements
are available or being developed by FAA and others to address safety and
health issues faced by passengers and flight attendants in large commercial
airliner cabins? (2) What factors, if any, slow the implementation of
advancements in cabin occupant safety and health? In addition, as
requested, we identified some factors faced by Canada and Europe in their
efforts to improve cabin occupant safety and health (see app. II).
To identify the regulatory actions FAA has taken and the key advancements
that are available or being developed to address safety and health issues
facing passengers and flight attendants (cabin occupants), we reviewed the
relevant literature, interviewed FAA officials, and reviewed FAA’s
documentation on the regulatory actions it has taken to enhance cabin
occupant safety and health. As part of this effort, FAA officials identified
key regulatory actions that had been completed in this area. In addition, we
interviewed other aviation safety experts in government, industry, and
academia from the United States, Canada, and Europe. (See app. I for
additional information.) Through our reviews and interviews, we found
that FAA’s regulatory actions and advancements fell into four broad
categories—three related to safety in the event of a crash and one related
to general cabin occupant safety and health. The regulatory actions and
advancements related to safety in the event of a crash are those actions
taken to (1) minimize injuries from the impact of a crash, (2) prevent fire or
mitigate its effects, and (3) improve the chances and speed of evacuation.
In addition, we discuss the regulatory actions and advancements FAA has
taken to address a fourth category—improving the safety and health of
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GAO-04-33 Airliner Cabin Occupant Safety and Health
cabin occupants. Using the results of our reviews and interviews, we
identified and categorized 28 advancements that are currently available or
being developed, including 5 impact advancements, 8 fire advancements,
10 evacuation advancements, and 5 cabin occupant safety and health
advancements. For each of these advancements, we discuss the
background, research, and regulatory status.2 We also discuss each
advancement’s technological readiness for use in the existing commercial
airliner fleet or in newly produced commercial airplanes. To identify
factors that have slowed implementation of airliner cabin occupant safety
and health advancements, we interviewed FAA, NTSB, and industry
officials. In addition, we analyzed documentation from FAA, NTSB, and
aviation safety experts to identify factors relating to key issues within FAA
and the aviation community related to prioritizing and funding research,
choosing advancements for regulatory implementation, and gaining the
aviation community’s acceptance of these advancements.
This report does not address cabin air quality because we are doing work in
this area for another congressional requester. In addition, given the large
scope of this review, the report does not focus on safety and health issues
for flight deck crews (pilots and flight engineers) since they face some
unique issues not faced by cabin occupants. It also does not address
aviation security issues, such as hijackings, sabotage, or terrorist activities.
We conducted our review from January 2002 through September 2003 in
accordance with generally accepted government auditing standards.
Results in Brief
FAA has taken a number of key regulatory actions over the past several
decades to improve the safety and health of passengers and flight
attendants in large commercial airliner cabins. We identified 18 such
completed regulatory actions that FAA has taken since 1984. Table 1 shows
the number of such actions by category and provides an example for each
category of action.
2
In identifying 28 advancements, we are not suggesting that these are the only advancements
being pursued, rather that these advancements have been recognized by aviation safety
experts we contacted as offering promise for improving the safety and health of cabin
occupants.
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Table 1: Regulatory Actions Taken by FAA to Improve Cabin Occupant Safety and
Health Since 1984
Category of regulatory action
Example
Number of key
actions taken
Minimize injuries from the impact Stronger seats
of a crash
2
Prevent fire or mitigate its effects Fire-blocking seat cushions
7
Improve the chances and speed
of evacuation
Emergency floor lighting
6
Improve the safety and health of
cabin occupants
Onboard emergency medical
kits
3
Source: GAO.
We also identified 28 advancements that have the potential to increase the
chances of surviving a commercial airliner crash and to improve the safety
and health of cabin occupants—both passengers and flight attendants.
Table 2 shows the number of such advancements by category and provides
an example for each.
Table 2: Advancements with Potential to Improve Cabin Occupant Safety and Health
Number of key
advancements
Category of advancement
Example
Minimize injuries from the impact of
a crash
Lap seat belts with inflatable air
bags
5
Prevent fire or mitigate its effects
Reduced fuel tank flammability
8
Improve the chances and speed of
evacuation
Improved passenger safety
briefings
Improve the safety and health of
cabin occupants
Advanced warnings of
turbulence
10
5
Source: GAO.
These 28 advancements vary in their readiness for deployment. For
example, 14 of the technologies are currently available but not yet
implemented or installed. Two of these, preparation for in-flight medical
emergencies and improved insulation, were addressed through separate
regulations. These regulations require airlines to install additional
emergency medical equipment (automatic external defibrillators and
enhanced emergency medical kits) by 2004, replace flammable insulation
(metalized Mylar®) with improved insulation by 2005, and manufacture
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GAO-04-33 Airliner Cabin Occupant Safety and Health
new large commercial airliners with improved (thermal acoustic)
insulation beginning September 2, 2005. Another currently available
advancement is in FAA’s rule-making process—retrofitting the entire
existing fleet with significantly stronger seats. These seats, commonly
referred to as 16g seats, for example, can withstand the force of an impact
16 times a passenger’s body weight (16g), rather than 9 times (9g), as
currently required primarily for new generation commercial aircraft.3 For
the remaining 11 currently available advancements, while FAA does not
require their use, some are being used by selected airlines. For example,
some airlines have elected to use inflatable lap seat belts, exit doors over
the wings that swing out on hinges instead of requiring manual removal,
and photo-luminescent floor lighting.4 In addition, some of these
advancements are available for purchase by the flying public, including
smoke hoods and child safety seats certified for use on commercial
airliners. The remaining 14 advancements are in various stages of research,
engineering, and development in the United States, Canada, or Europe.
Several factors slow the implementation of advancements in cabin
occupant safety and health, including those that are currently available, but
have not yet been implemented or installed and those that require further
research to demonstrate their effectiveness or lower their costs before they
are ready for implementation. For those that are ready, and for which
design and certification standards have been developed, FAA may
undertake the rule-making process to require their implementation. As our
prior work has shown, this process can take years. In addition, FAA and its
international counterparts attempt to reach agreement on, or harmonize,
their requirements for aviation procedures and equipment. The authorities’
current harmonization process has resulted in a backlog, which has slowed
the implementation of several cabin occupant safety and health
advancements. Finally, the airlines must implement the advancements.
While some advancements, such as improved safety briefings, can be
implemented quickly and economically, others, such as retrofitting
commercial aircraft with stronger passenger seats, require time3
A separate rule-making effort in 1988 required that newly manufactured aircraft be
equipped with stronger, 16g seats; however, it did not require that the existing U.S. fleet of
commercial aircraft be retrofitted with these seats.
4
FAA officials told us that using photo-luminescent lighting is a different way to meet an
existing standard and, therefore, should not be considered an advancement in safety.
However, because photo-luminescent floor lighting differs from standard floor lighting in
that it works without electricity, some in the aviation community consider it a safety
advancement.
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GAO-04-33 Airliner Cabin Occupant Safety and Health
consuming, costly changes. FAA may give the airlines several years to
retrofit their fleets in order to coordinate the change, when possible, with
existing maintenance schedules and allow the airlines to absorb the
associated costs. For advancements that require further research before
they can be considered for use, FAA’s multistep process for identifying
potential cabin occupant safety and health research projects and allocating
its limited resources to research projects on the advancements is hampered
by a lack of autopsy and survivor information and cost and effectiveness
data. According to FAA researchers, they have not had adequate access to
autopsy reports and certain survivor information that NTSB obtains from
autopsy reports and interviews with survivors during its investigations of
commercial airliner accidents. This information could help FAA to identify
the principal causes of death and injury and the major factors affecting
survival, and to target research to advancements addressing these critical
causes and factors. NTSB told us that while they provide large amounts of
information on the causes of death and injury in information they make
publicly available, they would consider making this additional information
available to FAA if steps were taken to safeguard the privacy of victims and
survivors. FAA’s multistep process for selecting research projects on
advancements includes consideration of such factors as their potential
impact on accident prevention and accident mitigation; however, it does
not include developing comparable estimates of cost and effectiveness for
competing advancements to allow direct comparisons between them on
their potential to reduce injuries and deaths. We developed a cost analysis
methodology to illustrate how FAA could develop comparable cost
estimates, to enhance its current process. The results of such analyses
could be combined with similar estimates of effectiveness using data
available from a variety of sources, including industry and academia. Using
comparable cost and effectiveness data across the range of advancements
could position the agency to choose more effectively between competing
advancements, taking into account estimates of the number of injuries and
fatalities that each advancement might prevent for the dollars invested.
Such cost and effectiveness data would provide a valuable supplement to
FAA’s current process for setting research priorities and selecting projects
for funding.
This report contains a recommendation to the Secretary of Transportation
to direct the FAA Administrator to initiate discussions with NTSB to
facilitate the exchange of medical information from accident
investigations. In addition, the report contains a recommendation to the
FAA Administrator to improve the analyses available to decision makers
responsible for setting research priorities and selecting projects for
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improving the safety and health of cabin occupants by (1) developing
comparable cost estimates of potential advancements competing for
funding and (2) developing or collecting data on the effectiveness of each
potential advancement to reduce injuries or fatalities. In commenting on a
draft of this report, FAA said that they generally agreed with the report’s
contents and its recommendations.
Background
The safe travel of U.S. airline passengers is a joint responsibility of FAA and
the airlines in accordance with the Federal Aviation Act of 1958, as
amended, and the Department of Transportation Act, as amended. To carry
out its responsibilities under these acts, FAA supports research and
development; certifies that new technologies and procedures are safe;
undertakes rule-makings, which when finalized form the basis of federal
aviation regulations; issues other guidance, such as Advisory Circulars; and
oversees the industry’s compliance with standards that aircraft
manufacturers and airlines must meet to build and operate commercial
aircraft. Aircraft manufacturers are responsible for designing aircraft that
meet FAA’s safety standards, and air carriers are responsible for operating
and maintaining their aircraft in accordance with the standards for safety
and maintenance established in FAA’s regulations. FAA, in turn, certifies
aircraft designs and monitors the industry’s compliance with the
regulations.
FAA’s general process for issuing a regulation, or rule, includes several
steps. When the regulation would require the implementation of a
technology or operation, FAA first certifies that the technology or
operation is safe. Then, FAA publishes a notice of proposed rule-making in
the Federal Register, which sets forth the terms of the rule and establishes
a period for the public to comment on it. Next, FAA reviews the comments
by incorporating changes into the rule that it believes are warranted, and,
in some instances, it repeats these steps one or more times. Finally, FAA
publishes a final rule in the Federal Register. The final rule includes the
date when it will go into effect and a time line for compliance.
Within FAA, the Aircraft Certification Service is responsible for certifying
that technologies are safe, including improvements to cabin occupant
safety and health, generally through the issuance of new regulations, a
finding certifying an equivalent level of safety, or a special condition when
no rule covers the new technology. The Certification Service is also
responsible for taking enforcement action to ensure the continued safety of
aircraft by prescribing standards for aircraft manufacturers governing the
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design, production, and airworthiness of aeronautical products, such as
cabin interiors. The Flight Standards Service is primarily responsible for
certifying an airline’s operations (assessing the airline’s ability to carry out
its operations and maintain the airworthiness of the aircraft) and for
monitoring the operations and maintenance of the airline’s fleet.
FAA conducts research on cabin occupant safety and health issues in two
research facilities, the Mike Monroney Aeronautical Center/Civil
Aerospace Medical Institute in Oklahoma City, Oklahoma, and the William
J. Hughes Technical Center in Atlantic City, New Jersey. The institute
focuses on the impact of flight operations on human health, while the
technical center focuses on improvements in aircraft design, operation, and
maintenance and inspection to prevent accidents and improve survivability.
For the institute or the technical center to conduct research on a project,
an internal FAA requester must sponsor the project. For example, FAA’s
Office of Regulation and Certification sponsors much of the two facilities’
work in support of FAA’s rule-making activities. FAA also cooperates on
cabin safety research with the National Aeronautics and Space
Administration (NASA), academic institutions, and private research
organizations.
Until recently, NASA conducted research on airplane crashworthiness at its
Langley Research Center in Hampton, Virginia. However, because of
internal budget reallocations and a decision to devote more of its funds to
aviation security, NASA terminated the Langley Center’s research on the
crashworthiness of commercial aircraft in 2002. NASA continues to
conduct fire-related research on cabin safety issues at its Glenn Research
Center in Cleveland, Ohio.
NTSB has the authority to investigate civil aviation accidents and collects
data on the causes of injuries and death for the victims of commercial
airliner accidents. According to NTSB, the majority of fatalities in
commercial airliner accidents are attributable to crash impact forces and
the effects of fire and smoke. Specifically, 306 (66 percent) of the 465
fatalities in partially survivable U.S. aviation accidents from 1983 through
2000 died from impact forces, 131 (28 percent) died from fire and smoke,
and 28 (6 percent) died from other causes.5
5
NTSB, Survivability of Accidents Involving Part 121 U.S. Air Carrier Operations, 1983
Through 2000, NTSB/SR-01/01.
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Surviving an airplane crash depends on a number of factors. The space
surrounding a passenger must remain large enough to prevent the
passenger from being crushed. The force of impact must also be reduced to
levels that the passenger can withstand, either by spreading the impact
over a larger part of the body or by increasing the duration of the impact
through an energy-absorbing seat or fuselage. The passenger must be
restrained in a seat to avoid striking the interior of the airplane, and the
seat must not become detached from the floor. Objects within the airplane,
such as debris, overhead luggage bins, luggage, and galley equipment, must
not strike the passenger. A fire in the cabin must be prevented, or, if one
does start, it must burn slowly enough and produce low enough levels of
toxic gases to allow the passenger to escape from the airplane. If there is a
fire, the passenger must not have sustained injuries that prevent him or her
from escaping quickly. Finally, if the passenger escapes serious injury from
impact and fire, he or she must have access to exit doors and slides or
other means of evacuation.
Regulatory Actions
Have Been Taken and
Additional
Advancements Are
Under Way to Improve
Cabin Occupants’
Safety and Health
Over the past several decades, FAA has taken a number of regulatory
actions designed to improve the safety and health of airline passengers and
flight attendants by (1) minimizing injuries from the impact of a crash, (2)
preventing fire or mitigating its effects, (3) improving the chances and
speed of evacuation, or (4) improving the safety and health of cabin
occupants. (See app. III for more information on the regulatory actions
FAA has taken to improve cabin occupant safety and health.) Specifically,
we identified 18 completed regulatory actions that FAA has taken since
1984. In addition to these past actions, FAA and others in the aviation
community are pursuing advancements in these four areas to improve
cabin occupant safety and health in the future. We identified and reviewed
28 such advancements—5 to reduce the impact of a crash on occupants, 8
to prevent or mitigate fire and its effects, 10 to facilitate evacuation from
aircraft, and 5 to address general cabin occupant safety and health issues.
Minimizing Injuries from the
Impact of a Crash The primary cause of injury and death for cabin occupants in an airliner
accident is the impact of the crash itself. We identified two key regulatory
actions that FAA has taken to better protect passengers from impact
forces. For example, in 1988, FAA required stronger passenger seats for
newly manufactured commercial airplanes to improve protection in
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survivable crashes.6 These new seats are capable, for example, of
withstanding an impact force that is approximately 16 times a passenger’s
body weight (16g), rather than 9 times (9g), and must be tested dynamically
(in multiple directions to simulate crash conditions), rather than statically
(e.g., drop testing to assess the damage from the force of the weight alone
without motion). In addition, in 1992, FAA issued a requirement for
corrective action (airworthiness directive) for designs found not to meet
the existing rules for overhead storage bins on certain Boeing aircraft, to
improve their crashworthiness after bin failures were observed in the 1989
crash of an airliner in Kegworth, England, and a 1991 crash near
Stockholm, Sweden.
We also identified five key advancements that are being pursued to provide
cabin occupants with greater impact protection in the future. These
advancements are either under development or currently available.
Examples include the following:
• Lap seat belts with inflatable air bags: Lap seat belts that contain
inflatable air bags have been developed by private companies and are
currently available to provide passengers with added protection during
a crash. About 1,000 of these lap seat belts have been installed on
commercial airplanes, primarily in the seats facing wall dividers
(bulkheads) to prevent passengers from sustaining head injuries during
a crash. (See fig. 1.)
• Improved seating systems: Seat safety depends on several interrelated
systems operating properly, and, therefore, an airline seat is most
accurately discussed as a system. New seating system designs are being
developed by manufacturers to incorporate new safety and aesthetic
designs as well as meet FAA’s 16g seat regulations to better protect
passengers from impact forces. These seating systems would help to
ensure that the seats themselves perform as expected (i.e., they stay
attached to the floor tracks); the space between the seats remains
adequate in a crash; and the equipment in the seating area, such as
phones and video screens, does not increase the impact hazard.
6
FAA subsequently proposed, in October 2002, that the 16g seats be put into the entire
existing fleet for both passengers and flight attendants within 14 years to better protect
passengers from impact forces. We included this proposal in our list of advancements.
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• Child safety seats: Child safety seats could provide small children with
additional protection in the event of an airliner crash. NTSB and others
have recommended their use, and FAA has been involved in this issue
for at least 15 years. While it has used its rule-making process to
consider requiring their use, FAA decided not to require child safety
restraints because its analysis found that if passengers were required to
pay full fare for children under the age of 2, some parents would choose
to travel by automobile and, statistically, the chances would increase
that both the children and the adults would be killed. FAA is continuing
to consider a child safety seat requirement.
Figure 1: Inflatable Lap Belt Air Bag Inflation Sequence
Appendix IV contains additional information on the impact advancements
we have identified.
Preventing Fire or
Mitigating Its Effect
Fire prevention and mitigation efforts have given passengers additional
time to evacuate an airliner following a crash or cabin fire. FAA has taken
seven key regulatory actions to improve fire detection, eliminate potential
fire hazards, prevent the spread of fires, and better extinguish them. For
example, to help prevent the spread of fire and give passengers more time
to escape, FAA upgraded fire safety standards to require that seat cushions
have fire-blocking layers, which resulted in airlines retrofitting 650,000
seats over a 3-year period. The agency also set new low heat/smoke
standards for materials used for large interior surfaces (e.g., sidewalls,
ceilings, and overhead bins), which FAA officials told us resulted in a
significant improvement in postcrash fire survivability. FAA also required
smoke detectors to be placed in lavatories and automatic fire extinguishers
in lavatory waste receptacles in 1986 and 1987, respectively. In addition, the
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agency required airlines to retrofit their fleets with fire detection and
suppression systems in cargo compartments, which according to FAA,
applied to over 3,700 aircraft at a cost to airlines of $300 million. To better
extinguish fires when they do start, FAA also required, in 1985, that
commercial airliners carry two Halon fire extinguishers in addition to other
required extinguishers because of Halon’s superior fire suppression
capabilities.
We also identified 8 key advancements that are currently available and
awaiting implementation or are under development to provide additional
fire protection for cabin occupants in the future. Examples include the
following:
• Reduced flammability of insulation materials: To eliminate a potential
fire hazard, in May 2000, FAA required that air carriers replace
insulation blankets covered with a type of insulation known as
metalized Mylar® on specific aircraft by 2005, after it was found that the
material had ignited and contributed to the crash of Swiss Air Flight
111.7 Over 700 aircraft were affected by this requirement. In addition,
FAA issued a rule in July 2003 requiring that large commercial airplanes
manufactured after September 2, 2005, be equipped with thermal
acoustic insulation designed to an upgraded fire test standard that will
reduce the incidence and intensity of in-flight fires. In addition, after
September 2, 2007, newly manufactured aircraft must be equipped with
thermal acoustic materials designed to meet a new standard for burnthrough resistance, providing passengers more time to escape during a
postcrash fire.
• Reduced fuel tank flammability: Flammable vapors in aircraft fuel
tanks can ignite. However, currently available technology can greatly
reduce this hazard by “blanketing” the fuel tank with nonexplosive
nitrogen-enriched air to suppress (“inert”) the potential for explosion of
the tank. The U.S. military has used this technology on selected aircraft
for 20 years, but U.S. commercial airlines have not adopted the
technology because of its cost and weight. FAA officials told us that the
military’s technology was also unreliable and designed to meet military
rather than civilian airplane design requirements. FAA fire safety
experts have developed a lighter-weight inerting system for center fuel
tanks, which is simpler than the military system and potentially more
7
Affected aircraft included Boeing MD-80, MD-88, MD-90, DC-10, and MD-11.
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reliable. Reliability of this technology is a major concern for the aviation
industry. According to FAA officials, Boeing and Airbus began flight
testing this technology in July 2003 and August 2003, respectively.8 In
addition, the Air Transport Association (ATA) noted that inerting is only
one prospective component of an ongoing major program for fuel tank
safety, and that it has yet to be justified as feasible and cost-effective.
• Sensor technology: Sensors are currently being developed to better
detect overheated or burning materials. According to FAA and the
National Institute of Standards and Technology, many current smoke
and fire detectors are not reliable. For example, a recent FAA study
reported at least one false alarm per week in cargo compartment fire
detection systems. The new detectors are being developed by Airbus
and others in private industry to reduce the number of false alarms. In
addition, FAA is developing standards that would be used to approve
new, reduced false alarm sensors. NASA is also developing new sensors
and detectors.
• Water mist for extinguishing fires: Technology has been under
development for over two decades to dispense water mist during a fire
to protect passengers from heat and smoke and prevent the spread of
fire in the cabin. The most significant development effort has been made
by a European public-private consortium, FIREDETEX, with over 5
million euros of European Community funding and a total project cost
of over 10 million euros (over 10 million U.S. dollars). The development
of this system was prompted, in part, by the need to replace Halon,
when it was determined that this main firefighting agent used in fire
extinguishers aboard commercial airliners depletes ozone in the
atmosphere.
Appendix V contains additional information on advancements that address
fire prevention and mitigation.
Improving the Chances and
Speed of Evacuation
Enabling passengers to evacuate more quickly during an emergency has
saved lives. Over the past two decades, FAA has completed regulatory
action on the following six key requirements to help speed evacuations:
8
According to FAA, Boeing is flight testing a system similar to the FAA design, and Airbus is
flight testing the FAA system in an A320. Boeing announced that it would begin installing
inerting systems similar to the FAA design in their 747s in 2005.
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• Improve access to certain emergency exits, such as those generally
smaller exits above the wing, by providing an unobstructed passageway
to the exit.
• Install public address systems that are independently powered and can
be used for at least 10 minutes.
• Help to ensure that passengers in the seats next to emergency exits are
physically and mentally able to operate the exit doors and assist other
passengers in emergency evacuations.
• Limit the distance between emergency exits to 60 feet.
• Install emergency lighting systems that visually identify the emergency
escape path and each exit.
• Install fire-resistant emergency evacuation slides.
We also identified 10 advancements that are either currently available but
awaiting implementation or require additional research that could lead to
improved aircraft evacuation, including the following:
• Improved passenger safety briefings: Information is available to the
airlines on how to develop more appealing safety briefings and safety
briefing cards so that passengers would be more likely to pay attention
to the briefings and be better prepared to evacuate successfully during
an emergency. Research has found that passengers often ignore the oral
briefings and do not familiarize themselves with the safety briefing
cards. FAA has requested that air carriers explore different ways to
present safety information to passengers, but FAA regulates only the
content of briefings. The presentation style of safety briefings is left up
to air carriers.
• Over-wing exit doors: Exit doors located over the wings of some
commercial airliners have been redesigned to “swing out” and away
from the aircraft so that cabin occupants can exit more easily during an
emergency. Currently, the over-wing exit doors on most U.S. commercial
airliners are “self help” doors and must be lifted and stowed by a
passenger, which can impede evacuation. (See fig. 2.) The redesigned
doors are now used on new-generation B-737 aircraft operated by one
U.S. and most European airlines. FAA does not currently require the use
of over-wing exit doors that swing out because the exit doors that are
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removed manually meet the agency’s safety standards. However, FAA is
working with the Europeans to develop common requirements for the
use of this type of exit door.
• Audio attraction signals: The United Kingdom’s Civil Aviation
Authority and the manufacturer are testing audio attraction signals to
determine their usefulness to passengers in locating exit doors during
an evacuation. These signals would be mounted near exits and activated
during an emergency. The signals would help the passengers find the
nearest exit even if lighting and exit signs were obscured by smoke.
Figure 2: Manual “Self Help” and “Swing Out” Over-Wing Exits
Appendix VI contains additional information on advancements to improve
aircraft emergency evacuations.
Improving the Safety and
Health of Cabin Occupants Passengers and flight attendants can face a range of safety and health
effects while aboard commercial airliners. We identified three key actions
taken by FAA to help maintain the safety and health of passengers and the
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cabin crew during normal flight operations.9 For example, to prevent
passengers from being injured during turbulent conditions, FAA initiated
the Turbulence Happens campaign in 2000 to increase public awareness of
the importance of wearing seatbelts. The agency has advised the airlines to
warn passengers to fasten their seatbelts when turbulence is expected, and
the airlines generally advise or require passengers to keep their seat belts
fastened while seated to help avoid injuries from unexpected turbulence.
