TAWS Buyer's Guide

PILOT’S GUIDE
Terrain Awareness and
Warning Systems—TAWS
Buyer’s Guide
B Y
C
P A U L
See TAWS COMPARISONS CHART on pages 36, 37 & 39
N O V A C E K
ontrolled Flight Into Terrain
(CFIT) describes an accident where a completely
airworthy aircraft is flown into
the terrain. These accidents only
occur during poor visual conditions; but other factors besides
visibility usually contribute, such
as a cockpit distraction, malfunctioning equipment, an ATC error
or a pilot/controller miscommunication. To reduce the occurrence
of Controlled Flight Into Terrain
accidents, Terrain Awareness
and Warning Systems (TAWS)
were developed to provide a
warning of a possible terrain conflict. The purpose of a TAWS is
to provide a warning with enough
time for the flight crew to take
appropriate action.
There are various types of
TAWS systems, whether they fall
into the definition of TAWS or not.
The three general categories provide increasing levels of protection—from the basic Terrain Map
to TAWS-B through the highest
level of protection—TAWS-A.
Many moving maps contain
databases of terrain elevations
gained from government charts.
These “terrain depiction” systems
show the terrain in color codes
just as sectional charts. The colors depict elevations above sea
level and itʼs up to the pilot to
determine if sufficient clearance
exists. A little bit of mental gymnastics are required to correctly
interpret these moving maps.
The terrain mapping systems are
only capable of giving the pilot
the general awareness of the terrain, no audio or visual warnings
are given.
A true TAWS system on the
other hand, can look ahead of
the aircraft and warn the pilot
of impending impact with the
ground; thus monitoring the
pilotʼs actions and providing an
audible and visual alert if the aircraft is about to have a date with
the ground. Hopefully, the pilot
of a TAWS-equipped aircraft will
never hear a terrain or obstacle
warning, but the safety margins
are there just in case.
The TAWS computer receives
position information from a GPS
receiver, and compares that
position with the internal terrain or obstacle database. The
Federal Aviation Regulations Require:
TAWS Class-A equipment is required for turbine-powered airplanes operated
under part 121 (airline) and part 135 (charter) of 10 or more passenger seats.
TAWS Class-B equipment is required for turbine-powered airplanes operated
under part 91 with six or more passenger seats and for turbine-powered airplanes
operated under part 135 with six to nine passenger seats.
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TAWS computer also receives
aircraft configuration and air-data
information to then create a 4-D
position of latitude, longitude, altitude and time. It then compares
this position with the on-board
database of terrain, obstacles
and runways to determine any
conflicts. If the TAWS computer detects a possible conflict
between the future flight path
of the aircraft and terrain, visual
and audible warnings are given
to the pilot.
Class-A TAWS
For those airplanes that
require Class-A TAWS, the systems include a minimum of five
basic functions:
1. Forward looking terrain
avoidance
This function looks ahead and
below the aircraft flight path to
provide a suitable alert if a potential threat exists.
2. Premature descent alert
This function uses the predicted flight path information (determined from an approach navigation source) and its own airport
database to determine if the
aircraft is below the normal (typically 3 degree) approach path for
the nearest runway. If a conflict is
detected, a warning is given.
3. Attention alerts
The system provides appropriate visual and audio alerts for
both cautions and warnings.
4. Terrain awareness display
The TAWS equipment provides
terrain information to a suitable
display system—radar or multifunction display.
5. Indications of imminent
contact with the ground
The TAWS equipment provides
indications of possible terrain
conflicts for the following conditions:
• Excessive rates of descent
• Excessive closure rate to terrain
• Negative climb rate or altitude
loss after takeoff
• Flight into terrain when not in
landing configuration
• Excessive downward deviation
from an ILS glideslope
• Voice callout “five hundred,”
when the aircraft descends to
500 feet above the terrain or
nearest runway elevation
Class-B TAWS
For those aircraft that require
Class-B TAWS, the systems
include a minimum of four basic
functions:
1. Forward looking terrain
avoidance
This function looks ahead and
below the aircraft flight path to
provide a suitable alert if a potential threat exists.
2. Premature descent alert
This function uses the predicted flight path information
(determined from an approach
navigation source) and its own
airport database to determine if
the aircraft is below the normal
(typically 3 degree) approach
path for the nearest runway. If a
conflict is detected, a warning is
given to the pilot.
3. Attention alerts
The system provides appropriate visual and audio alerts for
both cautions and warnings.
4. Indications of imminent
contact with the ground
The TAWS equipment provides
indications of possible terrain
conflicts for the following conditions:
• Excessive rates of descent
• Negative climb rate or altitude loss after takeoff
• Voice callout “five hundred”
when the aircraft descends to
500 feet above the terrain or
nearest runway elevation
NOTE: A Class-B TAWS installation does not require a terrain
display (as does Class-A), but
the awareness of terrain around
the aircraft is severely lacking.
The TAWS equipment is either
contained in a remote avionics
box that feeds a multi-function
display, or contained entirely in
the display unit. The larger aircraft generally use the remote
box configuration, while the
smaller aircraft use combined
units. The following are short
descriptions of each TAWS manufacturer. The comparison chart
that accompanies this article lists
the particulars of each TAWS
unit.
Honeywell
Honeywellʼs EGPWS, or
Enhanced Ground Proximity
Warning System, was the pioneer TAWS system that combined an exhaustive terrain and
obstacle database with the traditional Ground-Prox systems to
offer look-ahead alerting. There
are 10 EGPWS systems currently available from Honeywell
that can be installed as remote
computers in over 250 types of
aircraft. Since the EGPWS was
first introduced, 30,000 have
been installed in aircraft ranging
in size from small general avia- 35 -
tion airplanes to the largest air
transports. They even have two
models specifically designed for
the special needs of helicopters,
who routinely fly eye-level with
the obstacles theyʼre trying to
avoid.
The TAWS-A Mark series
(Mark V-VIII) of EGPWS are
intended for corporate jet and
air transport installations. As an
option, they contain software
to detect windshear conditions
and alert the flight crew when
to take evasive maneuvers to
escape a microburst. A recent
addition to the Mark series is
the software upgrade for RAAS,
Honeywellʼs Runway Awareness
and Advisory System. The fieldupdatable software enhancement
uses GPS position data and the
EGPWS database to provide
audio advisories that supplement
flight crew awareness of position
during ground operations and on
approach to landing. Honeywell
is the only TAWS manufacturer
offering this enhanced safety
feature.
The Mark XXI (TAWS-B) and
Mark XXII (TAWS-A) offer terrain awareness functions tailored
uniquely to helicopter flight profiles. For the light jet, turboprop
and piston crowd, Honeywellʼs
general aviation line of EGPWS
offer TAWS-B awareness and
alerting of potential terrain or
obstacles. The EGPWS is even
bundled with traffic alerting sensors, either TAS or TCAS-I,
to provide total awareness of
ground-based and air-based
threats.
Even though the mandated
TAWS-B installations donʼt
require a cockpit display, the
graphic depiction of terrain surrounding the aircraft greatly
Continued on page 38…
TAWS COMPARISONS
TAWS REMOTE COMPUTERS
Model
Description
Price
Honeywell www.egpws.com, www.bendixking.com
EGPWS –
Mark V
TAWS-A, w/windshear detection, vertical situation
display (VSD), radar AutoTilt