FAA has also required the airlines to equip their fleets with emergency
medical kits since 1986. In addition, Congress banned smoking on most
domestic flights in 1990.
We also identified five advancements that are either currently available but
awaiting implementation or require additional research that could lead to
an improvement in the health of passengers and flight attendants in the
future.
• Automatic external defibrillators: Automatic external defibrillators are
currently available for use on some commercial airliners if a passenger
or crew member requires resuscitation. In 1998, the Congress directed
FAA to assess the need for the defibrillators on commercial airliners. On
the basis of its findings, the agency issued a rule requiring that U.S.
airlines equip their aircraft with automatic external defibrillators by
2004. According to ATA, most airlines have already done so.
• Enhanced emergency medical kits: In 1998, the Congress directed FAA
to collect data for 1 year on the types of in-flight medical emergencies
that occurred to determine if existing medical kits should be upgraded.
On the basis of the data collected, FAA issued a rule that required the
contents of existing emergency medical kits to be expanded to deal with
a broader range of emergencies. U.S. commercial airliners are required
to carry these enhanced emergency medical kits by 2004. Most U.S.
airlines have already completed this upgrade, according to ATA.
• Advance warning of turbulence: New airborne weather radar and other
technologies are currently being developed and evaluated to improve
the detection of turbulence and increase the time available to cabin
occupants to avert potential injuries. FAA’s July 2003 draft strategic plan
established a performance target of reducing injuries to cabin occupants
caused by turbulence. To achieve this objective, FAA plans to continue
9
As noted, actions taken to improve cabin air quality will be discussed in another report.
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evaluating new airborne weather radars and other technologies that
broadly address weather issues, including turbulence. In addition, the
draft strategic plan set a performance target of reducing serious injuries
caused by turbulence by 33 percent by fiscal year 2008--using the
average for fiscal years 2000 through 2002 of 15 injuries per year as the
baseline and reducing this average to no more than 10 per year.
• Improve awareness of radiation exposure: Flight attendants and
passengers who fly frequently can be exposed to higher levels of
radiation on a cumulative basis than the general public. High levels of
radiation have been linked to an increased risk of cancer and potential
harm to fetuses. To help passengers and crew members estimate their
past and future radiation exposure levels, FAA developed a computer
model, which is publicly available on its Web site
http://www.jag.cami.jccbi.gov/cariprofile.asp. However, the extent to
which flight attendants and frequent flyers are aware of cosmic
radiation’s risks and make use of FAA’s computer model is unclear.
Agency officials told us that they plan to install a counter capability on
its Civil Aerospace Medical Institute Web site to track the number of
visits to its aircrew and passenger health and safety Web site. FAA also
plans to issue an Advisory Circular by early next year, which
incorporates the findings of a just completed FAA report, “What
Aircrews Should Know About Their Occupational Exposure to Ionizing
Radiation.” This Advisory Circular will include recommended actions
for aircrews and information on solar flare event notification of
aircrews. In contrast, airlines in Europe abide by more stringent
requirements for helping to ensure that cabin and flight crew members
do not receive excessive doses of radiation from performing their flight
duties during a given year. For example, in May 1996, the European
Union issued a directive for workers, including air carrier crew
members (cabin and flight crews) and the general public, on basic safety
and health protections against dangers arising from ionizing radiation.
This directive set dose limits and required air carriers to (1) assess and
monitor the exposure of all crew members to avoid exceeding exposure
limits, (2) work with those individuals at risk of high exposure levels to
adjust their work or flight schedules to reduce those levels, and (3)
inform crew members of the health risks that their work involves from
exposure to radiation. It also required airlines to work with female crew
members, when they announce a pregnancy, to avoid exposing the fetus
to harmful levels of radiation. This directive was binding for all
European Union member states and became effective in May 2000.
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• Improved awareness of potential health effects related to flying: Air
travel may exacerbate some medical conditions. Of particular concern is
a condition known as Deep Vein Thrombosis (DVT), or travelers’
thrombosis, in which blood clots can develop in the deep veins of the
legs from extended periods of inactivity. In a small percentage of cases,
the clots can break free and travel to the lungs, with potentially fatal
results. Although steps can be taken to avoid or mitigate some travelrelated health effects, no formal awareness campaigns have been
initiated by FAA to help ensure that this information reaches physicians
and the traveling public. The Aerospace Medical Association’s Web site
http://www.asma.org/publication.html includes guidance for physicians
to use in advising passengers with preexisting medical conditions on the
potential risks of flying, as well as information for passengers with such
conditions to use in assessing their own potential risks.
See appendix VII for additional information on health-related advances.
Advancements Vary in Their
Readiness for Deployment
The advancements being pursued to improve the safety and health of cabin
occupants vary in their readiness for deployment. For example, of the 28
advancements we reviewed, 14 are mature and currently available. Two of
these, preparation for in-flight medical emergencies and the use of new
insulation, were addressed through regulations. These regulations require
airlines to install additional emergency medical equipment (automatic
external defibrillators and enhanced emergency medical kits) by 2004,
replace flammable insulation covering (metalized Mylar®) on specific
aircraft by 2005, and manufacture new large commercial airliners that use a
new type of insulation meeting more stringent flammability test standards
after September 2, 2005. Another advancement is currently in the rulemaking process—retrofitting the existing fleet with stronger 16g seats. The
remaining 11 advancements are available, but are not required by FAA. For
example, some airlines have elected to use inflatable lap seat belts and exit
doors over the wings that swing out instead of requiring manual removal,
and others are using photo-luminescent floor lighting in lieu of or in
combination with traditional electrical lighting. Some of these
advancements are commercially available to the flying public, including
smoke hoods and child safety seats certified for use on commercial
airliners. The remaining 14 advancements are in various stages of research,
engineering, and development in the United States, Canada, or Europe.
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Several Factors Have
Slowed the
Implementation of
Cabin Occupant Safety
and Health
Advancements
Several factors have slowed the implementation of airliner cabin occupant
safety and health advancements in the United States. When advancements
are available for commercial use but not yet implemented or installed, their
use may be slowed by the time it takes (1) for FAA to complete the rulemaking process,10 which may be required for an advancement to be
approved for use but may take many years; (2) for U.S. and foreign aviation
authorities to resolve differences between their respective cabin occupant
safety and health requirements; and (3) for the airlines to adopt or install
advancements after FAA has approved their use, including the time
required to schedule an advancement’s installation to coincide with major
maintenance cycles and thereby minimize the costs associated with taking
an airplane out of service. When advancements are not ready for
commercial use because they need further research to develop their
technologies or reduce their costs, their implementation may be slowed by
FAA’s multistep process for identifying advancements and allocating its
limited resources to research on potential advancements. FAA’s multistep
process is hampered by a lack of autopsy and survivor information from
past accidents and by not having cost and effectiveness data as part of the
decision process. As a result, FAA may not be identifying and funding the
most critical or cost-effective research projects.
FAA’s Rule-making Process
to Require Advancements
Can Be Lengthy
Once an advancement has been developed, FAA may require its use, but
significant time may be required before the rule-making process is
complete. One factor that contributes to the length of this process is a
requirement for cost-benefit analyses to be completed. Time is particularly
important when safety is at stake or when the pace of technological
development exceeds the pace of rule-making. As a result, some rules may
need to be developed quickly to address safety issues or to guide the use of
new technologies. However, rules must also be carefully considered before
being finalized because they can have a significant impact on individuals,
industries, the economy, and the environment. External pressures—such as
political pressure generated by highly publicized accidents,
recommendations by NTSB, and congressional mandates—as well as
internal pressures, such as changes in management’s emphasis, continue to
add to and shift the agency’s priorities.
10
ATA noted that, for those technologies that are ready, FAA must develop design and
certification standards before undertaking the rule-making process to require their
implementation.
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The rule-making process can be long and complicated and has delayed the
implementation of some technological and operational safety
improvements, as we reported in July 2001.11 In that report, we reviewed 76
significant rules in FAA’s workload for fiscal years 1995 through 2000—10
of the 76 were directly related to improving the safety and health of cabin
occupants.12 Table 3 details the status or disposition of these 10 rules. The
shortest rule-making action took 1 year, 11 months (for child restraint
systems), and the longest took 10 years, 1 month (for the type and number
of emergency exits). However, one proposed rule was still pending after 15
years, while three others were terminated or withdrawn after 9 years or
more. Of the 76 significant rules we reviewed, FAA completed the rulemaking process for 29 of them between fiscal year 1995 and fiscal year
2000, in a median time of about 2 ½ years to proceed from formal initiation
of the rule-making process through publication of the final rule; however,
FAA took 10 years or more to move from formal initiation of the rulemaking process through publication of the final rule for 6 of these 29 rules.
Table 3: Status of 10 Significant FAA Rules Pertaining to Airliner Cabin Occupants’ Safety and Health, Fiscal Year 1995 through
September of Fiscal Year 2003
Initiation datea
Rule title
Flight attendant requirements
Time elapsed
Status/disposition
2/04/86
9 years, 8 months
Terminated/withdrawn 6/06/96
10/15/86
10 years, 1 month
Final rule published on
11/08/96
Airworthiness standards; occupant protection
standards for commuter category airplanes
5/29/87
11 years, 1 month
Terminated/withdrawn
6/30/98
Retrofit of improved seats in air carrier transport
category airplanes
1/26/88
15 years, 6 months
Child restraint systems
5/30/90
5 years, 9 months
Type and number of passenger emergency exits
required in transport category airplanes
Pending
Terminated/withdrawn
2/13/96
11
U.S. General Accounting Office, Aviation Rule-making: Further Reform Is Needed to
Address Long-standing Problems, GAO-01-821 (Washington, D.C.: July 9, 2001).
12
Under Executive Order 12866, federal agencies and the Office of Management and Budget
(OMB) categorize proposed and final rules in terms of their potential impact on the
economy and the industry affected. The Order defines a regulatory action as “significant” if
it, among other things, has an annual impact on the economy of $100 million or more and
adversely affects the economy in a material way. To measure the overall impact of the 1998rule-making reforms, through discussions with FAA officials, we created a database of 76
significant rules. These rules constituted the majority (about 83 percent) of FAA’s significant
rule workload from fiscal year 1995 through fiscal year 2000.
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(Continued From Previous Page)
Rule title
Revised access to Type III exits
Initiation datea
Time elapsed
10/30/92
9 years, 5 months
Withdrawn
5/03/02
Status/disposition
Child restraint systems
7/18/94
1 year 11 months
Final rule published on 6/04/96
Child restraint systems
4/07/97
6 years, 3 months
Pending
Emergency medical equipment
10/5/98
2 years, 8 months
Final rule published on
6/12/01
12/04/98
4 years, 7 months
Final rule published on July 31,
2003
Improved flammability standards for thermal
acoustic insulation materials in transport category
aircraft
Source: GAO analysis of FAA data.
Note: In commenting on a draft of this report, FAA noted that examining the years elapsed from the
initiation date of the rule to disposition can be unfair to some actions and that many of the delays were
not the fault of FAA.
a
Initiation dates were identified in FAA’s rule-making information system as GAO reported in July 2001.
This was the only source for data on the agency’s internal milestones, including “initiation date.”
Differences in U.S. and
Foreign Requirements Can
Hamper Adoption of
Advancements
FAA and its international counterparts, such as the European Joint Aviation
Authorities (JAA), impose a number of requirements to improve safety. At
times, these requirements differ, and efforts are needed to reach agreement
on procedures and equipment across country borders. In the absence of
such agreements, the airlines generally must adopt measures to implement
whichever requirement is more stringent. In 1992, FAA and JAA began
harmonizing their requirements for (1) the design, manufacture, operation,
and maintenance of civil aircraft and related product parts; (2) noise and
emissions from aircraft; and (3) flight crew licensing. Harmonizing the U.S.
Federal Aviation Regulations with the European Joint Aviation Regulations
is viewed by FAA as its most comprehensive long-term rule-making effort
and is considered critical to ensuring common safety standards and
minimizing the economic burden on the aviation industry that can result
from redundant inspection, evaluation, and testing requirements.
According to both FAA and JAA, the process they have used to date to
harmonize their requirements for commercial aircraft has not effectively
prioritized their joint recommendations for harmonizing U.S. and European
aviation requirements, and led to many recommendations going
unpublished for years. This includes a backlog of over 130 new rule-making
efforts. The slowness of this process led the United States and Europe to
develop a new rule-making process to prioritize safety initiatives, focus the
aviation industry’s and their own limited resources, and establish
limitations on rule-making capabilities. Accordingly, in March 2003, FAA
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and JAA developed a draft joint “priority” rule-making list; collected and
considered industry input; and coordinated with FAA’s, JAA’s, and
Transport Canada Civil Aviation’s management. This effort has resulted in a
rule-making list of 26 priority projects. In June 2003, at the 20th Annual
JAA/FAA International Conference, FAA, JAA, and Transport Canada Civil
Aviation discussed the need to, among other things, support the joint
priority rule-making list and to establish a cycle for updating it—to keep it
current and to provide for “pop-up,” or unexpected, rule-making needs.
FAA and JAA discussed the need to prioritize rule-making efforts to
efficiently achieve aviation safety goals; that they would work from a
limited agreed-upon list for future rule-making activities; and that FAA and
the European Aviation Safety Agency, which is gradually replacing JAA,
should continue with this approach.
In the area of cabin occupant safety and heath, some requirements have
been harmonized, while others have not. For example, in 1996, JAA
changed its rule on floor lighting to allow reflective, glow-in-the-dark
material to be used rather than mandating the electrically powered lighting
that FAA required. The agency subsequently permitted the use of this
material for floor lighting. In addition, FAA finalized a rule in July 2003 to
require a new type of insulation designed to delay fire burning though the
fuselage into the cabin during an accident. JAA favors a performance-based
standard that would specify a minimum delay in burn-through time, but
allow the use of different technologies to achieve the standard. FAA
officials said that the agency would consider other technologies besides
insulation to achieve burn-through protection but that it would be the
responsibility of the applicant to demonstrate that the technology provided
performance equivalent to that stipulated in the insulation rule. JAA
officials told us that these are examples of the types of issues that must be
resolved when they work to harmonize their requirements with FAA’s.
These officials added that this process is typically very time consuming and
has allowed for harmonizing about five rules per year.
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Significant Time May Be
Needed to Implement
Advancements Once They
Are Required, but Some May
Enhance Airlines’
Competitiveness
After an advancement has been developed, shown to be beneficial,
certified, and required by FAA, the airlines or manufacturers need time to
implement or install the advancement.13 FAA generally gives the airlines or
manufacturers a window of time to comply with its rules. For example,
FAA gave air carriers 5 years to replace metalized Mylar® insulation on
specific aircraft with a less flammable insulation type, and FAA’s proposed
rule-making on 16g seats would give the airlines 14 years to install these
seats in all existing commercial airliners. ATA officials told us that this
would require replacement of 496,000 seats.
The airline industry’s recent financial hardships may also delay the
adoption of advancements. Recently, two major U.S. carriers filed for
bankruptcy,14 and events such as the war in Iraq have reduced passenger
demand and airline revenues below levels already diminished by the events
of September 11, 2001, and the economic downturn. Current U.S. demand
for air travel remains below fiscal year 2000 levels. As a result, airlines may
ask for exemptions from some requirements or extensions of time to install
advancements.
While implementing new safety and health advancements can be costly for
the airlines, making these changes could improve the public’s confidence in
the overall safety of air travel. In addition, some aviation experts in Europe
told us that health-related cabin improvements, particularly improvements
in air quality, are of high interest to Europeans and would likely be used in
the near future by some European air carriers to set themselves apart from
their competitors.
13
According to ATA, even if a technology is available in the marketplace, it may not be
adopted by the airlines until it has been certified by FAA--ensuring that “improvements” do
not inadvertently compromise overall safety of the aircraft.
14
One of these U.S. carriers is no longer in bankruptcy.
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FAA’s Multistep Process for
Allocating Limited
Resources to Research
Projects Is Hampered by
Lack of Autopsy and
Survivor Information and
Cost and Effectiveness Data
For fiscal year 2003, FAA and NASA allocated about $16.2 million to cabin
occupant safety and health research. FAA’s share of this research
represented $13.1 million, or about 9 percent of the agency’s Research,
Engineering, and Development budget of $148 million for fiscal year 2003.
Given the level of funding allocated to this research effort, it is important to
ensure that the best research projects are selected. However, FAA’s
processes for setting research priorities and selecting projects for further
research are hampered by data limitations. In particular, FAA lacks certain
autopsy and survivor information from aircraft crashes that could help it
identify and target research to the most important causes of death and
injury in an airliner crash. In addition, for the proposed research projects,
the agency does not (1) develop comparable cost data for potential
advancements or (2) assess their potential effectiveness in minimizing
injuries or saving lives. Such cost and effectiveness data would provide a
valuable supplement to FAA’s current process for setting research priorities
and selecting projects for funding.
Federal Research on Aircraft
Cabin Occupant Safety and
Health Issues
Both FAA and NASA conduct research on aircraft cabin occupant safety
and health issues. The Civil Aeromedical Institute (CAMI) and the Hughes
Technical Center are FAA’s primary facilities for conducting research in this
area. In addition, two facilities at NASA, the Langley and Glenn research
centers, have also conducted research in this area. As figure 3 shows,
federal funding for this research since fiscal year 2000, reached a high in
fiscal year 2002, at about $17 million, and fell to about $16.2 million in fiscal
year 2003. The administration’s proposal for fiscal year 2004 calls for a
further reduction to $15.9 million. This funding covers the expenses of
researchers at these facilities and of the contracts they may have with
others to conduct research. In addition, NASA recently decided to end its
crash research at Langley and to close a drop test facility that it operates in
Hampton, Virginia.
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Figure 3: Funding for Federal Research on Cabin Occupant Safety and Health
Issues, by Facility, Fiscal Years 2000-2005
Note: FAA Hughes Technical Center data includes work in fire-safe fuels, fuel-tank inerting, arc fault
circuit breakers, and airport rescue and fire-fighting operations.
In fiscal year 2003, FAA and NASA both supported research projects,
including aircraft impact, fire, evacuation, and health. As figure 4 shows,
most of the funding for cabin occupant safety and health research has gone
to fire-related projects.
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Figure 4: Allocation of Federal Funding for Aircraft Cabin Occupant Safety and
Health Research, Fiscal Year 2003
Note: Sum of bars exceeds $16.2 million due to rounding. FAA Technical Center data includes work in
fire-safe fuels, fuel-tank inerting, arc fault circuit breakers, and airport rescue and fire-fighting
operations
FAA Research Selection Process
Hampered by Lack of Autopsy
and Survivor Information and
Cost and Effectiveness Analyses
To establish research priorities and select projects to fund, FAA uses a
multistep process. First, within each budget cycle, a number of Technical
Community Representative Group subcommittees from within FAA
generate research ideas. Various subcommittees have responsibility for
identifying potential safety and health projects, including subcommittees
on crash dynamics, fire safety, structural integrity, passenger evacuation,
aeromedical, and fuel safety. Each subcommittee proposes research
projects to review committees, which prioritize the projects. The projects
are considered and weighted according to the extent to which they address
(1) accident prevention, (2) accident survival, (3) external requests for
research, (4) internal requests for research, and (5) technology research
needs. In addition, the cost of the proposed research is considered before
arriving at a final list of projects. The prioritized list is then considered by
the Program Planning Team, which reviews the projects from a policy
perspective.
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Although the primary causes of death and injury in commercial airliner
crashes are known to be impact, fire, and impediments to evacuation, FAA
does not have as detailed an understanding as it would like of the critical
factors affecting survival in a crash. According to FAA officials, obtaining a
more detailed understanding of these factors would assist them in setting
research priorities and in evaluating the relative importance of competing
research proposals. To obtain a more detailed understanding of the critical
factors affecting survival, FAA believes that it needs additional information
from passenger autopsies and from passengers who survived. With this
information, FAA could then regulate safety more effectively, airplane and
equipment designers could build safer aircraft, including cabin interiors,
and more passengers could survive future accidents as equipment became
safer.
While FAA has independent authority to investigate commercial airliner
crashes, NTSB generally controls access to the accident investigation site
in pursuit of its primary mission of determining the cause of the crash.
When NTSB concludes its investigation, it returns the airplane to its owner
and keeps the records of the investigation, including the autopsy reports
and the information from survivors that NTSB obtains from medical
authorities and through interviews or questionnaires. NTSB makes
summary information on the crashes publicly available on its Web site, but
according to the FAA researchers, this information is not detailed enough
for their needs. For example, the researchers would like to develop a
complete autopsy database that would allow them to look for common
trends in accidents, among other things. In addition, the researchers would
like to know where survivors sat on the airplane, what routes they took to
exit, what problems they encountered, and what injuries they sustained.
This information would help the researchers analyze factors that might
have an impact on survival. According to the NTSB’s Chief of the Survival
Factors Division in the Office of Aviation Safety, NTSB provides
information on the causes of death and a description of injuries in the
information they make publicly available. In addition, although medical
records and autopsy reports are not made public, interviews with and
questionnaires from survivors are available from the public docket.
NTSB’s Medical Officer was unaware of any formal requests from the FAA
for the NTSB to provide them with copies of this type of information,
although the FAA had previously been invited to review such information at
NTSB headquarters. He added that the Board would likely consider a
formal request from FAA for copies of autopsy reports and certain survivor
records, but that it was also likely that the FAA would have to assure NTSB
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GAO-04-33 Airliner Cabin Occupant Safety and Health
that the information would be appropriately safeguarded. According to
FAA officials, close cooperation between the NTSB and the FAA is needed
for continued progress in aviation safety.
Besides lacking detailed information on the causes of death and injury, FAA
does not develop data on the cost to implement advancements that are
comparable for each, nor does it assess the potential effectiveness of each
advancement in reducing injuries and saving lives. Specifically, FAA does
not conduct cost-benefit analyses as part of its multistep process for setting
research priorities. Making cost estimates of competing advancements
would allow direct comparisons across alternatives, which, when
combined with comparable estimates of effectiveness, would provide
valuable supplemental information to decision makers when setting
research priorities. FAA considers its current process to be appropriate and
sufficient. In commenting on a draft of this report, FAA noted that it is very
difficult to develop realistic cost data for advancements during the earliest
stages of research. The agency cautioned that if too much emphasis is
placed on cost/benefit analyses, potentially valuable research may not be
undertaken. Recognizing that it is less difficult to develop cost and
effectiveness information as research progresses, we are recommending
that FAA develop and use cost and effectiveness analyses to supplement its
current process. At later stages in the development process, we found that
this information can be developed fairly easily through cost and
effectiveness analyses using currently available data. For example, we
performed an analysis of the cost to implement inflatable lap seat belts
using a cost analysis methodology we developed (see app. VIII). This
analysis allowed us to estimate how much this advancement would cost
per airplane and per passenger trip. Such cost analyses could be combined
with similar analyses of effectiveness to identify the most cost-effective
projects, based on their potential to minimize injuries and reduce fatalities.
Potential sources of effectiveness data include FAA, academia, industry,
and other aviation authorities.
Conclusions Although FAA and the aviation community are pursuing a number of
advancements to enhance commercial airliners’ cabin occupant safety and
health, several factors have slowed their implementation. For example, for
advancements that are currently available but are not yet implemented or
installed, progress is slowed by the length of time it takes for FAA to
complete its rule-making process, for the U.S and foreign countries to agree
on the same requirements, and for the airlines to actually install the
advancements after FAA has required them. In addition, FAA’s multistep
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process for identifying potential cabin occupant safety and health research
projects and allocating its limited research funding is hampered by the lack
of autopsy and survivor information from airliner crashes and by the lack
of cost and effectiveness analysis. Given the level of funding allocated to
cabin occupant safety and health research, it is important for FAA to
ensure that this funding is targeting the advancements that address the
most critical needs and show the most promise for improving the safety
and health of cabin occupants. However, because FAA lacks detailed
autopsy and survivor information, it is hampered in its ability to identify the
principal causes of death and survival in commercial airliner crashes.
Without an agreement with the National Transportation Safety Board
(NTSB) to receive detailed autopsy and survivor information, FAA lacks
information that could be helpful in understanding the factors that
contribute to surviving a crash. Furthermore, because FAA does not
develop comparable estimates of cost and effectiveness of competing
research projects, it cannot ensure that it is funding those technologies
with the most promise of saving lives and reducing injuries. Such cost and
effectiveness data would provide a valuable supplement to FAA’s current
process for setting research priorities and selecting projects for funding. To
facilitate FAA’s development of comparable cost data across
advancements, we developed a cost analysis methodology that could be
combined with a similar analysis of effectiveness to identify the most costeffective projects. Using comparable cost and effectiveness data across the
range of advancements would position the agency to choose more
effectively between competing advancements, taking into account
estimates of the number of injuries and fatalities that each advancement
might prevent for the dollars invested. In turn, FAA would have more
assurance that the level of funding allocated to this effort maximizes the
safety and health of the traveling public and the cabin crew members who
serve them.
Recommendations for
Executive Action
To provide FAA decision makers with additional data for use in setting
priorities for research on cabin occupant safety and health and in selecting
competing research projects for funding, we recommend that the Secretary
of Transportation direct the FAA Administrator to
• initiate discussions with the National Transportation Safety Board in an
effort to obtain the autopsy and survivor information needed to more
fully understand the factors affecting survival in a commercial airliner
crash and
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GAO-04-33 Airliner Cabin Occupant Safety and Health
• supplement its current process by developing and using comparable
estimates of cost and effectiveness for each cabin occupant safety and
health advancement under consideration for research funding.
Agency Comments and Our Evaluation
We provided copies of a draft of this report to the Department of
Transportation for its review and comment. FAA generally agreed with the
report’s contents and its recommendations. The agency provided us with
oral comments, primarily technical clarifications, which we have
incorporated as appropriate.
As agreed with your office, unless you publicly announce its contents earlier, we plan no further distribution of this report until 10 days after the date of this letter. At that time, we will send copies to the appropriate congressional committees; the Secretary of Transportation; the Administrator, FAA; and the Chairman, NTSB. We will also make copies available to others upon request. In addition, this report is also available at no charge on GAO’s Web site at http://www.gao.gov.
Contacts and staff acknowledgements for this report are included in
appendix IX. If you or your staff have any questions, please contact me or
Glen Trochelman at (202) 512-2834 Sincerely yours,
Gerald L. Dillingham
Director, Physical Infrastructure Issues
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Appendix I
Objectives, Scope, and Methodology
As requested by the Ranking Democratic Member, House Committee on
Transportation and Infrastructure, we addressed the following questions:
(1) What regulatory actions has the Federal Aviation Administration (FAA)
taken, and what key advancements are available or being developed by
FAA and others to address safety and health issues faced by passengers and
flight attendants in large commercial airliner cabins? (2) What factors, if
any, slow the implementation of advancements in cabin occupant safety
and health? In addition, as requested, we identified some factors affecting
efforts by Canada and Europe to improve cabin occupant safety and health.
The scope of our report includes the cabins of large commercial aircraft
(those that carry 30 or more passengers) operated by U.S. domestic
commercial airlines and addresses the safety and health of passengers and
flight attendants from the time they board the airliner until they disembark
under normal operational conditions or emergency situations. This report
identifies cabin occupant safety and health advancements (technological or
operational improvements) that could be implemented, primarily through
FAA’s rule-making process. Such improvements include technological
changes designed to increase the overall safety of commercial aviation as
well as changes to enhance operational safety. The report does not include
information on the flight decks of large commercial airliners or safety and
health issues affecting flight deck crews (pilots and flight engineers),
because they face some issues not faced by cabin occupants. It also does
not address general aviation and corporate aircraft or aviation security
issues, such as hijackings, sabotage, or terrorist activities.
To identify regulatory actions that FAA has taken to address safety and
health issues faced by passengers and flight attendants in large commercial
airliner cabins, we interviewed and collected documentation from U.S.
federal agency officials on major safety and health efforts completed by
FAA. The information we obtained included key dates and efforts related to
cabin occupant safety and health, such as rule-makings, airworthiness
directives, and Advisory Circulars.
To identify key advancements that are available or are being developed by
FAA and others to address safety and health issues faced by passengers and
flight attendants in large commercial airliner cabins, we consulted experts
(1) to help ensure that we had included the advancements holding the most
promise for improving safety and health; and (2) to help us structure an
evaluation of selected advancements (i.e., confirm that we had included the
critical benefits and drawbacks of the potential advancements) and
develop a descriptive analysis for them, where appropriate, including their
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Appendix I
Objectives, Scope, and Methodology
benefits, costs, technology readiness levels, and regulatory status. In
addition, we interviewed and obtained documentation from federal agency
officials and other aviation safety experts at the Federal Aviation
Administration (including its headquarters in Washington, D.C.; Transport
Airplane Directorate in Renton, Washington; William J. Hughes Technical
Center in Atlantic City, New Jersey; and Mike Monroney Aeronautical
Center/Civil Aerospace Medical Institute in Oklahoma City, Oklahoma);
National Transportation Safety Board; National Aeronautics and Space
Administration (NASA); Air Transport Association; Regional Airline
Association; International Air Transport Association; Aerospace Industries
Association; Aerospace Medical Association; Flight Safety Foundation,
Association of Flight Attendants; Boeing Commercial Airplane Group;
Airbus; Cranfield University, United Kingdom; University of Greenwich,
United Kingdom; National Aerospace Laboratory, Netherlands; Joint
Aviation Authorities, Netherlands; Civil Aviation, Netherlands; Civil
Aviation Authority, United Kingdom; RGW Cherry and Associates; Air
Accidents Investigations Branch, United Kingdom; Syndicat National du
Personnel Navigant Commercial (French cabin crew union) and ITF Cabin
Crew Committee, France; BEA (comparable to the U.S. NTSB), France; and
the Direction Générale de l’Aviation Civile (DGAC), FAA’s French
counterpart.
To describe the status of key advancements that are available or under
development, we used NASA’s technology readiness levels (TRL). These
levels form a system for ranking the maturity of particular technologies and
are as follows:
• TRL 1: Basic principles observed and reported
• TRL 2: Technology concept and/or application formulated
• TRL 3: Analytical and experimental critical function and/or
characteristic proof-of-concept developed
• TRL 4: Component validation in laboratory environment
• TRL 5: Component and/or validation in relevant environment
• TRL 6: System or subsystem model or prototype demonstrated in a
relevant environment
• TRL 7: System prototype demonstrated in a space environment
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Appendix I
Objectives, Scope, and Methodology
• TRL 8: Actual system completed and “flight qualified” through test and
demonstration
• TRL 9: Actual system “flight proven” through successful mission
operations
To determine what factors, if any, slow the implementation of
advancements in cabin occupant safety and health, we reviewed the
relevant literature and interviewed and analyzed documentation from the
U.S. federal officials cited above for the 18 key regulatory actions FAA has
taken since 1984 to improve the safety and health of cabin occupants. We
used this same approach to assess the regulatory status of the 28
advancements we reviewed that are either currently available, but not yet
implemented or installed, or require further research to demonstrate their
effectiveness or lower their costs. In identifying 28 advancements, GAO is
not suggesting that these are the only advancements being pursued; rather,
these advancements have been recognized by aviation safety experts we
contacted as offering promise for improving the safety and health of cabin
occupants. To determine how long it generally takes for FAA to issue new
rules, in addition to speaking with FAA officials, we relied on past GAO
work and updated it, as necessary. In order to examine the effect of FAA
and European efforts to harmonize their aviation safety requirements, we
interviewed and analyzed documentation from aviation safety officials and
other experts in the United States, Canada, and Europe. Furthermore, to
examine the factors affecting airlines’ ability to implement or install
advancements after FAA requires them, we interviewed and analyzed
documentation from aircraft manufacturers, ATA, and FAA officials.
In addition, to determine what factors slow implementation we examined
FAA’s processes for selecting research projects to improve cabin occupant
safety and health. In examining whether FAA has sufficient data upon
which to base its research priorities, we interviewed FAA and National
Transportation Safety Board (NTSB) officials about autopsy and survivor
information from commercial airliner accidents. We also examined the use
of cost and effectiveness data in FAA’s research selection process for cabin
occupant safety and health projects. To facilitate FAA’s development of
such cost estimates, we developed a cost analysis methodology to illustrate
how the agency could do this. Specifically, we developed a cost analysis for
inflatable lap belts to show how data on key cost variables could be
obtained from a variety of sources. We selected lap belts because they were
being used in limited situations and appeared to offer some measure of
improved safety. Information on installation price, annual maintenance and
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Appendix I
Objectives, Scope, and Methodology
refurbishment costs, and added weight of these belts was obtained from
belt manufacturers. We obtained information from FAA and the
Department of Transportation’s (DOT) Bureau of Transportation Statistics
on a number of cost variables, including historical jet fuel prices, the
impact on jet fuel consumption of carrying additional weight, the average
number of hours flown per year, the average number of seats per airplane,
the number of airplanes in the U.S. fleet, and the number of passenger
tickets issued per year. To account for variation in the values of these cost
variables, we performed a Monte Carlo simulation.1 In this simulation,
values were randomly drawn 10,000 times from probability distributions
characterizing possible values for the number of seat belts per airplane,
seat installation price, jet fuel price, number of passenger tickets, number
of airplanes, and hours flown. This simulation resulted in forecasts of the
life-cycle cost per airplane, the annualized cost per airplane, and the cost
per ticket. There is uncertainty in estimating the number of lives potentially
saved and their value because accidents occur infrequently and
unpredictably. Such estimates could be higher or lower, depending on the
number and severity of accidents during a given analysis period and the
value placed on a human life.
To identify factors affecting efforts by Canada and Europe to improve cabin
occupant safety and health we interviewed and collected documentation
from aviation safety experts in the United States, Canada, and Europe.
We provided segments of a draft of this report to selected external experts
to help ensure its accuracy and completeness. These included the Air
Transport Association, National Transportation Safety Board, Boeing,
Airbus, and aviation authorities in the United Kingdom, France, Canada
and the European Union. We incorporated their comments, as appropriate.
The European Union did not provide comments.
We conducted our review from January 2002 through September 2003 in
accordance with generally accepted government auditing standards.
1
A Monte Carlo simulation is a widely used computational method for generating probability
distributions of variables that depend on other variables or parameters represented as
probability distributions.
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Appendix II
Canada and Europe Cabin Occupant Safety
and Health Responsibilities
The United States, Canada, and members of the European Community are
parties to the International Civil Aviation Organization (ICAO), established
under the Chicago Convention of 1944, which sets minimum standards and
recommended practices for civil aviation. In turn, individual nations
implement aviation standards, including those for aviation safety. While
ICAO’s standards and practices are intended to keep aircraft, crews, and
passengers safe, some also address environmental conditions in aircraft
cabins that could affect the health of passengers and crews. For example,
ICAO has standards for preventing the spread of disease and for spraying
aircraft cabins with pesticides to remove disease-carrying insects.
Canada
In Canada, FAA’s counterpart for aviation regulations and oversight is
Transport Canada Civil Aviation, which sets standards and regulations for
the safe manufacture, operation, and maintenance of aircraft in Canada. In
addition, Transport Canada Civil Aviation administers, enforces, and
promotes the Aviation Occupational Health and Safety Program to help
ensure the safety and health of crewmembers on board aircraft.1 The
department also sets the training and licensing standards for aviation
professionals in Canada, including air traffic controllers, pilots, and aircraft
maintenance engineers. Transport Canada Civil Aviation has more than 800
inspectors working with Canadian airline operators, aircraft
manufacturers, airport operators, and air navigation service providers to
maintain the safety of Canada’s aviation system. These inspectors monitor,
inspect, and audit Canadian aviation companies to verify their compliance
with Transport Canada’s aviation regulations and standards for pilot
licensing, aircraft certification, and aircraft operation.
To assess and recommend potential changes to Canada’s aviation
regulations and standards, the Canadian Aviation Regulation Advisory
Council was established. This Council is a joint initiative between
government and the aviation community. The Council supports regulatory
meetings and technical working groups, which members of the aviation
community can attend. A number of nongovernmental organizations—
including airline operators, aviation labor organizations, manufacturers,
industry associations, and groups representing the public—are members.
1
The Headquarters Division of Transport Canada provides guidance and assistance to
Regional Civil Aviation Safety Inspectors – Occupational Health and Safety who conduct
inspections, investigations, and promotional visits to ensure that airline operators are
committed to the safety and health of their employees.
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GAO-04-33 Airliner Cabin Occupant Safety and Health
Appendix II
Canada and Europe Cabin Occupant Safety and Health Responsibilities
The Transportation Safety Board (TSB) of Canada is similar to NTSB in the
United States. TSB is a federal agency that operates independently of
Transport Canada Civil Aviation. Its mandate is to advance safety in the
areas of marine, pipeline, rail, and aviation transportation by
• conducting independent investigations, including public inquiries when
necessary, into selected transportation occurrences in order to make
findings as to their causes and contributing factors;
• identifying safety deficiencies, as evidenced by transportation
occurrences;
• making recommendations designed to reduce or eliminate any such
deficiencies; and
• reporting publicly on their investigations and findings.
Under its mandate to conduct investigations, TSB conducts safety-issuerelated investigations and studies. It also maintains a mandatory incidentreporting system for all modes of transportation. TSB and Transport
Canada Civil Aviation use the statistics derived from this information to
track potential safety concerns in Canada’s transportation system.
TSB investigates aircraft accidents that occur in Canada or involve aircraft
built there. Like NTSB, the Transportation Safety Board can recommend air
safety improvements to Transport Canada Civil Aviation.
Europe Europe supplements the ICAO framework with the European Civil Aviation
Conference, an informal forum through which 38 European countries
formulate policy on civil aviation issues, including safety, but do not
explicitly address passenger health issues. In addition, the European Union
issues legislation concerning aviation safety, certification, and licensing
requirements but has not adopted legislation specifically related to
passenger health. One European directive requires that all member states
assess and limit crewmembers’ exposure to radiation from their flight
duties and provide them with information on the effects of such radiation
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Appendix II
Canada and Europe Cabin Occupant Safety and Health Responsibilities
exposure. The European Commission2 is also providing flight
crewmembers and other mobile workers with free health assessments
prior to employment, with follow-up health assessments at regular
intervals.
Another European supplement to the ICAO framework is the Joint Aviation
Authorities (JAA), which represents the civil aviation regulatory authorities
of a number of European states3 that have agreed to cooperate in
developing and implementing common safety regulatory standards and
procedures. JAA uses staff of these authorities to carry out its
responsibilities for making, standardizing, and harmonizing aviation rules,
including those for aviation safety, and for consolidating common
standards among member counties. In addition, JAA is to cooperate with
other regional organizations or national European state authorities to reach
at least JAA’s safety level and to foster the worldwide implementation of
harmonized safety standards and requirements through the conclusion of
international arrangements.
Membership in JAA is open to members of the European Civil Aviation
Conference, which currently consists of 41 member countries. Currently, 37
countries are members or candidate members of JAA. JAA is funded by
national contributions; income from the sale of publications and training;
and income from other sources, such as user charges and European Union
grants. National contributions are based on indexes related to the size of
each country’s aviation industry. The “largest” countries (France, Germany,
and the United Kingdom) each pay around 16 percent and the smallest
around 0.6 percent of the total contribution income. For 2003, JAA’s total
budget was about 6.6 million euros.
In early 1998, JAA launched the Safety Strategy Initiative to develop a
focused safety agenda to support the “continuous improvement of its
effective safety system” and further reduce the annual number of accidents
and fatalities regardless of the growth of air traffic. Two approaches are
being used to develop the agenda:
2
The European Union, previously known as the European Community, is an institutional
framework for the construction of a united Europe. The European Commission is a
governing body that proposes policies and legislation.
3
JAA currently has 26 full members and 11 candidate members.
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Appendix II
Canada and Europe Cabin Occupant Safety and Health Responsibilities
• The “historic approach” is based on analyses of past accidents and has
led to the identification of seven initial focus areas—controlled flight
into terrain, approach and landing, loss of control, design related,
weather, occupant safety and survivability, and runway safety.
• The “predictive approach” or “future hazards approach” is based on an
identification of changes in the aviation system.
JAA is cooperating in this effort with FAA and other regulatory bodies to
develop a worldwide safety agenda and avoid duplication of effort. FAA has
taken the lead in the historic approach, and JAA has taken the lead in the
future hazards approach.
JAA officials told us that they use a consensus-based process to develop
rules for aviation safety, including cabin occupant safety and health-related
issues. Reaching consensus among member states is time consuming, but
the officials said the time invested was worthwhile. Besides making
aviation-related decisions, JAA identifies and resolves differences in word
meanings and subtleties across languages—an effort that is critical to
reaching consensus. JAA does not have regulatory rule-making authority.
Once the member states are in agreement, each member state’s legislative
authority must adopt the new requirements. Harmonizing new
requirements with U.S. and other international aviation authorities further
adds to the time required to implement new requirements.
According to JAA officials, they use expert judgment to identify and
prioritize research and development efforts for aviation safety, including
airliner cabin occupant safety and health issues, but JAA plans to move
toward a more data-driven approach.4 While JAA has no funding of its own
for research and development, it recommends research priorities to its
member states. However, JAA officials told us that member states’ research
and development efforts are often driven by recent airliner accidents in the
member states, rather than by JAA’s priorities. The planned shift from
expert judgment to a more data-driven approach will require more
coordination of aviation research and development across Europe. For
example, in January 2001, a stakeholder group formed by the European
Commissioner for Research issued a planning document entitled European
4
According to officials from the United Kingdom’s Civil Aviation Authority, a JAA member, a
limited benefit analysis has been developed to provide guidance, but this document has not
yet been published.
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Appendix II
Canada and Europe Cabin Occupant Safety and Health Responsibilities
Aeronautics: A Vision for 2020, which, among other things, characterized
European aeronautics as a cross-border industry, whose research strategy
is shaped within national borders, leading to fragmentation rather than
coherence. The document called for better decision-making and more
efficient and effective research by the European Union, its member states,
and aeronautics stakeholders. JAA officials concurred with this
characterization of European aviation research and development.
Changes lie ahead for JAA and aviation safety in Europe. The European
Union recently created a European Aviation Safety Agency, which will
gradually assume responsibility for rule-making, certification, and
standardization of the application of rules by the national aviation
authorities. This organization will eventually absorb all of JAA’s functions
and activities. The full transition from JAA to the safety agency will take
several years--per the regulation,5 the European Aviation Safety Agency
must begin operations by September 28, 2003, and transition to full
operations by March 2007.
5
On July 15, 2002, the European Parliament and the Council of the European Union (E.U.)
adopted Regulation (EC) No 1592/2002 establishing common rules for the E.U. in the field of
civil aviation and establishing a new European Aviation Safety Agency.
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Appendix III
Summary of Key Actions FAA Has Taken to
Improve Airliner Cabin Safety and Health
Since 1984
Key improvement areas
Action taken
Purpose
Status
Stronger (16g) passenger
seats
FAA required that seats for newly developed
aircraft be subjected to more rigorous testing
than was previously required. The tests subject
seats to the forward, downward, and other
directional movements that can occur in an
accident. Likely injuries under various
conditions are estimated by using instrumented
crash test dummies.
To improve the
crashworthiness of
airplane seats and
their ability to prevent
or reduce the severity
of head, back, and
femur injuries.
This rule was published on May
17, 1988, and became effective
June 16, 1988. However, only the
newest generation of airplanes is
required to have fully tested and
certificated 16g seats. FAA
proposed a retrofit rule on October
4, 2002, to phase in 16g seats
fleetwide within 14 years after
adoption of the final rule.
Overhead bins
FAA issued an airworthiness directive requiring To improve the
corrective action for overhead bin designs found crashworthiness of
not to meet the existing rules.
some bins after
failures were
observed in a 1989
crash in Kegworth,
England.
Impact
The airworthiness directive to
improve bin connectors became
effective November 20, 1992, and
applied to Boeing 737 and 757
aircraft.
Fire
More stringent flammability In 1986, FAA upgraded the fire safety standards
standards for interior
for cabin interior materials in transport
materials
airplanes, establishing a new test method to
determine the heat release from materials
exposed to radiant heat and set allowable
criteria for heat release rates.
To give airliner cabin
occupants more time
to evacuate a burning
airplane by limiting
heat releases and
smoke emissions
when cabin interior
materials are
exposed to fire.
FAA required that all commercial
aircraft produced after August 20,
1988, have panels that exhibit
reduced heat releases and smoke
emissions to delay the onset of
flashover. Although there was no
retrofit of the existing fleet, FAA is
requiring that these improved
materials be used whenever the
cabin is substantially refurbished.
“Fire-blocking” seat
cushions
In 1984, FAA issued a regulation that enhanced To retard burning of
flammability requirements for seat cushions.
cabin materials to
increase evacuation
time.
Halon fire extinguishers
In March 1985, FAA issued a rule requiring at
least two Halon fire extinguishers on all
commercial airliners, in addition to other
required extinguishers
To extinguish in-flight This rule became effective April
fires.
29, 1985, and required
compliance by April 29, 1986.
Smoke detectors in
lavatories
In March 1985, FAA issued a rule requiring air
carriers to install smoke detectors in lavatories
within 18 months.
To identify and
extinguish in-flight
fires.
Fire extinguishers built in to In March 1985, FAA required air carriers to
lavatory waste receptacles install automatic fire extinguishers in the waste
paper bins in all aircraft lavatories.
Page 40
This rule applies to transport
category aircraft after November
26, 1987.
This rule became effective on April
29, 1985, and required
compliance by October 29, 1986.
To identify and
This rule became effective on April
extinguish prevent in- 29, 1985.
flight fires.
This rule required compliance by
April 29, 1987.
GAO-04-33 Airliner Cabin Occupant Safety and Health
Appendix III
Summary of Key Actions FAA Has Taken to Improve Airliner Cabin Safety and Health Since 1984
(Continued From Previous Page)
Key improvement areas
Action taken
Purpose
Cargo compartment
protection
In 1986, FAA upgraded the airworthiness
standards for ceiling and sidewall liner panels
used in cargo compartments of transport
category airplanes.
To improve fire safety This rule required compliance on
in the cargo and
March 20, 1998.
baggage
compartment of
certain transport
airplanes.a
Cargo compartment fire
In 1998, FAA required air carriers to retrofit the
detection and suppression U.S. passenger airliner fleet with fire detection
and suppression systems in certain cargo
compartments. This rule applied to over 3,400
airplanes in service and all newly manufactured
airplanes.
Status
To improve fire safety This rule became effective March
in the cargo and
19, 1998, requiring compliance on
baggage
March 20, 2001.
compartment of
certain transport
airplanes.a
Evacuation
Access to exits: Type III
exits
This rule requires improved access to the Type
III emergency exits (typically smaller, overwing
exits) by providing an unobstructed
passageway to the exit. Transport aircraft with
60 or more passenger seats were required to
comply with the new standards
To help ensure that
passengers have an
unobstructed
passageway to exits
during an
emergency.
This rule became effective June 3,
1992, requiring changes to be
made by December 3, 1992.
Public address system:
This rule requires that the public address
independent power source system be independently powered for at least
10 minutes and that at least 5 minutes of that
time is during announcements.
To eliminate reliance
on engine or
auxiliary-power-unit
operation for
emergency
announcements.
This rule became effective
November 27, 1989, for air carrier
and air taxi airplanes
manufactured on or after
November 27, 1990.
Exit row seating
This rule requires that persons seated next to
emergency exits be physically and mentally
capable of operating the exit and assisting other
passengers in emergency evacuations.
To improve
passenger
evacuation in an
emergency.
This rule became effective April 5,
1990, requiring compliance by
October 5, 1990.
Location of passenger
emergency exits
Rule issued to limit the distance between
adjacent emergency exits on transport
airplanes to 60 feet.
To improve
passenger
evacuation in an
emergency.
This rule became effective July 24,
1989, imposing requirements on
airplanes manufactured after
October 16, 1987.
Floor proximity emergency
escape path marking
Airplane emergency lighting systems must
visually identify the emergency escape path
and identify each exit from the escape path. To improve
passenger
evacuation when
smoke obscures
overhead lighting.
This rule became effective
November 26, 1984, requiring
implementation for large transport
airplanes by November 26, 1986.
Fire-resistant evacuation
slides
Emergency evacuation slides manufactured
after December 3, 1984, must be fire resistant
and comply with new radiant heat testing
procedures.b
To improve
passenger
evacuation.
This technical standard became
effective for all evacuation slides
manufactured after December 3,
1984.
General safety and health
Preparation for in-flight
emergencies
In 1986, FAA issued a rule requiring
To improve air
commercial airlines to carry emergency medical carriers’ preparation
kits.
for in-flight
emergencies.
Page 41
This rule became effective August
1, 1986, requiring compliance as
of that date.
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Appendix III
Summary of Key Actions FAA Has Taken to Improve Airliner Cabin Safety and Health Since 1984
(Continued From Previous Page)
Key improvement areas
Action taken
Purpose
Status
Ban on smoking for
majority of domestic
commercial flights
To limit the impact of These laws became effective in
In 1988 and 1989, the Congress passed
legislation banning smoking on domestic flights poor cabin air quality 1988, and 1990, respectively.
on occupants’ health
of varying durations.
Prevention of in-flight
injuries
In June 1995, following two serious events
involving turbulence, FAA issued a public
advisory to airlines urging the use of seat belts
at all times when passengers are seated but
concluded that existing rules did not require
strengthening.
To prevent passenger Information is currently posted on
FAA’s Web site.
injuries from
turbulence by
increasing public
awareness of the
importance of
wearing seatbelts.
In May 2000, FAA instituted the Turbulence
Happens public awareness campaign.
Source: GAO presentation of FAA information.
a
Technical Class C category cargo compartments are required to have built-in extinguishing systems to
control fire in lieu of crewmember accessibility. Class D category cargo compartments are required to
completely contain a fire without endangering the safety of the airplane occupants.
b
Standard Order (TSO)–C69B (‘‘Emergency Evacuation Slides, Ramps, Ramp/Slides, and
Slide/Rafts’’) prescribes minimum performance standards for emergency evacuation slides, ramps,
ramp/slides, and slide/rafts, including standards for resistance to radiant heat sources.
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Summaries of Potential Impact Safety
Advancements
This appendix presents information on the background and status of
potential advancements in impact safety that we identified, including the
following:
• retrofitting all commercial aircraft with more advanced seats,
• improving the ability of airplane floors to hold seats in an accident,
• preventing overhead luggage bins from becoming detached or opening,
• requiring child safety restraints for children under 40 pounds, and
• installing lap belts with self-contained inflatable air bags.1
Retrofitting All
Commercial Aircraft
with More Advanced
Seats
Background
In commercial transport airplanes, the ability of a seat to protect a
passenger from the forces of impact in an accident depends on reducing
the forces of impact to levels that a person can withstand, either by
spreading the impact over a larger part of the person’s body or by
decreasing the duration of the impact through the use of energy-absorbing
seats, an energy-absorbing fuselage and floors, or restraints such as seat
belts or inflatable seat belt air bags adapted from automobile technology. In
a 1996 study by R.G.W Cherry & Associates, enhancing occupant restraint
was ranked as the second most important of 33 potential ways to improve
air crash survivability.2 Boeing officials noted that the industry generally
1
Officials with the United Kingdom’s Civil Aviation Authority commented that inflatable
airbags are but one solution for providing upper torso restraint. These officials cited a
European Union funded “Going Safe” seat, which through an energy-absorbing device
enables a lap and diagonal belt system to be fitted to an unmodified seat rail.
2
R.G.W. Cherry & Associates, Analysis of Structural Factors Influencing the Survivability
of Occupants in Aeroplane Accidents, Civil Aviation Authority, Paper 96011 (London:
December 1996).
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agrees with this view but that FAA and the industry are at odds over the
means of implementing these changes.
According to an aviation safety expert, seats and restraints should be
considered as a system that involves
• the seats themselves,
• seat restraints such as seat belts,
• seat connections to the floor,
• the spacing between seats, and
• furnishings in the cabin area that occupants could strike in an accident.
To protect the occupant, a seat must not only absorb energy well but also
stay attached to the floor of the aircraft. In other words, the “tie-down”
chain must remain intact. Although aircraft seat systems are designed to
withstand about 9 to 16 times the force of gravity, the limits of human
tolerance to impact substantially exceed the aircraft and seat design limits.
A number of seat and restraint devices have been shown in testing to
improve survivability in aviation accidents. Several options are to retrofit
the entire current fleet with fully tested 16g seats, use rearward-facing
seats, require three-point auto-style seat belts with shoulder harnesses, and
install auto-style air bags.
FAA regulations require seats for newly certified airplane designs to pass
more extensive tests than were previously required to protect occupants
from impact forces of up to 16 times the force of normal gravity in the
forward direction; seat certification standards include specific
requirements to protect against head, spine, and leg injuries (see fig. 5).3
FAA first required 16g seats and tests for newly designed, certificated
3
The 1988 seat dynamic performance standards changed seat standards and testing. The
new standards expanded seat testing to include potential injuries caused by head strikes on
the back of seats and on stationary bulkheads, as well as criteria limiting lumbar and femur
loads. These limits, if exceeded, could cause injuries that could prevent evacuation. Seats
must be tested for forces in several directions to account for forward, downward, and other
directional movements such as may occur in an accident. Previous FAA regulations required
seats to be tested in only one primary direction at 9gs of force. The 16g level was adopted
rather than a higher standard because the floor tracks of many of the airplanes in use in 1988
would break away upon an impact of more than 16gs.
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airplanes in 1988; new versions of existing designs were not required to
carry 16g seats.4 Since 1988, however, in anticipation of a fleetwide retrofit
rule, manufacturers have increasingly equipped new airplanes with “16gcompatible” seats that have some of the characteristics of fully certified
16g seats.5 Certifying a narrow-body airplane type to full 16g seat
certification standards can cost $250,000.6,7
Figure 5: Coach Seating and Impact Position in Coach Seating
4
The initial proposed rule, Retrofit of Improved Seats in Air Carrier Transport-Category
Airplanes, 53 Fed. Reg. 17650 (1988) proposed requiring compliance with improved
crashworthiness standards for all seats of transport-category airplanes used under part 121
and part 135 and prohibiting the operation of these airplanes unless all seats met the
crashworthiness performance standards required by Improved Seat Safety Standards, 53
Fed. Reg. 17640 (1988).
5
In general, most 16g-compatible seats meet the structural requirements of the 16g seat rule
but do not need to meet the head injury criteria.
6
Each aircraft type typically has 8 to 10 different types of seats, each of which must be
certified; a typical economy class seat costs about $1,800. For marketing reasons, airlines
usually choose their own distinctive seats, which must be certified for each type of airplane
they fly.
7
According to a Boeing Official, one cost estimate compiled by ATA and the Aerospace
Industries Association in response to NPRM 88-8 presented in December 1988 showed the
recurring per program cost [was listed] at $440,000.
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In 1998 FAA estimated that 16g seats would avoid between about 210 to 410
fatalities and 220 to 240 serious injuries over the 20-year period from 1999
through 2018. A 2000 study funded by FAA and the British Civil Aviation
Authority estimated that if 16g seats had been installed in all airplanes that
crashed from 1984 through 1998, between 23 to 51 fewer U.S. fatalities and
18 to 54 fewer U.S. serious injuries would have occurred over the period. A
number of accidents analyzed in that study showed no benefit from 16g
seats because it was assumed that 16g seats would have detached from the
floor, offering no additional benefits compared with older seats.8
Worldwide, the study estimated, about 333 fewer fatalities and 354 fewer
serious injuries would have occurred during the period had the improved
seats been installed. Moreover, if fire risks had been reduced, the estimated
benefits of 16g seats might have increased dramatically, as more occupants
who were assumed to survive the impact but die in the ensuing fire would
then have survived both the impact and fire.9
Status
Seats that meet the 16g certification requirements are currently available
and have been required on newly certificated aircraft designs since 1988.
However, newly manufactured airplanes of older certification, such as
Boeing 737s, 757s, or 767s, were not required to be equipped with 16g
certified seats. Recently, FAA has negotiated with manufacturers to install
full 16g seats on new versions of older designs, such as all newly produced
737s.10 In October 2002, FAA published a new proposal to create a timetable
for all airplanes to carry fully certified 16g seats within 14 years.11 The
comment period for the currently proposed rule ended in March 2003.
8
R.G.W. Cherry & Associates, Benefit Analysis for Aircraft 16-g Dynamic Seats,
DOT/FAA/AR-00/13 (Washington, D.C.: April 2000). This study examined 25 large
commercial airplane accidents that occurred from 1984 and through 1998 and possibly
involved seat-related fatalities or injuries.
9
In commenting on the proposed 16g seat retrofit rule, Boeing noted that there were
fundamental, fatal flaws in both the analysis of benefits and the analysis of costs of
implementing this rule.
10
Until recently, FAA generally did not require a manufacturer to meet new, higher safety
standards that are put in place after the date the manufacturer applies for a type certificate
unless FAA can demonstrate that an unsafe condition exists. FAA’s changed product rule
requires manufacturers to comply with the latest airworthiness standards when significant
design changes are proposed for a derivative aircraft that will be certificated under an
amended or supplemental type certificate. 65 Fed. Reg. 36244 (2002).
11
Improved Seats in Air Carrier Transport Category Airplanes, 67 Fed. Reg. 62294 (2002).
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Under this proposal, airframe manufacturers would have 4 years to begin
installing 16g seats in newly manufactured aircraft only, and all airplanes
would have to be equipped with full 16g seats within 14 years or when
scheduled for normal seat replacement. FAA estimated that upgrading
passenger and flight attendant seats to meet full 16g requirements would
avert approximately 114 fatalities and 133 serious injuries over 20 years
following the effective date of the rule. This includes 36 deaths that would
be prevented by improvements to flight attendant seats that would permit
attendants to survive the impact and to assist more passengers in an
evacuation.
FAA estimated the costs to avert 114 fatalities and 133 serious injuries at
$245 million in present-value terms, or $519 million in overall costs, which,
according to FAA’s analysis, would approximate the monetary benefits
from the seats.12 FAA estimated that about 7.5 percent of airplane seats
would have to be replaced before they would ordinarily be scheduled for
replacement. FAA’s October 2002 proposal divides seats into three classes
according to their approximate performance level. Although FAA does not
know how many seats of each type seat are in service, it estimates that
about 44 percent of commercial-service aircraft are equipped with full 16g
seats, 55 percent have 16g-compatible seats, and about 1 percent have 9g
seats. The 16g-compatible or partial 16g seats span a wide range of
capabilities; some are nearly identical to full 16g seats but have been
labeled as 16g-compatible to avoid more costly certification, and other
partial 16g seats offer only minor improvements over the older generation
of 9g seats. To determine whether these seats have the same performance
characteristics as full 16g seats, it may be sufficient, in some cases, to
review the company’s certification paperwork; in other cases, however, full
crash testing of actual 16g seats may be necessary to determine the level of
protection provided.
FAA is currently considering the comments it received on its October 2002
proposal. Industry comments raised concerns about general costs, the
costs of retrofitting flight attendant seats, and the possibility that older
airplanes designed for 9g seats might require structural changes to
accommodate full 16g seats. One comment expressed the desire to give
some credit for and “grandfather” in at least some partial 16g seats.
12
FAA assumed benefits of $3 million for an averted fatality and $0.5 million for an averted
serious injury.
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Advancements
Improving the Ability
of Airplane Floors to
Hold Seats in an
Accident
Background
In an accident, a passenger’s chances of survival depend on how well the
passenger cabin maintains “living space” and the passenger is “tied down”
within that space. Many experts and reports have noted floor retention—
the ability of the aircraft cabin floor to remain intact and hold the
passenger’s seat and restraint system during a crash—as critical to
increasing the passenger’s chances of survival. Floor design concepts
developed during the late 1940s and 1950s form the basis for the cabin
floors found in today’s modern airplanes.
Accident investigations have documented failures of the floor system in
crashes.13 New 16g seat requirements were developed in the 1980s. 16g
seats were intended to be retrofitted on aircraft with traditional 9g floors
and were designed to maximize the capabilities of existing floor strength.
While 16g seats might be strong, they could also be inflexible and thus fail if
the floor deformed in a crash. Under the current 16g requirement, the seats
must remain attached to a deformed seat track and floor structure
representative of that used in the airplane.14 To meet these requirements,
the seat was expected to permanently deform to absorb and limit impact
forces even if the 16g test conditions were exceeded during a crash.
A major accident related to floor deformation occurred at Kegworth,
England, in 1989. A Boeing 737-400 airplane flew into an embankment on
approach to landing. In total, only 21 of the 52 triple seats—all “16gcompatible” —remained fully attached to the cabin floor; 14 of those that
remained attached were in the area where the wing passes through the
13
A study of survivable accidents that took place from 1970 through 1978 indicated that floor
deformation during a crash was a primary cause of seat failure in 60 percent of the
accidents. (Chandler, et al., DOT/FAA/CT-82-118)
14
In the dynamic 16g seat test with a deformed floor, one floor track must be pitched 10
degrees (up or down) relative to the other floor track, which must in turn be rolled 10
degrees.
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cabin and the area is stronger than other areas to support the wing.15 In this
section of the airplane, the occupants generally survived, even though they
were exposed to an estimated peak level of 26gs. The front part of the
airplane was destroyed, including the floor; most of these seats separated
from the airplane, killing or seriously injuring the occupants. An FAA
expert noted that the impact was too severe for the airplane to maintain its
structural integrity and that 16g seats were not designed for an accident of
that severity. The British Air Accidents Investigation Branch noted that
fewer injuries occurred in the accident than would probably have been the
case with earlier-generation seats. However, the Branch also noted that
“relatively minor engineering changes could significantly improve the
resilience and toughness of cabin floors . . . and take fuller advantage of the
improved passenger seats.” The Branch reported that where failures
occurred, it was generally the seat track along the floor that failed, and not
the seat, and that the rear attachments generally remained engaged with
the floor, “at least partially due to the articulated joint built into the rear
attachment, an innovation largely stemming from the FAA dynamic test
requirements.” The Branch concluded that “seats designed to these
dynamic requirements will certainly increase survivability” but “do not
necessarily represent an optimum for the long term . . . if matched with
cabin floors of improved strength and toughness.”16
Status
Several reports have recommended structural improvements to floors. A
case study of 11 major accidents for which detailed information was
available found floor issues to be a major cause of injury or fatalities in 4
accidents and a minor cause in 1 accident. Another study estimated the
past benefits of 16g seats in U.S. accidents between 1984 and 1998 and
found no hypothetical benefit from 16g seats in a number of accidents
because the floor was extensively disrupted during impact.17 In other
15
Some 16g-compatible seats were manufactured to meet 16g dynamic testing standards but
did not complete FAA’s certification process for floor deformation on representative floors
and seat tracks and technically met only the 9g seat certification requirements.
16
Report on the accident to Boeing 737-400 G-OBME near Kegworth, Leicestershire, on 8
January 1989, Aircraft Accident Report 4/90, AAIB, DOT, London, HMSO;
“Recommendations for Injury Prevention in Transport Aviation Accidents,” prepared for
NASA, Langley Research Center, by Simula Technologies, Inc., February 2, 2000, TR-99112,
S97324.
17
“Benefit Analysis for Aircraft 16-g Dynamic Seats,” Final Report, U.S. Department of
Transportation (DOT/FAA/AR-00/13) and U.K Civil Aviation Authority (CAA Paper 99003).
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words, unless the accidents had been less severe or the floor and seat
tracks had been improved beyond the 9g standard on both new and old jets,
newer 16g seats would not have offered additional benefits compared with
the older seats that were actually on the airplane during the accidents
under study.
A research program on seat and floor strength was recently conducted by
the French civil aviation authority, the Direction Générale de l’Aviation
Civile. Initial findings of the research program on seat-floor attachments
have not shown dramatic results and showed no rupture or plastic
deformation of any cabin floor parts during a 16g test. However, French
officials noted that they plan to perform additional tests with more rigid
seats. Because many factors are involved it is difficult to identify the
interrelated issues and interactions between seats and floors. A possible
area for future research, according to French officials, is to examine
dynamic floor warping during a crash to improve impact performance.
FAA officials said they have no plans to change floor strength
requirements. FAA regulations require floors to meet impact forces likely
to occur in “emergency landing conditions,” or generally about 9gs of
longitudinal static force. According to several experts, stronger floors
could improve the performance of 16g seats. In addition, further
improvement in seats beyond the 16g standard would likely require
improved floors.
Preventing Overhead
Storage Bin
Detachment to Protect
Passengers in an
Accident
Background
In an airplane crash, overhead luggage bins in the cabin sometimes detach
from their mountings along the ceiling and sidewalls and can fall
completely or allow pieces of luggage to fall on passengers’ heads (See fig.
6.). While only a few cases have been reported in which the impact from
dislodged overhead bins was the direct cause of a crash fatality or injury, a
study for the British Civil Aviation Authority that attempted to identify the
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specific characteristics of each fatality in 42 fatal accidents estimated that
the integrity of overhead bin stowage was the 17th most important of 32
factors used to predict passenger survivability.18 Maintaining the integrity
of bins may also help speed evacuation after a crash.
Safer bins have been designed since bin problems were observed in a
Boeing 737 accident in Kegworth, England, in 1989, when nearly all the bins
failed and fell on passengers. FAA tested bins in response to that accident.
The Kegworth bins were certified to the current FAA 9g longitudinal static
loading standards, among others. When FAA subsequently conducted
longitudinal dynamic loading tests on the types of Boeing bins involved, the
bins failed. Several FAA experts said that the overhead bins on 737s had a
design flaw. FAA then issued an airworthiness directive that called for
modifying all bins on Boeing 737 and 757 aircraft. The connectors for the
bins were strengthened in accordance with the airworthiness directive, and
the new bins passed FAA’s tests.
The British Air Accidents Investigation Branch recommended in 1990 that
the performance of both bins and latches be tested more rigorously,
including the performance of bins “when subjected to dynamic crash
pulses substantially beyond the static load factors currently required.”
NTSB has made similar recommendations.
Turbulence reportedly injures at least 15 U.S. cabin occupants a year, and
possibly over 100. Most of these injuries are to flight attendants who are
unrestrained. Some injuries are caused by luggage falling from bins that
open in severe turbulence. Estimates of total U.S. airline injuries from binrelated falling luggage range from 1,200 to 4,500 annually, most of which
occur during cruising rather than during boarding or disembarking.19
The study for the British Civil Aviation Authority noted above found that as
many as 70 percent of impact-related accidents involve overhead bins that
become detached. However, according to the report, bin detachment does
not appear to be a major factor in occupants’ survival and data are
insufficient to support a specific determination about the mechanism of
18
R.G.W. Cherry & Associates, Analysis of Structural Factors Influencing the Survivability
of Occupants in Aeroplane Accidents, Civil Aviation Authority, Paper 96011 (London:
December 1996).
19
Flight Safety Foundation, “Increased Amount and Types of Carry-On Baggage Bring New
Industry Responses,” November-December 1997, Vol. 32, No. 6, p. 6.
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failure. FAA has conducted several longitudinal and drop tests since the
Kegworth accident, including drops of airplane fuselage sections with
overhead storage bins installed. A 1993 dynamic vertical drop test showed
some varying bin performance problems at about 36gs of downward force.
An FAA longitudinal test in 1999 tested two types of bins at 6g, at the 9g
FAA certification requirement, and at the 16g level; in the 16g longitudinal
test, one of the two bins broke free from its support mountings.
Status
In addition to the requirement that they withstand forward (longitudinal)
loads of slightly more than 9gs, luggage bins must meet other directional
loading requirements.20 Bin standards are part of the general certification
requirements for all onboard objects of mass. FAA officials said that
overhead bins no longer present a problem, appear to function as designed,
and meet standards. An FAA official told us that problems such as those
identified at Kegworth have not appeared in later crashes. Another FAA
official said that while Boeing has had some record of bin problems, the
problems are occasional and quickly rectified through design changes.
Boeing officials told us that the evidence that bins currently have latch
problems is anecdotal.
Suggestions for making bins safer in an accident include adding features to
absorb impact forces and keep bins attached and closed during structural
deformation; using dynamic 16g longitudinal impact testing standards
similar to those for seats; and storing baggage in alternative compartments
in the main cabin, elsewhere in the aircraft, or under seats raised for that
purpose.
Child Safety Seats
Background
Using a correctly-designed child safety seat that is strapped in an airplane
seat offers protection to a child in an accident or turbulence (see fig. 6). By
contrast, according to many experts, holding a child under two years old on
an adult’s lap, which is permitted, is unsafe for both the child and for other
20
Bins are required to withstand 9g forward (longitudinal), 3g upward, 6g downward, and
other load requirements.
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occupants who could be struck by the child in an accident. Requiring child
safety seats for infants and small children on airplanes is one of NTSB’s
“most wanted” transportation safety improvements. The British Air
Accidents Investigation Branch made similar recommendations, as did a
1997 White House Commission report on aviation.
Figure 6: Examples of Child Safety Seats
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An FAA analysis of survivable accidents from 1978 through 1994 found that
9 deaths, 4 major injuries, and 8 minor injuries to children occurred. The
analysis also found that the use of child safety seats would have prevented
5 deaths, all the major injuries, and 4 to 6 of the minor injuries. Child safety
advocates have pointed to several survivable accidents in which children
died—a 1994 Charlotte, North Carolina, crash; a 1990 Cove Neck, New
York, accident; and a 1987 Denver, Colorado, accident—as evidence of the
need for regulation.
A 1992 FAA rule required airlines to allow child restraint systems, but FAA
has opposed mandatory child safety seats on the basis of studies showing
that requiring adults to pay for children’s seats would induce more car
travel, which the study said was more dangerous for children than airplane
travel. One study published in 1995 by DOT estimated that if families were
charged full fares for children’s seats, 20 percent would choose other
modes of transportation, resulting in a net increase of 82 deaths among
children and adults over 10 years.
If child safety seats are required, airlines may require adults wishing to use
child safety seats to purchase an extra seat for the child’s safety seat. FAA
officials told us that they could not require that the seat next to a parent be
kept open for a nonpaying child. However, NTSB has testified that the
scenarios for passengers taking other modes of transportation are flawed
because FAA assumed that airlines would charge full fares for infants
currently traveling free. NTSB noted in 1996 that airlines would offer
various discounts and free seats for infants in order to retain $6 billion in
revenue that would otherwise be lost to auto travel. Airlines have already
responded to parents who choose to use child restraint systems with
scheduling flexibility, and many major airlines offer a 50 percent discount
off any fare for a child under 2 to travel in an approved child safety seat.
The 1995 DOT study, however, estimated that even if a child’s seat on an
airplane were discounted 75 percent, some families would still choose car
travel and that the choice by those families to drive instead of fly would
result in a net increase of 17 child and adult deaths over 10 years.
In FAA tests, some but not all commercially available automobile child
restraint systems have provided adequate protection in tests simulating
airplane accidents. Prices range from less than $100 for a child safety seat
marketed for use in both automobiles and airplanes to as much as $1,300
for a child safety seat developed specifically for use in airplanes.
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A drawback to having parents, rather than airlines, provide child safety
seats for air travel is that some models may be more difficult to fit into
airplane seat belts, making a proper fit more challenging. While the
performance of standardized airline-provided seats may be better than that
of varied FAA-certified auto-airplane seats, one airline said that providing
seats could present logistical problems for them. However, Virgin Atlantic
Airlines supplies its own specially developed seats and prohibits parents
from using their own child seats. Because turbulence can be a more
frequent danger to unrestrained children than accidents, one expert told us
that a compromise solution might include allowing some type of alternative
in-flight restraint.
Status
Child safety seats are currently available for use on aircraft. The technical
issues involved in designing and manufacturing safe seats for children to
use in both cars and airplanes have largely been solved, according to FAA
policy officials and FAA researchers. Federal regulations establish
requirements for child safety seats designed for use in both highway
vehicles and aircraft by children weighing up to 50 pounds. FAA officials
explained that regulations requiring child safety seats have been delayed, in
part, because of public policy concerns that parents would drive rather
than fly if they were required to buy seats for their children. On February
18, 1998, FAA asked for comments on an advanced notice of proposed rulemaking to require the use of child safety seats for children under the age of
2. FAA sponsored a conference in December 1999 to examine child
restraint systems. At that conference, the FAA Administrator said the
agency would mandate child safety seats in aircraft and provide children
with the same level of safety as adults. FAA officials told us that they are
still considering requiring the use of child safety seats but have not made a
final decision to do so. If FAA does decide to provide “one level of safety”
for adults and children, as NTSB advocates, parents may opt to drive to
their destinations to avoid higher travel costs, thereby statistically
exposing themselves and their children to more danger. In addition, FAA
will have to decide whether the parents or airlines will provide the seats.
If FAA decides to require child safety seats, it will need to harmonize its
requirements with those of other countries where requirements differ, as
the regulations on child restraint systems vary. In Canada, as in the United
States, child safety seats are not mandatory on registered aircraft. In
Europe, the regulations vary from country to country, but no country
requires their use. Australia’s policy permits belly belts but discourages
their use. An Australian official said in 1999 that Australia was waiting for
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Summaries of Potential Impact Safety
Advancements
the United States to develop a policy in this area and would probably follow
that policy.
Inflatable Lap Belt Air
Bags
Background
Lap belts with inflatable air bags are designed to reduce the injuries or
death that may result when a passenger’s head strikes the airplane interior.
These inflatable seat belts adapt advanced automobile air bag technology
to airplane seats in the form of seat belts with embedded air bags. If a
passenger loses consciousness because of a head injury in an accident,
even a minor, nonfatal concussion can cause death if the airplane is
burning and the passenger cannot evacuate quickly. Slowing the duration
of the impact with an air bag lessens its lethality. According to a
manufacturer’s tests using airplane seats on crash sleds, lap belts with air
bags can likely reduce some impact injuries to survivable levels.21
FAA does not require seats to be tested in sled tests for head impact
protection when there would be “no impact” with another seat row or
bulkhead wall, such as when spacing is increased to 42 inches from the
more typical 35 inches. While more closely spaced economy class seat
rows can provide head impact protection through energy-absorbing seat
backs, seats in no impact positions have tested poorly in head injury
experiments, resulting in severe head strikes against the occupants’ legs or
the floor, according to the manufacturer. This no impact exemption from
FAA’s head injury criteria can include exit rows, business class seats, and
seats behind bulkhead walls and could permit as many as 30 percent of
seats in some airplanes to be exempt from the head impact safety criteria
that row-to-row seats must meet.
Status
According to the manufacturer, 13 airlines have installed about 1,000 of the
devices in commercial airliners, mainly at bulkhead seats; about 200 of
21
One manufacturer’s testing shows that the inflatable lap belts can reduce head injury
criteria scores from about 2,000 to 200-300 in a 16g impact. A score of 1,000 implies a skull
fracture, possible loss of consciousness, and a 16 percent risk of life-threatening brain
injury.
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these are installed in the U.S. fleet. All of the orders and installations so far
have been done to meet FAA’s seat safety regulations rather than for
marketing reasons, according to the manufacturer.
The airlines would appear to benefit from using the devices in bulkhead
seats if that would allow them to install additional rows of seats. While the
amount of additional revenue would depend on the airplane design and
class of seating, two additional seats may produce more net revenue per
year than the cost for the devices to be installed throughout an aircraft.22
Economic constraints are acquisition costs, maintenance costs, and
increased fuel costs due to weight. The units currently weigh about 3
pounds per seat, or 2 pounds more than current seat belts. According to the
manufacturer, the air bag lap belts currently cost $950 to $1,100, including
maintenance. The manufacturer estimated that if 5 percent of all U.S. seat
positions were equipped with the devices (about 50,000 seats per year), the
cost would drop to about $300 to $600 per seat, including installation.23
Lap belt air bags have been commercially available for only a few years.
FAA’s Civil Aerospace Medical Institute assisted the developers of the
devices; manufacturers for both passenger and military use (primarily
helicopter) are conducting ongoing research. FAA and other regulatory
bodies have no plans to require their installation, but airlines are allowed to
use them. The extent to which these devices are installed will depend on
each airline’s analysis of the cost and benefits.
22
At an annual life-cycle cost of approximately $12,000 to outfit an average airliner with lap
belt air bags on all seats of the U.S. fleet, assuming an installation cost of $450 per seat
position not including maintenance and replacement costs. A GAO analysis of the 2002
Annual Report of Southwest Airlines, which has relatively low passenger revenue per
available seat mile compared with other airlines, found that each seat produced an annual
net revenue of about $10,000. See appendix VIII for our analysis of the costs associated with
lap belts.
23
According to the manufacturer, the installation of the most common design requires
maintenance of one minute per seat position for a diagnostic test every 1,900 flight hours,
and the devices must be refurbished about once every 7 years at about a third of the initial
price.
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Advancements
This appendix presents information on the background and status of
potential advancements in fire safety that we identified, including the
following:
• preventing fuel tank explosions with fuel tank inerting;
• preventing in-flight fires with arc fault circuit breakers;
• identifying in-flight fires with multisensor fire and smoke detectors;
• suppressing in-flight and postcrash fires by using water mist fire
suppression systems;
• mitigating postcrash damage and injury by using less flammable fuels;
• mitigating in-flight and postcrash fires by using fire-resistant thermal
acoustic insulation;
• mitigating fire-related deaths and injuries by using ultra-fire-resistant
polymers; and
• mitigating fire deaths and injuries with sufficient airport rescue and fire
fighting.
Fuel Tank Inerting
Background
Fuel tank inerting involves pumping nitrogen-enriched air into an airliner’s
fuel tanks to reduce the concentration of oxygen to a level that will not
support combustion. Nitrogen gas makes a fuel tank safer by serving as a
fire suppressant. The process can be performed with both ground-based
and onboard systems, and it significantly reduces the flammability of the
center wing tanks, thereby lowering the likelihood of a fuel tank explosion.
Following the crash of TWA Flight 800 in 1996, in which 230 people died,
NTSB determined that the probable cause of the accident was an explosion
in the center wing fuel tank. The explosion resulted from the ignition of
flammable fuel vapors in this tank, which is located in the fuselage in the
space between the wing junctions. NTSB subsequently placed the
improvement of fuel tank design on its list of “Most Wanted Safety
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Improvements” and recommended that fuel tank inerting be considered an
option to eliminate the likelihood of fuel tank explosions.
FAA issued Special Federal Aviation Regulation 881 to eliminate or
minimize the likelihood of ignition sources by revisiting the fuel tank’s
design. Issued in 2001, the regulation consists of a series of FAA regulatory
actions aimed at preventing the failure of fuel pumps and pump motors,
fuel gauges, and electrical power wires inside these fuel tanks. In late 2002,
FAA amended the regulation to allow for an “equivalent level of safety” and
the use of inerting as part of an alternate means of compliance.
In a 2001 report, an Aviation Rule-making Advisory Committee tasked with
evaluating the benefits of inerting the center wing fuel tank estimated these
benefits in terms of lives saved. After projecting possible in-flight and
ground fuel tank explosions and postcrash fires from 2005 through 2020,
the committee estimated that 132 lives might be saved from a ground-based
system and 253 lives might be saved from an onboard system.2
Status
Neither of the two major types of fuel tank inerting—ground-based and
onboard—is currently available for use on commercial airliners because
additional development is needed.3 Both types offer benefits and
drawbacks.
• A ground-based system sends a small amount of nitrogen into the center
wing tank before departure. Its benefits include that (1) it requires no
new technology development for installation, (2) the tank can be inerted
in 20 minutes, and (3) it carries a lesser weight penalty. Its drawbacks
include that it is unable to inert for descent, landing, and taxiing to the
1
ATA noted that more than 80 fuel tank Airworthiness Directives have been adopted since
the crash of TWA Flight 800 and that a similar number of directives are currently under
development.
2
The committee also estimated, on the basis of data on nitrogen exposure from the
Occupational Safety and Health Administration and the National Institute of Occupational
Safety and Health, that from 24 to 81 lives could be lost over the same period, depending on
the degree of oxygen depletion. The report did not specifically indicate whether this
forecast was for a ground-based, onboard, hybrid, or any other inerting system.
3
By using more general terminology, this terminology excludes hybrid and liquid nitrogen
inerting systems, also considered by the Aviation Rule-making Advisory Committees for
their 1998 and 2001 reports.
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destination gate, and nitrogen supply systems are needed at each
terminal gate and remote parking area at every airport.
• An onboard system generates nitrogen by transferring some of the
engine bleed air – air extracted from the jet engines to supply the cabin
pressurization system in normal flight—through a module that separates
air into oxygen and nitrogen and discharges the nitrogen enriched air
into the fuel tank. Its benefits include that (1) it is self-reliant and (2) it
significantly reduces an airplane’s vulnerability to lightning, static
electricity, and incendiary projectiles throughout the flight’s duration.4
Its drawbacks include that it (1) weighs more, (2) increases the aircraft’s
operating costs, and (3) may decrease the aircraft’s reliability.5
According to FAA, its fire safety experts’ efforts to develop a lighter-weight
system for center wing tank inerting have significantly increased the
industry’s involvement. Boeing and Airbus are working on programs to test
inerting systems in flight. For example, Boeing has recently completed a
flight test program with a prototype system on a 747.
None of the U.S. commercial fleet is equipped with either ground-based or
onboard inerting systems, though onboard systems are in use in U.S. and
European military aircraft. Companies working in this field are focused on
developing new inerting technologies or modifying existing ones. A
European consortium is developing a system that combines onboard center
wing fuel tank inerting with sensors and a water-mist-plus-nitrogen fire
suppression system for commercial airplanes.
In late 2002, FAA researchers successfully ground-tested a prototype
onboard inerting system using current technology on a Boeing 747SP. New
research also enabled the agency to ease a design requirement, making the
inerting technology more cost-effective. This new research showed that
4
According to an FAA safety expert, FAA is addressing only the center wing tank because of
its significantly higher flammability exposure and the low risk of an explosion in the wing
tanks.
5
A current controversial issue is whether inerting technology will be considered flightcritical hardware—and therefore will be required to function properly for the aircraft to fly.
If it is deemed flight critical, its reliability may affect the dispatch rate of the aircraft. For
example, if the technology experiences operational problems, the aircraft may be allowed to
fly only 25 times a week, even if it is scheduled to fly 30 times a week. This problem reduces
revenue to the airline and is a greater concern for civilian than for military aviation, because
there are usually replacements for military aircraft.
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reducing the oxygen level in the fuel tank to 12 percent—rather than 9
percent, as was previously thought—is sufficient to prevent fuel tank
explosions in civilian aircraft.6 FAA also developed a system that did not
need the compressors that some had considered necessary. Together, these
findings allowed for reductions in the size and power demands of the
system.
FAA plans to focus further development on the more practical and costeffective onboard fuel tank inerting systems. For example, to further
improve their cost-effectiveness, the systems could be designed both to
suppress in-flight cargo fires, thereby allowing them to replace Halon
extinguishing agents, and to generate oxygen for emergency
depressurizations, thereby allowing them to replace stored oxygen or
chemical oxygen generators.
NASA is also conducting longer-term research on advanced technology
onboard inert gas-generating systems and onboard oxygen-generating
systems. Its research is intended (1) to develop the technology to improve
its efficiency, weight, and reliability and (2) to make the technology
practical for commercial air transport. NASA will fund the development of
emerging technologies for ground-based technology demonstration in
fiscal year 2004. NASA is also considering the extension of civilian
transport inerting technology to all fuel tanks to help protect airplanes
against terrorist acts during approaches and departures.
The cost of the system, its corresponding weight, and its unknown
reliability are the most significant factors affecting the potential use of
center wing fuel tank inerting. New cost and weight estimates are
anticipated in 2003.
6
FAA fuel tank safety experts conducted tests under high temperatures and found that a
tank with an oxygen level of 12 percent was inert against internal threats, such as sparks
and hot surfaces. According to one FAA expert, the system provides a “below 12 percent”
inert tank under all conditions except for a brief time during descent when local pockets in
the tank may approach 16 percent oxygen. The expert said that at this time, the tank is
generally cool enough to be nonflammable even with normal air (21 percent oxygen) in the
tank. If the tank is cool enough, internal threats will not ignite the fuel air mixture. He said
the probability of explosions is very low in the wing tanks because they are not heated by
other airplane systems.
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• In 2001, FAA estimated total costs to equip the worldwide fleet at $9.9
billion for ground-based, and $20.8 billion for onboard, inerting
systems.7
• In 2002, FAA officials developed an onboard system for B-747 flighttesting. The estimated cost was $460,000. The officials estimated that
each system after that would cost about $200,000. The weight of the FAA
prototype system is 160 pounds.8 A year earlier, NASA estimated the
weight for a B-777 system with technology in use in military aircraft at
about 550 pounds.9
Arc Fault Circuit
Breaker
Background
Arcing faults in wiring may provide an ignition source that can start fires.
Electrical wiring that is sufficiently damaged might cause arcing or direct
shorting resulting in smoking, overheating, or ignition of neighboring
materials. A review of data produced by FAA, the Airline Pilots Association,
and Boeing showed that electrical systems have been a factor in
approximately 50 percent of all aircraft occurrences involving smoke or
fire and that wiring has been implicated in about 10 percent of those
occurrences. In addition, faulty or malfunctioning wiring has been a factor
in at least 15 accidents or incidents investigated by NTSB since 1983.
Properly selecting, routing, clamping, tying, replacing, marking, separating,
and cleaning around wiring areas and proper maintenance all help mitigate
the potential for wire system failures, such as arcing, that could lead to
smoke, fire and loss of function. Chemical degradation, age induced
cracking, and damage due to maintenance may all create a scenario which
7
These estimates included the costs for modifying aircraft that are currently in service, in
production, and being designed, and they assumed a predicted reduction in the accident rate
of 75 percent.
8
This system does not have the capability to inert the cargo compartment, bay, and wheel
well, and it dumps oxygen as effluent rather than using it for an emergency passenger
oxygen system.
9
A 2001 NASA study indicated that two liquid nitrogen systems were the only ones that
appeared capable of inerting all fuel tanks of a commercial aircraft full time.
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could lead to arcing. Arcing can occur between a wire and structure or
between different wire types. Wire chafing is a sign of degradation; chafing
happens when the insulation around one wire rubs against a component
tougher than itself (such as structure or control cable) exposing the wire
conductor. This condition can lead to arcing. When arcing wires are too
close to flammable materials or are flammable themselves, fires can occur.
In general, wiring and wiring insulation degrade for a variety of reasons,
including age, inadequate maintenance, chemical contamination, improper
installation or repair, and mechanical damage. Vibration, moisture, and
heat can contribute to and accelerate degradation. Consequences of wire
systems failures include loss of function, smoke, and fire. Since most
wiring is bundled and located in hidden or inaccessible areas, it is difficult
to monitor the health of an aircraft’s wiring system during scheduled
maintenance using existing equipment and procedures. Failure
occurrences have been documented in wiring running to the fuel tank, in
the electronics equipment compartment, in the cockpit, in the ceiling of the
cabin, and in other locations.
To address the concerns with arcing, arc fault circuit breakers for aircraft
use are being developed. The arc fault circuit breaker cuts power off as it
senses a wire beginning to arc. It is intended to prevent significant damage
before a failure develops into a full-blown arc, which can produce
extremely localized heat, char insulation, and generally create problems in
the wire bundles. Arc fault circuit protection devices would mitigate arcing
events, but will not identify the wire breaches and degradation that
typically lead up to these events.
Status
FAA, the Navy, and the Air Force are jointly developing arc fault circuit
breaker technology. Boeing is also developing a monitoring system to
detect the status of and changes in wiring; and power shuts down when
arcing is detected. This system may be able to protect wiring against both
electrical overheating and arcing and is considered more advanced than the
government’s circuit breaker technology.
FAA developed a plan called the Enhanced Airworthiness Program for
Airplane Systems to address wiring problems, which includes development
of arc fault circuit breaker technology and installation guidance along with
proposals of new regulations. The plan provides means for enhancing
safety in the areas of wire system design, certification, maintenance,
research and development, reporting, and information sharing and
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outreach. FAA also tasked an Aging Transport Systems Rule-making
Advisory Committee to provide data, recommendations, and evaluation
specifically on aging wiring systems. The new regulations being considered
are entitled the Enhanced Airworthiness Program for Airplane Systems
Rule and are expected by late-2005. Under this rule-making package,
inspections would evaluate the health of wiring and all of its components
for operation, such as connectors and clamps. Part of the system includes
visual inspections of all wiring within arm’s reach, enhanced by the use of
hand-held mirrors. This improvement is expected to catch more wiring
flaws than current visual inspection practices. Where visual inspections
can not be assumed to detect damage, detailed inspections will be required.
The logic process to establish proper inspections is called the Enhanced
Zonal Analysis Procedure, which will be issued as an Advisory Circular.
This procedure is specifically directed towards enhancing the maintenance
programs for aircraft whose current program does not include tasks
derived from a process that specifically considers wiring in all zones as the
potential source of ignition of a fire.
Additional development and testing will be required before advanced arc
fault circuit breakers will be available for use on aircraft. The FAA
currently is in the midst of a prototype program where arc fault circuit
breakers are installed in an anticollision light system on a major air
carrier’s Boeing 737. The FAA and the Navy are currently analyzing tests of
the circuit breakers to assess their reliability. The Society of Automotive
Engineers is in the final stages of developing a Minimum Operating
Performance Specification for the arc fault circuit breaker.
Multisensor Detectors
Background
Multisensor detectors, or “electronic noses,” could combine one or more
standard smoke detector technologies; a variety of sensors for detecting
such gases as carbon monoxide, carbon dioxide, or hydrocarbon; and a
thermal sensor to more accurately detect and locate overheated or burning
materials. The sensors could improve existing fire detection by discovering
and locating potential or actual fires sooner and reducing the incidence of
false alarms. These “smart” sensors would ignore the “nuisance sources”
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such as dirt, dust, and condensation that are often responsible for
triggering false alarms in existing systems.10
According to studies by FAA and the National Institute of Standards and
Technology, many current smoke and fire detection systems are not
reliable. A 2000 FAA study indicated that cargo compartment detection
systems, for example, resulted in at least one false alarm per week from
1988 through 1990 and a 200:1 ratio of false alarms to actual fires in the
cargo compartment from 1995 through 1999. 11 FAA has since estimated a
100:1 cargo compartment false alarm ratio, partly because reported actual
incidents have increased According to FAA’s Service Difficulty Report
database,12 about 990 actual smoke and fire events were reported for
2001.13
Multisensor detectors could be wired or wireless and linked to a
suppression system. One or several sensor signals or indicators could
cause the crew to activate fire extinguishers in a small area or zone, a
larger area, or an entire compartment, resulting in a more appropriate and
accurate use of the fire suppressant. For example, in areas such as the
avionics compartment, materials that can burn are relatively well-defined.
Multisensor detectors the size of a postage stamp could be designed to
detect smoldering fires in cables or insulation or in overheated equipment
in that area. Placing the detectors elsewhere in the airplane could improve
the crew’s ability to respond to smoke or fire, including occurrences in
hidden or inaccessible areas.
Improved sensor detection technologies would both enhance safety by
increasing crews’ confidence in the reliability of alarms and reduce costs
by avoiding the need to divert aircraft in response to false alarms. One
10
One type of smart sensor would analyze the light-scattering properties of the particles in
the air to differentiate between smoke particles and nuisance sources.
11
Aircraft Cargo Compartment Smoke Detector Alarm Incidents on U.S.-Registered
Aircraft, 1974-1999, DOT/FAA/AR-TN00/29 (Washington, D.C.: June 2000). The study
indicated a generally increasing number of false alarms as the size of the fleet grew.
12
Operating requirements for all aircraft have been amended by a 2000 final rule, whose
deadline was recently extended for the third time, to report the occurrence or detection of
failures, malfunctions, or defects concerning fire warning systems and false warnings of fire
or smoke in the entire U.S. fleet.
13
According to FAA fire safety experts, most of these are contaminated air or smoke events
in the cabin, detected by people, not by detectors.
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study estimated the average cost of a diversion at $50,000 for a wide-body
airplane and $30,000 for a narrow-body airplane. A diversion can also
present safety concerns because of the possible increased risk of an
accident and injuries to passengers and crew if there is (1) an emergency
evacuation, (2) a landing at an unfamiliar airport, (3) a change to air traffic
patterns, (4) a shorter runway, (5) inferior fire-fighting capability, (6) a loss
of cargo load, or (7) inferior navigation aids. In 2002, 258 unscheduled
landings due to smoke, fire, or fumes occurred. In addition, 342 flights were
interrupted; some of these flights had to return to the gate or abort a
takeoff.
FAA established basic detector performance requirements in 1965 and
1980. Detectors were to be made and installed in a manner that ensured
their ability to resist, without failure, all vibration, inertia, and other loads
to which they might normally be subjected; they also had to be unaffected
by exposure to fumes, oil, water, or other fluids. Regulations in 1986 and
1998 further defined basic location and performance requirements for
detectors in different areas of the cargo compartment. In 1998, FAA issued
a requirement for detection and extinguishment systems for one class of
cargo compartments, which relied on oxygen starvation to control fires.
This requirement significantly increased the number of detectors in use.
Status
Multisenor detectors are not currently available because additional
research is needed. Although they have been demonstrated in the
laboratory and on the ground, they have not been flight-tested. FAA and
NASA have multisensor detector research and development efforts under
way and are working to develop “smart” sensors and criteria for their
approval. FAA will also finish revising an Advisory Circular that establishes
test criteria for detection systems, designed to ensure that they respond to
fires, but not to nonfire sources. In addition, several companies currently
market “smart” detectors, mostly for nonaviation applications. For
example, thermal detection systems sense and count certain particles that
initially boil off the surface of smoldering or burning material.
A European consortium has been developing a system, FIREDETEX, that
combines the use of multisensor detectors, onboard fuel tank inerting, and
water-mist-plus-nitrogen fire suppression systems for commercial
airplanes. This program and associated studies are still ongoing and flight
testing is planned for the last quarter of calendar year 2003. The results of
tests on this system are expected to be made public in early 2004, and will
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help to clarify the possible costs, benefits, and drawbacks of the combined
system.
Additional research, development, and testing will be required before
multisensor technology is ready for use in commercial aviation. NASA,
FAA, and private companies are pursuing various approaches. Some
experts believe that some forms of multisensor technology could be in use
in 5 years. When these units become available, questions may arise about
where their use will be required. For example, the Canadian Transportation
Safety Board has recommended that some areas in addition to those
currently designated as fire zones may need to be equipped with
detectors.14 These include the electronics and equipment bay (typically
below the floor beneath the cockpit and in front of the passenger cabin),
areas behind interior wall panels in the cockpit and cabin areas, and areas
behind circuit breaker and other electronic panels.
Water Mist Fire
Suppression
Background
For over two decades, the aviation industry has evaluated the use of
systems that spray water mist to suppress fires in airliner cabins, cargo
compartments, and engine casings (see fig. 7). This effort was prompted, in
part, by a need to identify an alternative to Halon, the primary chemical
used to extinguish fires aboard airliners. With few exceptions, Halon is the
sole fire suppressant installed in today’s aircraft fire suppression systems.
However, the production of Halon was banned under the 1987 Montreal
Protocol on Substances that Deplete the Ozone Layer, and its use in many
noncritical sectors has been phased out. Significant reserves of Halon
remain, and its use is still allowed in certain “critical use” applications,
such as aerospace,15 because no immediate viable replacement agent
14
This recommendation was one of several resulting from the Canadian Transportation
Safety Board’s investigation of the Swissair Flight 111 crash.
15
A use is considered “critical” when a need exists to protect against fire or explosion risks
in areas that would result in a serious threat to essential services or pose an unacceptable
threat to life, the environment, or national security. Typical critical users are aerospace,
certain petrochemical production processors, certain marine applications, and national
defense.
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exists. To enable the testing and further development of suitable
alternatives to and substitutes for Halon, FAA has drafted detailed
standards for replacements in the cargo and engine compartments. These
standards typically require replacement systems to provide the same level
of safety as the currently used Halon extinguishing system.
Figure 7: Water Mist Nozzle and Possible Placement
According to FAA and others in the aviation industry, successful water mist
systems could provide benefits against an in-flight or postcrash fire,
including
• cooling the passengers, cabin surfaces, furnishings and overall cabin
temperatures;
• decreasing toxic smoke and irritant gases; and
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• delaying or preventing “flashover” fires from occurring. 16
In addition, a 1996 study prepared for the British Civil Aviation Authority
examined 42 accidents and 32 survivability factors and found that cabin
water spray was the factor that showed the greatest potential for reducing
fatality and injury rates.17 In the early 1990s, a joint FAA and Civil Aviation
Authority study found that cabin water mist systems would be highly
effective in improving survivability during a postcrash fire.18 However, the
cost of using these systems outweighed the benefits, largely because of the
weight of the water that airliners would be required to carry to operate
them. In the mid- and late-1990s, FAA and others began examining water
mist systems in airliner cargo compartments to help offset the cost of a
cabin water mist system because the water could be used or shared by both
the cargo compartment and the cabin. European and U.S. researchers also
designed systems that required much less water because they targeted
specific zones within an aircraft to suppress fires rather than spraying
water throughout the cabin or the cargo compartment.
In 2000, Navy researchers found a twin-fluid system to be highly reliable
and maintenance-free.19 Moreover, this system’s delivery nozzles could be
installed without otherwise changing cabin interiors. The Navy
researchers’ report recommended that FAA and NTSB perform follow-up
testing leading to the final design and certification of an interior water mist
fire suppression system for all passenger and cargo transport aircraft. Also
in 2000, a European consortium began a collaborative research project
16
Flashover can occur in an airplane cabin fire when all exposed combustible surfaces reach
ignition temperature more or less simultaneously. It is characterized by rapid increases in
temperature, with smoke, toxic gases, and oxygen depletion creating a largely
nonsurvivable environment.
17
R.G.W. Cherry & Associates, Analysis of Structural Factors Influencing the Survivability
of Occupants in Aeroplane Accidents, Civil Aviation Authority, Paper 96011 (London:
December 1996).
18
Increasing the Survival Rate in Aircraft Accidents: Impact Protection, Fire
Survivability, and Evacuation, European Transport Safety Council (December 1996).
19
Twin-fluid systems use air, nitrogen, or another gas in combination with water. They
require lower water supply pressure and bigger nozzle orifices.
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called FIREDETEX, which combines multisensor fire detectors, water
mist, and onboard fuel tank inerting into one fire detection and suppression
system.20
In 2001 and 2002, FAA tested experimental mist systems to determine what
could meet its preliminary minimum performance standards for cargo
compartment suppression systems. A system that combines water mist
with nitrogen met these minimum standards. In this system, water and
nitrogen “knock down” the initial fire, and nitrogen suppresses any deepseated residual fire by inerting the entire compartment.21 In cargo
compartment testing, this system maintained cooler temperatures than had
either a plain water mist system or a Halon-based system.
Status
Additional research and testing are needed before water mist technology
can be considered for commercial aircraft. For example, the weight and
relative effectiveness of any water mist system would need to be
considered and evaluated. In addition, before it could be used in aircraft,
the consequences of using water will need to be further evaluated. For
example, Boeing officials noted that using a water mist fire suppression
system in the cabin in a post crash fire might actually reduce passenger
safety if the mist or fog creates confusion among the passengers, leading to
longer evacuation times. Further, of concern is the possible shorting of
electrical wiring and equipment and damage to aircraft interiors (e.g., seats,
entertainment equipment, and insulation). Water cleanup could also be
difficult and require special drying equipment.
20
Inerting involves reducing flammability in fuel tanks, which is discussed separately in this
report.
21
Boeing commented that this more recent system would not pass the original cargo
minimum performance standard, and Boeing disagrees with FAA’s relaxing of the original
standard.
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Fire-Safe Fuels
Background
Burning fuel typically dominates and often overwhelms postcrash fire
scenarios and causes even the most fire-resistant materials to burn.22 Fuel
spilled from tanks ruptured upon crash impact often forms an easily
ignitable fuel-air mixture. A more frequent fuel-related problem is the fuel
tank explosion, in which a volatile fuel-air mixture inside the fuel tank is
ignited, often by an unknown source. For example, it is believed that fuel
tank explosions destroyed a Philippines Air 737 in 1990, TWA Flight 800 in
1996, and a Thai Air 737 in 2001. Therefore, reducing the flammability of
fuel could improve survivability in postcrash fires as well as reduce the
occurrence of fuel tank explosions.
Reducing fuel flammability involves limiting the volatility23 of fuel and the
rate at which it vaporizes.24 Liquid fuel can burn only when enough fuel
vapor is mixed with air. If the fuel cannot vaporize, a fire cannot occur. This
principle is behind the development of higher-flashpoint fuel, whose use
can decrease the likelihood of a fuel tank explosion. The flash point is the
lowest temperature at which a liquid fuel produces enough vapor to ignite
in the presence of a source of ignition—the lower the flash point, the
greater the risk of fire. If the fuel is volatile enough, however, and air is
sucked into the fuel tank area upon crash impact, limiting the fuel’s
vaporization can prevent a burnable mixture from forming. This principle
supports the use of additives that modify the viscosity of fuel to limit
postcrash fires; for example, antimisting kerosene contains such additives.
22
An average widebody aircraft carries 50,000 gallons of aviation fuel at takeoff.
23
Fuels function by releasing combustible gases. Indicators of volatility include a fuel’s
boiling point (the higher the boiling point, the less volatile the fuel) and vapor pressure (the
higher the vapor pressure, the more volatile the fuel). Therefore, raising the temperature
can increase volatility. A highly volatile fuel is more likely to form a flammable or explosive
mixture with air than a nonvolatile fuel. By definition, gases are volatile. Liquid fuels either
are sufficiently volatile at room temperature to produce combustible vapor (ethanol, petrol)
or they produce sufficient combustible vapors when heated (kerosene).
24
The fuel vaporization rate is the minimum temperature to which the pure liquid fuel must
be heated so that the vapor pressure is high enough for an explosive mixture to be formed
with air--then the liquid is allowed to evaporate and is brought into contact with a flame,
spark, or hot filament. Flash points are lower than ignition temperatures.
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According to FAA and NASA, however, these additives do nothing to
prevent fuel tank explosions.
From the early 1960s to the mid-1980s, FAA conducted research on fuel
safety. The Aviation Safety Act of 1988 required that FAA undertake
research on low-flammability aircraft fuels, and, in 1993, FAA developed
plans for fuel safety research. In 1996, a National Research Council experts’
workshop on aviation fuel summarized existing fuel safety research efforts.
The participants concluded that although postcrash fuel-fed aircraft fires
had been researched, limited progress had been achieved and little work
had been published.
As part of FAA’s research, fuels have been modified with thickening
polymer additives to slow down vaporization in crashes. Participants in
the 1996 National Research Council workshop identified several long-term
research goals for consideration in developing modified fuels and fuel
additives to improve fire safety. They also agreed that a combination of
effective fire-safe fuel additives could probably be either selected or
designed, provided that fuel performance requirements were identified in
advance. In addition, they agreed that existing aircraft designs that reduce
the chance of fuel igniting do not present major barriers to the
implementation of a fire-safe fuel.
A 1996 European Transport Safety Council report suggested that
antimisting kerosene be at least partially tested on regular military
transport flights (e.g., in one tank, feeding one engine) to demonstrate its
operational compatibility. The report also recommended the consideration
of a study comparing the costs of the current principal commercial fuel and
the special, higher-flashpoint fuel used by the Navy. According to NASA and
FAA fire-safe fuels experts, military fuel is much harder to burn in storage
or to ignite in a pan because of its lower volatility; however, it is just as
flammable as aviation fuel when it is sprayed into an engine combustor.
Status
Fire-safe fuels are not currently available and are in the early stages of
research and development. In January 2002, NASA opened a fire-safe fuels
research branch at its Glenn Research Center in Ohio. NASA-Glenn is
conducting aviation fuel research that evaluates fuel vapor flammability in
conjunction with FAA’s fuel tank inerting program, including the
measurement of fuel “flash points.” NASA is examining the effects of
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surfactants, gelling agents, and chemical composition changes on the
vaporization and pressure characteristics of jet fuel.25
In addition to FAA’s and NASA’s research, some university and industry
researchers have made progress in developing fire-safe fuels. Many use
advanced analytical, computational modeling technologies to inform their
research. A council of producers and users of fuels is also coordinating
research on ways to use such fuels. NASA fuel experts remain optimistic
that small changes in fuel technologies can have a big impact on fuel safety.
Developing fire-safe fuels will require much more research and testing.
There are significant technical difficulties associated with creating a fuel
that meets aviation requirements while meaningfully decreasing the
flammability of the fuel.
Thermal Acoustic
Insulation Materials
Background To keep an airplane quieter and warmer, a layer of thermal acoustic
insulation material is connected to paneling and walls throughout the
aircraft. This insulation, if properly designed, can also prevent or limit the
spread of an in-flight fire. In addition, thermal acoustic insulation provides
a barrier against a fire burning through the cabin from outside the
airplane’s fuselage (See fig. 8.). Such a fire, often called a postcrash fire,
may occur when fuel is spilled on the ground after a crash or an impact.
25
A surfactant, or surface-active agent, is a soluble compound that reduces the surface
tension of liquids, or reduces interfacial tension between two liquids or a liquid and a solid.
A gelling agent is a fuel “thickener.”
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Figure 8: Fire Insulation Blankets
While this thermal acoustic insulation material could help prevent the
spread of fire, some of the insulation materials that have been used in the
past have contributed to fires. For example, FAA indicated that an
insulation material, called metallized Mylar®, contributed to at least six inflight fires. Airlines have stopped using this material and are removing it
from existing aircraft.
FAA’s two main efforts in this area are directed toward preventing fatal inflight fire and improving postcrash fire survivability.
• Since 1998, FAA has been developing test standards for preventing inflight fires in response to findings that fire spread on some thermal
acoustic insulation blanket materials. In 2000, FAA issued a notice of
proposed rule-making that outlined new flammability test criteria for inflight fires. FAA’s in-flight test standards require thermal acoustic
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insulation materials to protect passengers. According to the standards,
insulation materials installed in airplanes will not propagate a fire if
ignition occurs.
• FAA is also developing more stringent burnthrough test standards for
postcrash fires. FAA has been studying the penetration of the fuselage
by an external fire—known as fuselage burnthrough—since the late
1980s and believes that improving the fire resistance of thermal acoustic
insulation could delay fuselage burnthrough. In laboratory tests
conducted from 1999 through 2002, an FAA-led working group
determined that insulation is the most potentially effective and practical
means of delaying the spread of fire or creating a barrier to burnthrough.
In 2002, FAA completed draft burnthrough standards outlining a
proposed methodology for testing thermal acoustic insulation. The
burnthrough standards would protect passengers and crews by
extending by at least 4 minutes the time available for evacuation in a
postcrash fire.
Various studies have estimated the potential benefits from both test
standards:
• A 1999 study of worldwide aviation accidents from 1966 through 1993
estimated that about 10 lives per year would have been saved if
protection had provided an additional 4 minutes for occupants to exit
the airplane.
• A 2000 FAA study estimated that about 37 U.S. fatalities would be
avoided between 2000 and 2019 through the implementation of both
proposed standards.26
• A 2002 study by the British Civil Aviation Authority of worldwide
aviation accidents from 1991 through 2000 estimated that at least 34
lives per year would have been saved if insulation had met both
proposed standards.
26
FAA’s benefit estimate, based on $2.7 million per life saved, ranges from $37.7 million to
$231.5 million, discounted to present value, based partially on 37.2 deaths avoided from its
2000 study. FAA could not quantify benefits from flame propagation requirements, but
indicated that avoiding an accident with 169 passenger fatalities would avert a $231.5
million loss (not including the cost of the plane).
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Status
Insulation designed to replace metallized Mylar® is currently available. A
2000 FAA airworthiness directive gave the airlines 5 years to remove and
replace metallized Mylar® insulation in 719 affected airplanes.
Replacement insulation is required to meet the in-flight standard and will
be installed in these airplanes by mid-2005. In that airworthiness directive,
FAA indicated that it did not consider other currently installed insulation to
constitute an unsafe condition.
Thermal acoustic insulation is currently available for installation on
commercial airliners. This insulation has been demonstrated to reduce the
chance of fatal in-flight fires and to improve postcrash fire survivability. On
July 31, 2003, FAA issued a final rule requiring that after September 2, 2005,
all newly manufactured airplanes having a seating capacity of more than 20
passengers or over 6,000 pounds must use thermal acoustic insulation that
meets more stringent standards for how quickly flames can spread.27 In
addition, for aircraft of this size manufactured before September 2, 2003,
replacement insulation in the fuselage must also meet the new, higher
standard.
Research is continuing to develop thermal acoustic insulation that provides
better in-flight and burnthrough protection. Even when this material is
available, the high cost of retrofitting airplanes may limit its use to newly
manufactured aircraft. For example, FAA estimates that the metallized
Mylar® retrofit alone will cost a total of $368.4 million, discounted to
present value terms, for the 719 affected airplanes. Because thermal
acoustic insulation is installed throughout the pressurized section of the
airplane for the life of its service, retrofitting the entire fleet would cost
several billion dollars.
Ultra-Fire-Resistant
Polymers
Background
Polymers are used in aircraft in the form of lightweight plastics and
composites and are selected on the basis of their estimated installed cost,
27
Improved Flammability Standards for Thermal/Acoustic Insulation Materials Used in
Transport Category Airplanes; Final Rule, FAA/DOT (14 C.F.R. parts 25, 91, et al.).
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weight, strength, and durability. Most of the aircraft cabin is made of
polymeric material. In the event of an in-flight or a postcrash fire, the use of
polymeric materials with reduced flammability could give passengers and
crew more time to evacuate by delaying the rate at which the fire spreads
through the cabin.
FAA researchers are developing better techniques to measure the
flammability of polymers and to make polymers that are ultra fire resistant.
Developing these materials is the long-term goal of FAA’s Fire Research
Program, which, if successful, will “eliminate burning cabin materials as a
cause of death in aircraft accidents.” Materials being improved include
composite and adhesive resins, textile fibers, rubber for seat cushions, and
plastics for molded parts used in seats and passenger electronics. (See fig.
9.)
Figure 9: Flammable Cabin Materials and Small-scale Material Test Device
Adding flame-retardant substances to existing materials is one way to
decrease their flammability. For example, some manufacturers add
substances that release water when they reach a high temperature. When a
material, such as wiring insulation, is heated or burns, the water acts to
absorb the heat and cools down the fire. Other materials are designed to
become surface-scorched on exposure to fire, causing a layer of char to
protect the rest of the material from burning. Lastly, adding a type of clay
can have a flame-retardant effect. In general, these fire-retardant polymers
are formulated to pass an ignition test but do not meet FAA’s criterion for
ultra fire resistance, which is a 90 percent reduction in the rate at which the
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untreated material would burn. To meet this strict requirement, FAA is
developing new “smart” polymers that are typical plastics under normal
conditions but convert to ultra-fire-resistant materials when exposed to an
ignition source or fire.
FAA has adopted a number of flammability standards over the last 30 years.
In 1984, FAA passed a retrofit rule that replaced 650,000 seat cushions with
flame-retardant seat cushions at a total cost of about $75 million. The
replacement seat cushions were found to delay cabin flashover by 40 to 60
seconds. Fire-retardant seat cushions can also prevent ramp and in-flight
fires that originate at a seat and would otherwise burn out of control if left
unattended. In 1986 and 1988, FAA set maximum allowable levels of heat
and smoke from burning interior materials to decrease the amount of
smoke that they would release in a postcrash fire. These standards affected
paneling in all newly manufactured aircraft. Airlines and airframe
manufacturers invested several hundred million dollars to develop these
new panels.
Status
Ultra-fireresistant polymers are not currently available for use on
commercial airliners. These polymers are still in the early stages of
research and development. To reduce the cost and simplify the testing of
new materials, FAA is employing a new technique to characterize the
flammability and thermal decomposition of new products; this technique
requires only a milligram of sample material. The result has been the
discovery of several new compositions of matter (including “smart”
polymers). The test identifies key thermal and combustion properties that
allow rapid screening of new materials.28 From these materials, FAA plans
to select the most promising and work with industry to make enough of the
new polymers to fabricate full-scale cabin components like sidewalls and
stowage bins for fire testing.
FAA’s phased research program includes the selection in 2003 of a small
number of resins, plastics, rubbers, and fibers on the basis of their
functionality, cost, and potential to meet fire performance guidelines. In
2005, FAA plans to fabricate decorative panels, molded parts, seat
cushions, and textiles for testing from 2007 through 2010. Full-scale testing
28
These methods test the heat release rate, total heat of combustion of the volatiles, thermal
stability, char yield, decomposition process, and rate of decomposition.
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is scheduled for 2011 but is contingent upon the availability of program
funds and commercial interest from the private sector.
Research continues on ultra-fire-resistant polymers that will increase
protection against in-flight fires and cabin burnthrough. According to an
FAA fire research expert, issues facing this research include (1) the current
high cost of ultra-fire-resistant polymers; (2) difficulties in producing ultrafire-resistant polymers with low to moderate processing temperatures,
good strength and toughness, and colorability and colorfastness; and (3)
gaps in understanding the relationship between material properties and fire
performance and between chemical composition and fire performance,
scaling relationships, and fundamental fire-resistance mechanisms. In
addition, once the materials are developed and tested, getting them
produced economically and installed in aircraft will become an issue. It is
expected that such new materials with ultra fire resistance would be more
expensive to produce and that the market for such materials would be
uncertain.
Airport Rescue and
Fire-Fighting
Operations
Background
Because of the fire danger following a commercial airplane crash, having
airport rescue and fire-fighting operations available can improve the
chances of survival for the people involved. Most airplane accidents occur
during takeoff or landing at the airport or in the surrounding community. A
fire outside the airplane, with its tremendous heat, may take only a few
minutes to burn through the airplane’s outside shell. According to FAA,
firefighters are responsible for creating an escape path by spraying water
and chemicals on the fire to allow the passengers and crew to evacuate the
airplane. Firefighters use one or more trucks to extinguish external fires,
often at great personal risk, and use hand-held attack lines when
attempting to put out fires within the airplane fuselage. (See fig. 10). Fires
within the fuselage are considered difficult to control with existing
equipment and procedures because they involve complex conditions, such
as smoke-laden toxic gases and high temperatures in the passenger cabin.
FAA has taken actions to control both internal and external postcrash fires,
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including requiring major airports to have airport rescue and fire-fighting
operations.
Figure 10: Airport Rescue and Fire Training
In 1972, FAA first proposed regulations to ensure that major airports have a
minimal level of airport rescue and fire-fighting operations. Some changes
to these regulations were made in 1988. The regulations establish, among
other things, equipment standards, annual testing requirements for
response times, and operating procedures. The requirements depend on
both the size of the airport and the resources the locality has agreed to
make available as needed.
In 1997, FAA compared airport rescue and fire-fighting missions and
standards for civilian airports with DOD’s for defense installations and
reported that DOD’s requirements were not applicable to civilian airports.
In 1988, and again in 1998, Transport Canada Civil Aviation also studied its
rescue and fire-fighting operations and concluded that the expenditure of
resources for such unlikely occurrences was difficult to justify from a
benefit-cost perspective. This conclusion highlighted the conflict between
safety and cost in attempting to define rescue and fire-fighting
requirements.
A coalition of union organizations and others concerned about aviation
safety released a report critical of FAA’s standards and operational
regulations in 1999. According to the report, FAA’s airport rescue and firefighting regulations were outdated and inadequate.
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Status
In 2002, FAA incorporated measures recommended by NTSB into FAA’s
Aeronautical Information Manual Official Guide to Basic Flight
Information and Air Traffic Control Procedures.29 These measures (1)
designate a radio frequency at most major airports to allow direct
communication between airport rescue and fire-fighting personnel and
flight crewmembers in the event of an emergency and (2) specify a
universal set of hand signals for use when radio communication is lost.
In March 2001, FAA responded to the reports criticizing its airport rescue
and fire-fighting standards by tasking its Aviation Regulatory Advisory
Committee to review the agency’s rescue and fire-fighting requirements to
identify measures that could be added, modified, or deleted. In 2003, the
committee is expected to propose requirements for the number of trucks,
the amount of fire extinguishing agent, vehicle response times, and staffing
at airports and to publish its findings in a notice of proposed rule-making.
Depending on the results of this FAA review, additional resources may be
needed at some airports. The overall cost of improving airport rescue and
fire-fighting response capabilities could be a significant barrier to the
further development of regulations. For example, some in the aviation
industry are concerned about the costs of extending requirements to
smaller airports and of appropriately equipping all airports with resources.
According to FAA, extending federal safety requirements to some smaller
airports would cost at least $2 million at each airport initially and $1 million
annually thereafter.
29
This manual is designed to provide the aviation community with basic flight information
and air traffic control procedures for use in the National Airspace System of the United
States.
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Summaries of Potential Improved Evacuation
Safety Advancements
This appendix presents information on the background and status of
potential advancements in evacuation safety that we identified, including
the following:
• improved passenger safety briefings;
• exit seat briefings;
• photo-luminescent floor track marking;
• crewmember safety and evacuation training;
• acoustic attraction signals;
• smoke hoods;
• exit slide testing;
• overwing exit doors;
• evacuation procedures for very large transport aircraft; and
• personal flotation devices.
Passenger Safety
Briefings
Background Federal regulations require that passengers receive an oral briefing prior to
takeoff on safety aspects of the upcoming flight. FAA also requires that oral
briefings be supplemented with printed safety briefing cards that pertain
only to that make and model of airplane and are consistent with the air
carrier’s procedures. These two safety measures must include information
on smoking, the location and operation of emergency exits, seat belts,
compliance with signs, and the location and use of flotation devices. In
addition, if the flight operates above 25,000 feet mean sea level, the briefing
and cards must include information on the emergency use of oxygen.
FAA published an Advisory Circular in March 1991 to guide air carriers’
development of oral safety briefings and cards. Primarily, the circular
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defines the material that must be covered and suggests material that FAA
believes should be covered. The circular also discusses the difficulty in
motivating passengers to attend to the safety information and suggests
making the oral briefing and safety cards as attractive and interesting as
possible to increase passengers’ attention. The Advisory Circular suggests,
for example, that flight attendants be animated, speak clearly and slowly,
and maintain eye contact with the passengers. Multicolored safety cards
with pictures and drawings should be used over black and white cards.
Finally, the circular suggests the use of a recorded videotape briefing
because it ensures a complete briefing with good diction and allows for
additional visual information to be presented to the passengers. (See fig.
11.)
Figure 11: Airline Briefing to Passengers on Safety Briefing Cards
Status Despite efforts to improve passengers’ attention to safety information, a
large percentage of passengers continue to ignore preflight safety briefings
and safety cards, according to a study NTSB conducted in 1999. Of 457
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passengers polled, 54 percent (247) reported that they had not watched the
entire briefing because they had seen it before. An additional 70 passengers
indicated that the briefing provided common knowledge and therefore
there was no need to watch it. Of 431 passengers who answered a question
about whether they had read the safety card, 68 percent (293) indicated
that they had not, many of them stating that they had read safety cards on
previous flights.
Safety briefings and cards serve an important safety purpose for both
passengers and crew. They are intended to prepare passengers for an
emergency by providing them with information about the location and
operation of exits and emergency equipment that they may have to
operate—and whose location and operation may differ from one airplane
to the next. Well-briefed passengers will be better prepared in an
emergency, thereby increasing their chances of surviving and lessening
their dependence on the crew for assistance.
In its emergency evacuation study, NTSB recommended that FAA instruct
airlines to “conduct research and explore creative and effective methods
that use state-of-the-art technology to convey safety information to
passengers.”1 NTSB further recommended “the presented information
include a demonstration of all emergency evacuation procedures, such as
how to open the emergency exits and exit the aircraft, including how to use
the slides.” That research found that passengers often view safety briefings
and cards as uninteresting and the information as intuitive. FAA has
requested that commercial carriers explore different ways to present the
materials to their passengers, adding that more should be done to educate
passengers about what to do after an accident has occurred.
Exit Seat Briefing
Background
Passengers seated in an exit row may be called on to assist in an
evacuation. Upon a crewmember’s command or a personal assessment of
danger, these passengers must decide if their exit is safe to use and then
open their exit hatch or door for use during an evacuation. In October 1990,
1
NTSB, Safety Study: Emergency Evacuation of Commercial Airlines, [A-00-86]
(Washington, D.C.: 2001).
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FAA required airlines to actively screen passengers occupying exit seats for
“suitability” and to administer one-on-one briefings on their
responsibilities. This rule does not require specific training for exit seat
occupants, but it does require that the occupants be duly informed of their
distinct obligations.
Status
According to NTSB, preflight briefings of passengers in exit rows could
contribute positively to a passenger evacuation. In a 1999 study, NTSB
found that the individual briefings given to passengers who occupy exit
seats have a positive effect on the outcome of an aircraft evacuation. The
studies also found that as a result of the individualized briefings, flight
attendants were better able to assess the suitability of the passengers
seated in the exit seats.
According to FAA’s Flight Standards Handbook Bulletin for Air
Transportation, several U.S. airlines have identified specific cabin
crewmembers to perform “structured personal conversations or briefings,”
designed to equip and prepare passengers in exit seats beyond the general
passenger briefing. Also, the majority of air carriers have procedures to
assist crewmembers with screening passengers seated in exit rows.
FAA’s 1990 rule requires that passengers seated in exit rows be provided
with information cards that detail the actions to be taken in the case of an
emergency. However, individual exit row briefings, such as those
recommended by NTSB, are not required. Also included on the information
cards are provisions for a passenger who does not wish to be seated in the
exit row to be reseated. Additionally, carriers are required to assess the exit
row passenger’s ability to carry out the required functions. The extent of
discussion with exit row passengers depends on each airline’s policy.
Photo-luminescent
Floor Track Marking
Background
In June 1983, an Air Canada DC-9 flight from Dallas to Toronto was cruising
at 33,000 feet when the crew reported a lavatory fire. An emergency was
declared, and the aircraft made a successful emergency landing at the
Cincinnati Northern Kentucky International Airport. The crew initiated an
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evacuation, but only half of the 46 persons aboard were able to escape
before becoming overcome by smoke and fire. In its investigation of this
accident, NTSB learned that many of the 23 passengers who died might
have benefited from floor tracking lighting. As a result, NTSB
recommended that airlines be equipped with floor-level escape markings.
FAA determined that floor lighting could improve the evacuation rate by 20
percent under certain conditions, and FAA now requires all airliners to
have a row of lights along the floor to guide passengers to the exit should
visibility be reduced by smoke.
On transport category aircraft, these escape markings, called floor
proximity marking systems, typically consist primarily of small electric
lights spaced at intervals on the floor or mounted on the seat assemblies,
along the aisle. The requirement for electricity to power these systems has
made them vulnerable to a variety of problems, including battery and
wiring failures, burned-out light bulbs, and physical disruption caused by
vibration, passenger traffic, galley cart strikes, and hull breakage in
accidents. Attempts to overcome these problems have led to the proposal
that nonelectric, photo-luminescent (glow-in-the-dark) materials be used in
the construction of floor proximity marking systems. The elements of these
new systems are “charged” by the normal airplane passenger cabin lighting,
including the sunlight that enters the cabin when the window shades are
open during daylight hours. (See fig. 12.)
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Figure 12: Floor Track Marking Using Photo-luminescent Materials
Status
Floor track marking using photo-luminescent materials is currently
available but not required for U.S. commercial airliners. Performance
demonstrations of photo-luminescent technology have found that
strontium aluminate photo-luminescent marking systems can be effective
in providing the guidance for egress that floor proximity marking systems
are intended to achieve. According to industry and government officials,
such photo-luminescent marking systems are also cheaper to install than
electric light systems and require little to no maintenance. Moreover,
photo-luminescent technology weighs about 15 to 20 pounds less than
electric light systems and, unlike the electric systems, illuminates both
sides of the aisle, creating a pathway to the exits.
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Photo-luminescent floor track marking technology is mature and is
currently being used by a small number of operators, mostly in Europe. In
the United States, Southwest Airlines has equipped its entire fleet with the
photo-luminescent system. However, the light emitted from photoluminescent materials is not as bright as the light from electrically operated
systems. Additionally, the photo-luminescent materials are not as effective
when they have not been exposed to light for an extended period of time,
as after a long overseas nighttime flight. The estimated retail price of an
entire system, not including the installation costs, is $5,000 per airplane.
Crewmember Safety
and Evacuation
Training
Background
FAA requires crewmembers to attend annual training to demonstrate their
competency in emergency procedures. They have to be knowledgeable and
efficient while exercising good judgment. Crewmembers must know their
own duties and responsibilities during an evacuation and be familiar with
those of their fellow workers so that they can take over for others if
necessary.
The requirements for emergency evacuation training and demonstrations
were first established in 1965. Operators were required to conduct fullscale evacuation demonstrations, include crewmembers in the
demonstrations, and complete the demonstrations in 2 minutes using 50
percent of the exits. The purpose of the demonstrations was to test the
crewmembers’ ability to execute established emergency evacuation
procedures and to ensure the realistic assignment of functions to the crew.
A full-scale demonstration was required for each type and model of
airplane when it first started passenger-carrying operations, increased its
passenger seating capacity by 5 percent or more, or underwent a major
change in the cabin interior that would affect an emergency evacuation.
Subsequently, the time allowed to evacuate the cabin during these tests was
reduced to 90 seconds.
The aviation community took steps in the 1990s to develop a program
called Crew Resource Management that focuses on overall improvements
in crewmembers’ performance and flight safety strategies, including those
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for evacuation. FAA officials told us that they plan to emphasize the
importance of effective communication between crewmembers and are
considering updating a related Advisory Circular. Effective communication
between cockpit and cabin crew are particularly important with the added
security precautions being taken after September 11, 2001, including the
locking the cockpit door during flight.
Status
The traditional training initiative now has an advanced curriculum,
Advanced Crew Resource Management. According to FAA, this
comprehensive implementation package includes crew resource
management procedures, training for instructors and evaluators, training
for crewmembers, a standardized assessment of the crew’s performance,
and an ongoing implementation process. This advanced training was
designed and developed through a collaborative effort between the airline
and research communities. FAA considers training to be an ongoing
development process that provides airlines with unique crew resource
management solutions tailored to their operational demands. The design of
crew resource management procedures is based on principles that require
an emphasis on the airline’s specific operational environment. The
procedures were developed to emphasize these crew resource
management elements by incorporating them into standard operating
procedures for normal as well as abnormal and emergency flight situations.
Because commercial airliner accidents are rare, crewmembers must rely
on their initial and recurrent training to guide their actions during an
emergency. Even in light of advances and initiatives in evacuation
technology, such as slides and slide life rafts, crewmembers must still
assume a critical role in ensuring the safe evacuation of their passengers.
Airline operators have indicated that it is very costly for them to pull large
numbers of crewmembers off-line to participate in training sessions.
FAA officials told us that improving flight and cabin crew communication
holds promise for ensuring the evacuation of passengers during an
emergency. To improve this communication and coordination between
flight and cabin crew, FAA plans to update the related Advisory Circular,
oversee training, and charge FAA inspectors with monitoring air carriers
during flights to see that improvements are being implemented. In addition,
FAA is enhancing its guidance to air carriers on preflight briefings for flight
crews to sharpen their responses to emergency situations and mitigate
passengers’ confusion. FAA expects this guidance to bolster the use and
quality of preflight briefings between pilots and flight attendants on
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security, communication, and emergency procedures. According to FAA,
these briefings have been shown to greatly improve the flight crew’s safety
mind-set and to enhance communication.
Acoustic Attraction
Signals
Background
Acoustic attraction signals make sounds to help people locate the doors in
smoke, darkness, or when lights and exit signs are obscured. When
activated, the devices are intended to help people to determine the
direction and approximate distance of the sound—and of the door.
Examples of audio attraction signals include recorded speech sounds,
broadband multifrequency sounds (“white noise”), or alarm bells.
Research to determine if acoustic attraction signals can be useful in aircraft
evacuation has included, for example, FAA’s Civil Aeromedical Institute
testing of recorded speech sounds in varying pitches, using phrases such as
“This way out,” “This way,” and “Exit here.” Researchers at the University
of Leeds developed Localizer Directional Sound beacons, which combine
broadband, multifrequency “white noise” of between 40Hz and 20kHz with
an alerting sound of at least one other frequency, according to the inventor
(see fig. 13).
Figure 13: Test Installation of Acoustic Signalling Device
Note: Acoustic signaling device is of the type used near building exits.
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The FAA study noted above of acoustic attraction signals found that in the
absence of recorded speech signals, the majority of participants evacuating
a low-light-level, vision-obscured cabin will head for the front exit or will
follow their neighbors. In contrast, participants exposed to recorded
speech sounds will select additional exits, even those in the rear of the
airplane. During aircraft trials conducted by Cranfield University and
University of Greenwich researchers, tests of directional sound beacons
found that under cabin smoke conditions, exits were used most efficiently
when the cabin crew gave directions and the directional sound beacons
were activated. With this combination, the distribution of passengers to the
available exits was better than with cabin crew directions alone, sound
beacons alone, no cabin crew directions, or no sound beacons.
Researchers found that passengers were able to identify and move toward
the closest sound source inside the airplane cabin and to distinguish
between two closely spaced loudspeakers. However, in 2001, Airbus
conducted several evacuation test trials of audio attraction signals using an
A340 aircraft. According to Airbus, the acoustic attraction signals did not
enhance passengers’ orientation, and, overall, did not contribute to
passengers’ safety.
Status While acoustic attraction signals are currently available, further research is
needed to determine if their use is warranted on commercial airliners. FAA,
Transport Canada Civil Aviation, and the British Civilian Aviation Authority
do not currently mandate the use of acoustic attraction signals. The United
Kingdom’s Air Accidents Investigation Branch made a recommendation
after the fatal Boeing 737 accident at Manchester International Airport in
1985 that research be undertaken to assess the viability of audio attraction
signals and other evacuation techniques to assist passengers impaired by
smoke and toxic or irritant gases. The Civilian Aviation Authority accepted
the recommendation and sponsored research at Cranfield University;
however, it concluded from the research results that the likely benefit of
the technology would be so small that no further action should be taken,
and the recommendation was closed in 1992.
The French Direction Generale de l’Aviation Civile funded aircraft
evacuation trials using directional sound beacons in November 2002, with
oversight by the European Joint Aviation Authorities. The trials were
conducted at Cranfield University’s evacuation simulator with British
Airways cabin crew and examined eight trial evacuations by two groups of
‘passengers.’ The study surveyed the participants’ views on various aspects
of their evacuation experience and measured the overall time to evacuate.
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The speed of evacuation was found to be biased by the knowledge
passengers’ gained in the four successive trials, and by variations in the
number of passengers participating on the 2 days (155 and 181). The four
trials by each of the two groups of passengers also involved different
combinations of crew and sound in each. The study concluded that the
insufficient number of test sessions further contributed to bias in the
results, and that further research would be needed to determine whether
the devices help to speed overall evacuation.
Further research and testing are needed before acoustic attraction signals
can be considered for widespread airline use. The signals may have
drawbacks that would need to be addressed. For example, the Civil
Aviation Authority found that placing an audio signal in the bulkhead might
disorient or confuse the first few passengers who have to pass and then
move away from the sound source to reach the exit. Such hesitation slowed
passengers’ evacuation during testing. The researchers at Cranfield
University trials in 1990 concluded that an acoustic sound signal did not
improve evacuation times by a statistically significant amount, suggesting
that the device might not be cost-effective.
Smoke Hoods Background
Smoke hoods are designed to provide the user with breathable, filtered air
in an environment of smoke and toxic gases that would otherwise be
incapacitating. More people die from smoke and toxic gases than from fire
after an air crash. Because only a few breaths of the dense, toxic smoke
typically found in aircraft fires can render passengers unconscious and
prevent their evacuation, the wider use of smoke hoods has been
investigated as a means of preventing passengers from being overcome by
smoke and of giving them enough breathable air to evacuate. However,
some studies have found that smoke hoods are only effective in certain
types of fires and in some cases may slow the evacuation of cabin
occupants.
As shown in figure 14, a filter smoke hood can be a transparent bag worn
over the head that fits snugly at the neck and is coated with fire-retardant
material; it has a filter but no independent oxygen source and can provide
breathable air by removing some toxic contaminants from the air for a
period ranging from several minutes to 15 minutes, depending on the
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severity and type of air contamination. The hood has a filter to remove
carbon monoxide—a main direct cause of death in fire-related commercial
airplane accidents, as well as hydrogen cyanide—another common cause
of death, sometimes from incapacitation that can prevent evacuation.
Hoods also filter carbon dioxide, chlorine, ammonia, acid gases such as
hydrogen chloride and hydrogen sulfide, and various hydrocarbons,
alcohols, and other solvents. Some hoods also include a filter to block
particulate matter. One challenge is where to place the hoods in a highly
accessible location near each seat.
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Figure 14: An Example of a Commercially Available Smoke Hood
Certain smoke hoods have been shown to filter out many contaminants
typically found in smoke from an airplane cabin fire and to provide some
temporary head protection from the heat of fire. In a full-scale FAA test of
cabin burnthrough, toxic gases became the driving factor determining
survivability in the forward cabin, reaching lethal levels minutes before the
smoke and temperature rose to unsurvivable levels.
A collaborative effort to estimate the potential benefits of smoke hoods
was undertaken in 1986 by the British Civil Aviation Authority (CAA), the
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Federal Aviation Administration, the Direction Générale de l’Aviation Civile
(France) and Transport Canada Civil Aviation. The resulting 1987 study
examined the 20 accidents where sufficient data was available out of 74
fire-related accidents worldwide from 1966 to 1985. The results were
sensitive to assumptions regarding extent of use and delays due to putting
on smoke hoods. The study concluded that smoke hoods could
significantly extend the time available to evacuate an aircraft and would
have saved approximately 179 lives in the 20 accidents studied, assuming
no delay in donning smoke hoods. Assuming a 10 percent reduction in the
evacuation rate due to smoke hood use would have resulted in an
estimated 145 lives saved in the 20 accidents with adequate data. A 15
second delay in donning the hoods would have saved an estimated 97 lives
in the 20 accidents.2 When the likelihood of use of smoke hoods was
included in the analysis for each accident, the total net benefit was
estimated at 134 lives saved in the 20 accidents. The study also estimated
that an additional 228 lives would have been saved in the 54 accidents
where less data was available, assuming no delay in evacuation.3
The U.S. Air Force and a major manufacturer are developing a drop-down
smoke hood with oxygen. Because current oxygen masks in airplanes are
not airtight around the mouth, they provide little protection from toxic
gases and smoke in an in-flight fire. To provide protection from these
hazards, as well as from decompression and postcrash fire and smoke, the
Air Force’s drop-down smoke hood with oxygen uses the airplane’s existing
oxygen system and can fit into the overhead bin of a commercial airliner
where the oxygen mask is normally stowed. This smoke hood is intended
to replace current oxygen masks but also be potentially separated from the
oxygen source in a crash to provide time to evacuate.
Status
Smoke hoods are currently available and produced by several
manufacturers; however, not all smoke hoods filter carbon monoxide. They
are in use on many military and private aircraft, as well as in buildings. An
2
These estimates assume 100 percent smoke hood use. The net 97 lives saved with a 15
second delay assumes that smoke hoods would have saved lives in six accidents and cost
lives in four; the net 145 lives saved with a 10 percent reduction in the evacuation rate
assumes that smoke hoods would have saved lives in six accidents and cost lives in two.
3
“Smoke Hoods: Net Safety Benefit Analysis,” a collaborative effort by the Civil Aviation
Authority, Federal Aviation Administration, Direction Générale de l’Aviation Civile, and
Transport Canada, London, November 1987, CAA Paper 87017.
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individually-purchased filter smoke hood costs about $70 or more, but
according to one manufacturer bulk order costs have declined to about $40
per hood. In addition, they estimated that hoods cost about $2 a year to
install and $5 a year to maintain. They weigh about a pound or less and
have to be replaced about every 5 years. Furthermore, airlines could incur
additional replacement costs due to theft if smoke hoods were placed near
passenger seats in commercial aircraft.
Neither the British CAA, the FAA, the DGAC, nor Transport Canada Civil
Aviation has chosen to require smoke hoods. The British Air Accident
Investigations Branch recommended that smoke hoods be considered for
aircraft after the 1985 Manchester accident, in which 48 of 55 passengers
died on a runway from an engine fire before takeoff, mainly from smoke
inhalation and the effects of hydrogen cyanide. Additionally, a U.K.
parliamentary committee recommended research into smoke hoods in
1999, and the European Transport Safety Council, an international
nongovernmental organization whose mission is to provide impartial
advice on transportation safety to the European Commission and
Parliaments, recommended in 1997 that smoke hoods be provided in all
commercial aircraft. Canada’s Transportation Safety Board has taken no
official position on smoke hoods, but has noted a deficiency in cabin safety
in this area and recommended further evaluation of voluntary passenger
use.
Although smoke hoods are currently available, they remain controversial.
Passengers are allowed to bring filter type smoke hoods on an airplane, but
FAA is not considering requiring airlines to provide smoke hoods for
passengers. The debate over whether smoke hoods should be installed in
aircraft revolves mainly around regulatory concerns that passengers will
not be able to put smoke hoods on quickly in an emergency; that hoods
might hinder visibility, and that any delay in putting on smoke hoods would
slow down an evacuation. FAA’s and CAA’s evacuation experiments—to
determine how long it takes for passengers to unpack and don smoke
hoods and whether an evacuation would be slowed by their use—have
reached opposite conclusions about the effects of smoke hoods on
evacuation rates. The CAA has noted that delays in putting on smoke hoods
by only one or two people could jeopardize the whole evacuation. An
opposite view by some experts is that the gas and smoke-induced
incapacitation of one or two passengers could also delay an evacuation.
FAA believes that an evacuation might be hampered by passengers’
inability to quickly and effectively access and don smoke hoods, by
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competitive passenger behavior, and by a lack of passenger attentiveness
during pre-flight safety briefings. FAA noted that smoke hoods can be
difficult to access and use even by trained individuals. However, other
experts have noted that smoke hoods might reduce panic and help make
evacuations more orderly, that competitive behavior already occurs in
seeking access to exits in a fire, and that passengers could learn smoke
hood safety procedures in the pre-flight safety briefings in the same way
they learn to use drop-down oxygen masks or flotation devices.
The usefulness of smoke hoods varies across fire scenarios depending on
assumptions about how fast hoods could be put on and how much time
would be available to evacuate. One expert told us that the time needed to
put on a smoke hood might not be important in several fire scenarios, such
as an in-flight fire in which passengers are seeking temporary protection
from smoke until the airplane lands and an evacuation can begin. In other
scenarios—a ground evacuation or postcrash evacuation — some experts
argue that passengers in back rows or far from an exit may have their exit
path temporarily blocked as other passengers exit and, because of the
delay in their evacuation, may have a greater need and more time available
to don smoke hoods than passengers seated near usable exits.
Exit Slide Testing
Background
Exit slide systems are rarely used during their operational life span.
However, when such a system is used, it may be under adverse crash
conditions that make it important for the system to work as designed. To
prevent injury to passengers and crew escaping through floor-level exits
located more than 6 feet above the ground, assist devices (i.e., slides or
slide-raft systems) are used. (See fig. 15.)
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Figure 15: Drawing of Possible Emergency Slide Testing of FAA’s 747 Test Aircraft
The rapid deployment, inflation, and stability of evacuation slides are
important to the effectiveness of an aircraft’s evacuation system, as was
illustrated in the fatal ground collision of a Northwest Airlines DC-9 and a
Northwest Airlines 727 in Romulus, Michigan, in December 1990. As a
result of the collision, the DC-9 caught fire, but there were several slide
problems that slowed the evacuation. For example, NTSB later found that
the internal tailcone exit release handle was broken, thereby preventing the
tailcone from releasing and the slide from deploying.
Because of concerns about the operability of exit slides, NTSB
recommended in 1974 that FAA improve its maintenance checks of exit
slide operations. In 1983, FAA revised its exit slide requirements to specify
criteria for resistance to water penetration and absorption, puncture
strength, radiant heat resistance, and deployment as flotation platforms
after ditching.
Status
All U.S. air carriers have an FAA-approved maintenance program for each
type of airplane that they operate. These programs require that the
components of an airplane’s emergency evacuation system, which includes
the exit slides, be periodically inspected and serviced. An FAA principal
maintenance inspector approves the air carrier’s maintenance program.
According to NTSB, although most air carriers’ maintenance programs
require that a percentage of emergency evacuation slides or slide rafts be
tested for deployment, the percentage of required on-airplane deployments
is generally very small. For example, NTSB found that American Airlines’
FAA-approved maintenance program for the A300 requires an on-airplane
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operational check of four slides or slide rafts per year. Delta Air Lines’ FAAapproved maintenance program for the L-1011 requires that Delta activate a
full set of emergency exits and evacuation slides or slide rafts every 24
months. Under an FAA-approved waiver for its maintenance program,
United is not required to deploy any slide on its 737 airplanes.
NTSB also found that FAA allows American Airlines to include inadvertent
and emergency evacuation deployments toward the accomplishment of its
maintenance program; therefore, it is possible that American would not
purposely deploy any slides or slide rafts on an A300 to comply with the
deployment requirement during any given year. In addition, NTSB found
that FAA also allows Delta Air Lines to include inadvertent and emergency
evacuation deployments toward the accomplishment of its maintenance
program.
NTSB holds that because inadvertent and emergency deployments do not
occur in a controlled environment, problems with, or failures in, the system
may be more difficult to identify and record, and personnel qualified to
detect such failures may not be present. For example, in an inadvertent or
emergency slide or slide raft deployment, observations on the amount of
time it takes to inflate the slide or slide raft, and the pressure level of the
slide or slide raft are not likely to be documented. For these reasons, a 1999
NTSB report said that FAA’s allowing these practices could potentially
leave out significant details about the interaction of the slide or slide raft
with the door or how well the crew follows its training mock-up
procedures. Accordingly, in 1999, NTSB recommended that FAA stop
allowing air carriers to count inadvertent and emergency deployments
toward meeting their maintenance program requirement because
conditions are not controlled and important information (on, for example,
the interface between the airplane and the evacuation slide system, timing,
durability, and stability) is not collected. The recommendation continues to
be open at the NTSB. NTSB officials said they would be meeting to discuss
this recommendation with FAA in the near future.
Additionally, NTSB recommended that FAA, for a 12-month period, require
that all operators of transport-category aircraft demonstrate the onairplane operation of all emergency evacuation systems (including the
door-opening assist mechanisms and slide or slide raft deployment) on 10
percent of each type of airplane (at least one airplane per type) in their
fleets. NTSB said that these demonstrations should be conducted on an
airplane in a controlled environment so that qualified personnel can
properly evaluate the entire evacuation system. NTSB indicated that the
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results of the demonstrations (including an explanation of the reasons for
any failures) should be documented for each component of the system and
should be reported to FAA.4
Overwing Exit Doors Background
Prompted by a tragedy in which 57 of the 137 people on board a British
Airtours B-737 were killed because passengers found exit doors difficult to
access and operate, the British Civil Aviation Authority initiated a research
program to explore changes to the design of the overwing exit (Type III)
door.
Trained crewmembers are expected to operate most of the emergency
equipment on an airplane, including most floor-level exit doors. But
overwing exit doors, termed “self-help exits,” are expected to be and will
primarily be opened by passengers without formal training.5 NTSB reported
that even when flight attendants are responsible for opening the overwing
exit doors, passengers are likely to make the first attempt to open the
overwing exit hatches because the flight attendants are not physically
located near the overwing exits.
There are now two basic types of overwing exit doors—the “self-help”
doors that are manually removed inward and then stowed and the newer
“swing out” doors that open outward on a hinge.
According to NTSB, passengers continue to have problems removing the
inward-opening exit door and stowing it properly. The manner in which the
overwing exit is opened and how and where the hatch should be stowed is
not intuitively obvious to passengers, nor is it easily or consistently
depicted graphically. NTSB recently recommended to FAA that Type III
overwing exits on newly manufactured aircraft be easy and intuitive to
4
NTSB, Emergency Evacuation of Commercial Airplanes, 2001, [A-00-76] (Washington,
D.C.:2000).
5
The overwing exit hatch can weigh as much as 65 pounds and be 20 inches wide and 36
inches high.
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open and have automatic stowage out of the egress path.6 NTSB has
indicated that the semiautomatic, fast-opening, Type III overwing exit
hatch could give passengers additional evacuation time.
Status
Over-wing exit doors that “swing out” on hinges rather than requiring
manual removal are currently available. The European Joint Aviation
Authorities (JAA) has approved the installation of these outward-opening
hinged doors on new-production aircraft in Europe. In addition, Boeing has
redesigned the overwing exit door for its next-generation 737 series. This
redesigned, hinged door has pressurized springs so that it essentially pops
up and outward, out of the way, once its lever is pulled. The exit door
handle was also redesigned and tested to ensure that anyone could operate
the door using either single or double handgrips. Approximately 200 people
who were unfamiliar with the new design and had never operated an
overwing exit tested the outward-opening exit door. These tests found that
the average adult could operate the door in an emergency. The design
eliminates the problem of where to stow the exit hatch because the door
moves up and out of the egress route.
While the new swing-out doors are available, it will take some time for
them to be widely used. Because of structural difficulties and cost, the new
doors are not being considered for the existing fleet. For new-production
airplanes, their use is mixed because JAA requires them in Europe for some
newer Boeing 737s, but FAA does not require them in the United States.
However, FAA will allow their use. As a result, some airlines are including
the new doors on their new aircraft, while others are not. For example,
Southwest Airlines has the new doors on its Boeing 737s. The extent to
which other airlines and aircraft models will have the new doors installed
remains to be seen and will likely depend on the cost of installation, the
European market for the aircraft, and any additional costs to train flight
attendants in its use.
6
NTSB, Emergency Evacuation of Commercial Airplanes, [A-00-76] (Washington, D.C.,
2000).
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Next Generation
Evacuation Equipment
and Procedures
Background
Airbus, a leading aircraft manufacturer, has begun building a family of A380
aircraft, also called Large Transport Aircraft (see fig. 16). Early versions of
the A380, which is scheduled to begin flight tests in 2005 and enter
commercial service in 2006, will have 482 to 524 seats. The A380-800
standard layout references 555 seats. Later larger configurations could
accommodate up to 850 passengers. The A380 is designed to have 16
emergency doors and require 16 escape slides, compared with the 747,
which requires 12. Later models of the A380 could have 18 emergency exits
and escape slides.
Figure 16: Airbus’ Planned Double Deck Aircraft
Status
The advent of this type of Large Transport Aircraft is raising questions
about how passengers will exit the aircraft in an emergency. The upper
deck doorsill of the A380 will be approximately 30 feet above the ground,
depending on the position (attitude) of the aircraft. According to an Airbus
official responsible for exit slide design and operations, evacuation slides
have to reach the ground at a safe angle even if the aircraft is tipped up;
however, extra slide length is undesirable if the sill height is normal.
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Previously, regulations would have required slides only to touch the ground
in the tip-up case, even if that meant introduction of relatively steep sliding
surfaces. However, because of the sill height, passengers may hesitate
before jumping and their hesitation may extend the total evacuation time.
Because some passengers may be reluctant to leap onto the slide when
they can see how far it is to the ground, the design concept of the A380
evacuation slides includes blinder walls at the exit and a curve in the slide
to mask the distance to the ground.
A next-generation evacuation system developed by Airbus and Goodrich
called the “intelligent slide” is a possible solution to the problem of the
Large Transport Aircraft’s slide length. The technology is not a part of the
slide, but is connected to the slide through what is called a door
management system composed of sensors. The “brains” of the technology
will be located inside the forward exit door of the cabin, and the
technology is designed to adjust the length of the slide according to the
fuselage’s tipping angle to the ground. The longest upper-deck slide for an
A380 could exceed 50 feet.
The A380 slides are made of a nylon-based fabric that is coated with
urethane or neoprene, and they are 10 percent lighter than most other
slides on the market. They have to be packed tightly into small bundles at
the foot of emergency exit doors and are required to be fully inflated in 6
seconds. Officials at Airbus noted that the slides are designed to withstand
the radiant heat of a postimpact fire for 180 seconds, compared with the 90
seconds required by regulators.
According to a Goodrich official, FAA will require Goodrich to conduct
between 2,000 and 2,500 tests on the A380 slides to make sure they can
accommodate a large number of passengers quickly and withstand wind,
rain, and other weather conditions. The upper-level slides, which are wide
enough for two people, have to enable the evacuation of 140 people per
minute, according to Airbus officials. An issue to be resolved is whether a
full-scale demonstration test will be required or whether a partial test using
a certain number of passengers, supplemented by a computer simulation of
an evacuation of 555 passengers, can effectively demonstrate an
evacuation from this type of aircraft. Airbus officials told us that a full-scale
demonstration could result in undesirable injuries to the participants and is
therefore not the preferred choice.
Officials at the Association of Flight Attendants have expressed concern
that there has not been a full-scale evacuation demonstration involving the
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A380. They are concerned that computer modeling might not really match
the human experience of jumping onto a slide from that height. In addition,
they are concerned that other systems involved in emergency exiting, such
as the communication systems, need to be tested under controlled
conditions. As a result, they believe a full-scale demonstration under the
current 90-second standard is necessary.
Personal Flotation
Devices
Background
All commercial aircraft that fly over water more than 50 nautical miles from
the nearest shore are required to be equipped with flotation devices for
each occupant of the airplane. According to FAA, 44 of the 50 busiest U.S.
airports are located within 5 miles of a significant body of water. In
addition, life vests, seat cushions, life rafts, and exit slides may be used as
flotation devices for water emergencies.
FAA policies dictate that if personal flotation devices are installed beneath
the passenger seats of an aircraft, the devices must be easily retrievable.
Determinations of compliance with this requirement are based on the
judgment of FAA as the certifying authority.
Status
FAA is conducting research and testing on the location and types of
flotation devices used in aircraft. When it has completed this work, it is
likely to provide additional guidance to ensure that the devices are easily
retrievable and usable. FAA’s research is designed to analyze human
performance factors, such as how much time passengers need to retrieve
their vests, whether and how the cabin environment physically interferes
with their efforts, and how physically capable passengers are of reaching
their vests while seated and belted. FAA is reviewing four different life vest
installation methods and has conducted tests on 137 human subjects.
According to an early analysis of the data, certain physical installation
features significantly affect both the ability of a typical passenger to
retrieve an underseat life vest and the ease of retrieval. This work may lead
to additonal guidance on the location of personal flotation devices.
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FAA’s research may also indicate a need for additional guidance on the use
of personal flotation devices. In a 1998 report on ditching aircraft and water
survival, FAA found that airlines differed in their instructions to passengers
on how to use personal flotation devices.7 For example, some airlines
advise that passengers hold the cushions in front of their bodies, rest their
chins on the cushions, wrap their arms around the cushions with their
hands grasping the outside loops, and float vertically in the water. Other
airlines suggest that passengers lie forward on the cushions, grasp and hold
the loops beneath them, and float horizontally. FAA also reported that
airlines’ flight attendant training programs differed in their instructions on
how to don life vests and when to inflate them.
7
LB & M Associates, Inc., and Garnet A. McLean, Analysis of Ditching and Water Survival
Training Programs of Major Airframe Manufacturers and Airlines, CAMI [DOT/FAA/AM98/19], (Washington, D.C.).
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Appendix VII
Summaries of General Cabin Occupant Safety
and Health Advancements
This appendix presents information on the background and status of
potential advancements in general cabin occupant safety and health that
we identified, including the following:
• advanced warnings of turbulence;
• preparations for in-flight medical emergencies;
• reductions in health risks to passengers with certain medical conditions,
including deep vein thrombosis; and
• improved awareness of radiation exposure.
This appendix also discusses occupational safety and health standards for
the flight attendant workforce.
Advanced Warnings of
Turbulence
Background According to FAA, the leading cause of in-flight injuries for cabin
occupants is turbulence. In June 1995, following two serious events
involving turbulence, FAA issued a public advisory to airlines urging the
use of seat belts at all times when passengers are seated, but concluded
that the existing rules did not require strengthening. In May 2000, FAA
instituted a public awareness campaign, called Turbulence Happens, to
stress the importance of wearing safety belts to the flying public.
Because of the potential for injury from unexpected turbulence, ongoing
research is attempting to find ways to better identify areas of turbulence so
that pilots can take corrective action to avoid it. In addition, FAA’s July 2003
draft strategic plan targets a 33 percent reduction in the number of
turbulence injuries to cabin occupants by 2008—from an annual average of
15 injuries per year for fiscal years 2000 through 2002 to no more than 10
injuries per year.
Status
FAA is currently evaluating new airborne weather radar and other
technologies to improve the timeliness of warnings to passengers and flight
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attendants about impending turbulence. For example, the Turbulence
Product Development Team, within FAA’s Aviation Weather Research
Program, has developed a system to measure turbulence and downlink the
information in real time from commercial air carriers. The International
Civil Aviation Organization has approved this system as an international
standard. Ongoing research includes (1) detecting turbulence in flight and
reporting its intensity to augment pilots’ reports, (2) detecting turbulence
remotely from the ground or in the air using radar, (3) detecting turbulence
remotely using LIDAR1 or the Global Positioning System’s constellation of
satellites, and (4) forecasting the likelihood of turbulence over the
continental United States during the next 12 hours. Prototypes of the inflight detection system have been installed on 100 737-300s operated by
United Airlines, and two other domestic air carriers have expressed an
interest in using the prototype. FAA also plans to improve (1) training on
standard operating procedures to reduce injuries from turbulence, (2) the
dissemination of pilots’ reports of turbulence, and (3) the timeliness of
weather forecasts to identify turbulent areas. Furthermore, FAA
encourages and some airlines require passengers to keep their seatbelts
fastened when seated to help avoid injuries from unexpected turbulence.
Currently, pilots rely primarily on other pilots to report when and where
(e.g., specific altitudes and routes) they have encountered turbulent
conditions en route to their destinations; however, these reports do not
accurately identify the location, time, and intensity of the turbulence.
Further research and testing will be required to develop technology to
accurately identify turbulence and to make the technology affordable to the
airlines, which would ultimately bear the cost of upgrading their aircraft
fleets.
Preparations for Inflight Medical
Emergencies
1
LIDAR (LIght Detection And Ranging) is a technology that can measure the distance, speed,
rotation, and chemical composition and concentration of a remote target, such as
turbulence.
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Background
The Aviation Medical Assistance Act of 1998 directed FAA to determine
whether the current minimum requirements for air carriers’ emergency
medical equipment and crewmember emergency medical training should
be modified. In accordance with the act, FAA collected data for a year on
in-flight deaths and near deaths and concluded that enhancements to
medical kits and a requirement for airlines to carry automatic external
defibrillators were warranted. Specifically, the agency found that these
improvements would allow cabin crewmembers to deal with a broader
range of in-flight emergencies.
Status
On April 12, 2001, FAA issued a final rule requiring air carriers to equip
their aircraft with enhanced emergency medical kits and automatic
external defibrillators by May 12, 2004. Most U.S. airlines have installed this
equipment in advance of the deadline.
In the future, new larger aircraft may require additional improvements to
meet passengers’ medical needs. For example, new large transport aircraft,
such as the Airbus A-380, will have the capacity to carry about 555 people
on long-distance flights. Some aviation safety experts are concerned that
with the large number of passengers on these aircraft, the number of inflight medical emergencies will increase and additional precautions for inflight medical emergencies (e.g., dedicating an area for passengers who
experience medical emergencies in flight) should be considered. Airbus
has proposed a medical room in the cabin of its A-380 as an option for its
customers.
Reducing Health Risks
to Passengers with
Certain Medical
Conditions
Background
Passengers with certain medical conditions (e.g., heart and lung diseases)
can be at higher risk of health-related complications from air travel than
the general population. For example, passengers who have limited heart or
lung function or have recently had surgery or a leg injury can be at greater
risk of developing a condition known as deep vein thrombosis (DVT) or
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travelers’ thrombosis, in which blood clots can develop in the deep veins of
the legs from extended periods of inactivity. Air travel has not been linked
definitively to the development of DVT, but remaining seated for extended
periods of time, whether in one’s home or on a long-distance flight, can
cause blood to pool in the legs and increase the chances of developing DVT.
In a small percentage of cases, the clots can break free and travel to the
lungs, with fatal results.
In addition, the reduced levels of oxygen available to passengers in-flight
can have detrimental health effects on passengers with heart, circulatory,
and respiratory disorders because lower levels of oxygen in the air produce
lower levels of oxygen in the body—a condition known as hypoxia.
Furthermore, changes in cabin pressure (primarily when the aircraft
ascends and descends) can negatively affect ear, nose, and throat
conditions and pose problems for those flying after certain types of surgery
(e.g., abdominal, cardiac, and eye surgery).
Status Information on the potential effects of air travel on passengers with certain
medical conditions is available; however, additional research, such as on
the potential relationship between DVT and air travel, is ongoing. The
National Research Council, in a 2001 report on airliner cabin air quality,
recommended, among other things, that FAA increase efforts to provide
information on health issues related to air travel to crewmembers,
passengers, and health professionals. According to FAA’s Federal Air
Surgeon, since this recommendation was received, the agency has
redoubled its efforts to make information and recommendations on air
travel and medical issues available through its Web site
www.cami.jccbi.gov/aam-400/PassengerHandS.htm. This site also includes
links to the Web sites of other organizations with safety and health
information for air travelers, such as the Aerospace Medical Association,
the American Family Physician (Medical Advice for Commercial Air
Travelers), and the Sinus Care Center (Ears, Altitude, and Airplane Travel),
and videos on safety and health issues for pilots and air travelers. The
Aerospace Medical Association’s Web site,
http://www.asma.org/publication.html, includes guidance for physicians to
use in advising passengers about the potential risks of flying based on their
medical conditions, as well as information for passengers to use in
determining whether air travel is advisable given their medical conditions.
Furthermore, some airlines currently encourage passengers to do exercises
while seated, to get up and walk around during long flights, or to do both to
improve blood circulation; however, walking around the airplane can also
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put passengers at risk of injuries from unexpected turbulence. In addition,
a prototype of a seat has been designed with imbedded sensors, which
record the movement of a passenger and send this information to the cabin
crew for monitoring. The crew would then be able to track passengers
seated for a long time and could suggest that these passengers exercise in
their seats or walk in the cabin aisles to enhance circulation.
While FAA’s Web site on passenger and pilot safety and health provides
links to related Web sites and videos (e.g., cabin occupant safety and health
issues), historically, the agency has not tracked who uses its Web site or
how frequently it is used to monitor the traveling public’s awareness and
use of this site. Agency officials told us that they plan to install a counter
capability on its Civil Aerospace Medical Institute Web site by the end of
August 2003 to track the number of visits to its aircrew and passenger
health and safety Web site. The World Health Organization has initiated a
study to help determine if a linkage exists between DVT and air travel.
Further, FAA developed a brochure on DVT that has been distributed to
aviation medical examiners and cited in the Federal Air Surgeon’s Bulletin.
The brochure is aimed at passengers rather than airlines and suggests
exercises that can be done to promote circulation.
Improved Awareness
of Radiation Exposure
Background
Pilots, flight attendants, and passengers who fly frequently are exposed to
cosmic radiation at higher levels (on a cumulative basis) than the average
airline passenger and the general public living at or near sea level. This is
because they routinely fly at high altitudes, which places them closer to
outer space, which is the primary source of this radiation. High levels of
radiation have been linked to an increased risk of cancer and potential
harm to fetuses. The amount of radiation that flight attendants and frequent
fliers are exposed to—referred to as the dose—depends on four primary
factors: (1) the amount of time spent in flight; (2) the latitude of the flight—
exposure increases at higher latitudes; for example, at the same altitude,
radiation levels at the poles are about twice those at the equator; (3) the
altitude of the flight—exposure is greater at high altitudes because the
layer of protective atmosphere becomes thinner; and (4) solar activity—
exposure is higher when solar activity increases, as it does every 11 years
or so. Peak periods of solar activity, which can increase exposure to
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radiation by 10 to 20 times, are sometimes called solar storms or solar
flares.
Status
FAA’s Web site currently makes available guidance on radiation exposure
levels and risks for flight and cabin crewmembers, as well as a system for
calculating radiation doses from flying specific routes and specific
altitudes. To increase crewmembers’ awareness of in-flight radiation
exposure, FAA issued two Advisory Circulars for crewmembers. The first
Advisory Circular, issued in 1990, provided information on (1) cosmic
radiation and air shipments of radioactive material as sources of radiation
exposure during air travel; (2) guidelines for exposure to radiation; (3)
estimates of the amounts of radiation received on air carriers’ flights on
various routes to and from, or within, the contiguous United States; and (4)
examples of calculations for estimating health risks from exposure to
radiation. The second Advisory Circular, issued in 1994, recommended
training for crewmembers to inform them about in-flight radiation
exposure and known associated health risks and to assist them in making
informed decisions about their work on commercial air carriers. The
circular provided a possible outline of courses, but left it to air carriers to
gather the subject matter materials. To facilitate the monitoring of radiation
exposure levels by airliner crewmembers and the public (e.g., frequent
fliers), FAA has developed a computer model, which is publicly available
via the agency’s Web site. This Web site also provides guidance and
recommendations on limiting radiation exposure. However, it is unclear to
what extent flight attendants, flight crews, and frequent fliers are aware of
and use FAA’s Web site to track the radiation exposure levels they accrue
from flying. Agency officials told us that they plan to install a counter
capability its Civil Aerospace Medical Institute Web site by the end of
August 2003, to track the number of visits to its aircrew and passenger
health and safety Web site. FAA also plans to issue an Advisory Circular by
early next year, which incorporates the findings of a just completed FAA
report, “What Aircrews Should Know About Their Occupational Exposure
to Ionizing Radiation.” This Advisory Circular will include recommended
actions for aircrew and information on solar flare event notification of
aircrew. While FAA provides guidance and recommendations on limiting
the levels of cosmic radiation that flight attendants and pilots are exposed
to, it has not developed any regulations.
In contrast, the European Union issued a directive for workers in May 1996,
including air carrier crewmembers (cabin and flight crews) and the general
public, on basic safety and health protections against dangers arising from
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ionizing radiation. This directive set dose limits and required air carriers to
(1) assess and monitor the exposure of all crewmembers to avoid
exceeding exposure limits, (2) work with those individuals at risk of high
exposure levels to adjust their work or flight schedules to reduce those
levels, and (3) inform crewmembers of the health risks that their work
involves from exposure to radiation. It also required airlines to work with
female crewmembers, when they announce a pregnancy, to avoid exposing
the fetus to harmful levels of radiation. This directive was binding for all
European Union member states and became effective in May 2000.
According to European safety officials, pregnant crewmembers are often
given the option of an alternative job with the airline on the ground to avoid
radiation exposure to their fetuses. Furthermore, when flight attendants
and pilots reach recommended exposure limits, European air carriers work
with crewmembers to limits or change their subsequent flights and
destinations to minimize exposure levels for the balance of the year. Some
air carriers ground crewmembers when they reach annual exposure limits
or change their subsequent flights and destinations to minimize exposure
levels for the balance of the year.
Occupational Safety
and Health Standards
for Flight Attendants
Background
In 1975, FAA assumed responsibility from the Occupational Health and
Safety Administration (OSHA) for establishing safety and health standards
for flight attendants. However, FAA has only recently begun to take action
to provide this workforce with OSHA-like protections. For example, in
August 2000, FAA and OSHA entered into a memorandum of understanding
and issued a joint report in December 2000, which identified safety and
health concerns for the flight attendant workforce and the extent to which
OSHA-type standards could be used without compromising aviation safety.
On September 29, 2001, the DOT Office of the Inspector General (DOT IG)
reported that FAA had made little progress toward providing flight
attendants with workplace protections and urged FAA to address the
recommendations in the December 2000 report and move forward with
setting safety and health standards for the flight attendant workforce. In
April 2002, the DOT IG reported that FAA and OSHA had made no progress
since it issued its report in September 2001. According to FAA officials, the
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joint FAA and OSHA effort was put on hold because of other priorities that
arose in response to the events of September 11, 2001.
Status
FAA has not yet established occupational safety and health standards to
protect the flight attendant workforce. FAA is conducting research and
collecting data on flight attendants’ injuries and illnesses.
On March 4, 2003, FAA announced the creation of a voluntary program for
air carriers, called the Aviation Safety and Health Partnership Program.
Through this program, the agency intends to enter into partnership
agreements with participating air carriers, which will, at a minimum, make
data on their employees’ injuries and illnesses available to FAA for
collection and analysis. FAA will then establish an Aviation Safety and
Health Program Aviation Rule-Making Committee to provide advice and
recommendations to
• develop the scope and core elements of the partnership program
agreement;
• review and analyze the data on employees’ injuries and illnesses;
• identify the scope and extent of systematic trends in employees’ injuries
and illnesses;
• recommend remedies to FAA that use all current FAA protocols,
including rule-making activities if warranted, to abate hazards to
employees; and
• create any other advisory and oversight functions that FAA deems
necessary.
FAA plans to select members to provide a balance of viewpoints, interests,
and expertise. The program preserves FAA’s complete and exclusive
responsibility for determining whether proposed abatements of safety and
health hazards would compromise or negatively affect aviation safety.
FAA is also funding research through the National Institute for
Occupational Safety and Health (NIOSH) to, among other things, determine
the effects of flying on the reproductive health of flight attendants, much of
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Summaries of General Cabin Occupant Safety and Health Advancements
which has been completed.2 FAA plans to monitor cabin air quality on a
selected number of flights, which will help it set standards for the flight
attendant workforce.
The Association of Flight Attendants has collected a large body of data on
flight attendants’ injuries and illnesses, which it considers sufficient for use
in establishing safety and health standards for its workforce. Officials from
the association do not believe that FAA needs to collect additional data
before starting the standard-setting process.
The European Union has occupational safety and health standards in place
to protect flight attendants, including standards for monitoring their levels
of radiation exposure. An official from an international association of flight
attendants told us that while flight attendants in Europe have concerns
similar to those of flight attendants in the United States (e.g., concerns
about air quality in airliner cabins), the European Union places a heavier
emphasis on worker safety and health, including safety and health
protections for flight attendants.
2
NIOSH is also conducting research on airliner cabin environmental quality, respiratory
symptoms of flight attendants, and disease transmission.
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Appendix VIII
Application of a Cost Analysis Methodology to
Inflatable Lap Belts
The following illustrates how a cost analysis might be conducted on each of
the potential advancements discussed in this report. Costs estimated
through this analysis could then be weighed against the potential lives
saved and injuries avoided from implementing the advancements. This
methodology would allow advancements to be compared using comparable
cost data that when combined with similar analyses of effectiveness to help
decisionmakers determine which advancements would be most effective in
saving lives and avoiding injuries, taking into account their costs. The
methodology provides for developing a cost estimate despite significant
uncertainties by making use of historical data (e.g, historical variations in
fuel prices) and best engineering judgments (e.g., how much weight an
advancement will add and how much it will cost to install, operate, and
maintain). The methodology formally takes into account the major sources
of uncertainty and from that information develops a range of cost
estimates, including a most likely cost estimate. Through a common
approach for analyzing costs, the methodology facilitates the development
of comparable estimates. This methodology can be applied to
advancements in various stages of development.
Inflatable Lap Belts
Inflatable lap belts are designed to protect passengers from a fatal impact
with the interior of the airplane, the most common cause of death in
survivable accidents. Inflatable seat belts adapt advanced automobile
technology to airplane seats in the form of seat belts with air bags
embedded in them. Several hundred of these seatbelt airbags have been
installed in commercial airliners in bulkhead rows.
Summary of Results
We calculated that requiring these belts on an average-sized airplane in the
U.S. passenger fleet would be likely to cost from $98,000 to $198,000 and to
average about $140,000 over the life of the airplane. On an annual basis, the
cost would be likely to range from $8,000 to $17,000 and to average $12,000.
We considered several factors to explain this range of possible costs. The
installation price of these belts is subject to uncertainty because of their
limited production to date. In addition, these belts add weight to an
aircraft, resulting in additional fuel costs. Fuel costs depend on the price of
jet fuel and on how many hours the average airplane operates, both subject
to uncertainty. Table 5 lists the results of our cost analysis for an averagesized airplane in the U.S. fleet.
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Appendix VIII
Application of a Cost Analysis Methodology to Inflatable Lap Belts
Table 4: Costs to Equip an Average-sized Airplane in the U.S. Fleet with Inflatable
Lap Seat Belts, Estimated under Alternative Scenarios (In 2002 discounted dollars)
Cost scenario
Low
Average
High
95 percentilea
$98,000
$140,000
$198,000
$186,000
$8,000
$12,000
$17,000
$16,000
$0.08
$0.13
$0.19
$0.18
Cost
Life-cycle
Annualized
Per ticket
b
Source: GAO analysis.
a
For example, a 95 percentile estimate means that there is a 95 percent probability that the total lifecycle costs per airplane will be $186,000 or less.
b
Cost rounded to the nearest cent.
According to our analysis, the life-cycle and annualized cost estimates in
table 5 are influenced most by variations in jet fuel prices, followed by the
average number of hours flown per year and the installation price of the
belts. The cost per ticket is influenced most by variations in jet fuel prices,
followed by the average number of hours flown per year, the number of
aircraft in the U.S. fleet, and the number of passenger tickets issued.
Methodology
To analyze the cost of inflatable lap belts, we collected data on key cost
variables from a variety of sources. Information on the belts’ installation
price, annual maintenance and refurbishment costs, and added weight was
obtained from belt manufacturers. Historical information on jet fuel prices,
extra gallons of jet fuel consumed by a heavier airplane, average hours
flown per year, average number of seats per airplane, number of airplanes
in the U.S. fleet, and number of passenger tickets issued per year was
obtained from FAA and DOT’s Office of Aviation Statistics.
To account for variation in the values of these cost variables, we performed
a Monte Carlo simulation.1 In this simulation, values were randomly drawn
10,000 times from probability distributions characterizing possible values
1
“Monte Carlo simulation is a widely used computational method for generating probability
distributions of variables that depend on other variables or parameters represented as
probability distributions. Monte Carlo methods are to be contrasted with the deterministic
methods used to generate specific single number or point estimates.” Susan Poulter, “Monte
Carlo Simulation in Environmental Risk Assessment - Science, Policy And Legal Issues,” 9
Risk: Health, Safety & Environment 7 [Winter 1998].
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Appendix VIII
Application of a Cost Analysis Methodology to Inflatable Lap Belts
for the number of seat belts per airplane, seat belt installation price, jet fuel
price, number of passenger tickets, number of airplanes, and hours flown.2
This simulation resulted in forecasts of the life-cycle cost per airplane, the
annualized cost per airplane, and the cost per ticket.
Major assumptions in the cost analysis are described by probability
distributions selected for these cost variables. For jet fuel prices, average
number of hours flown per year, and average number of seats per airplane,
historical data were matched against possible probability distributions.3
Mathematical tests were performed to find the best fit between each
probability distribution and the data set’s distribution. For the installation
price, number of passenger tickets, and number of airplanes, less
information was available.4 For these variables, we selected probability
distributions that are widely used by researchers. Table 6 lists the type of
probability distribution and the relevant parameters of each distribution for
the cost variables.
Table 5: Key Assumptions
Cost variable
Type of
distribution
Mean or
average
Standard
deviation
Fuel price
Seats
lognormal
$0.93
$0.33
lognormal
161
8
Installation price
triangular
Hours
extreme value
2,353
Airplanes
normal
4,438
399
Tickets
normal
419
35
Minimum
Maximum
Likeliest
$300
$600
$450
Mode
Scale
2,643
539
Source: GAO analysis.
2
A probability distribution is a set of all possible events and their associated probabilities.
Probability refers to the likelihood of an event.
3
Historical data from 1975 through 2001 were available for the number of seats per plane,
and from 1977 through 2002 for jet fuel prices. Aircraft utilization data for 2001 were
available for annual hours per aircraft.
4
Historical data from 1995 through 2001 were available for the number of planes and tickets.
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Appendix IX
GAO Contacts and Staff Acknowledgments
GAO Contacts
Gerald L. Dillingham (202) 512-2834
Glen Trochelman
(202) 512-2834
Beverly Norwood
(202) 512-2834
Staff Acknowledgments
In addition to those named above, Chuck Bausell, Helen Chung, Elizabeth
Eisenstadt, David Ehrlich, Bert Japikse, Sarah Lynch, Sara Ann
Moessbauer, and Anthony Patterson made key contributions to this report.
(540017)
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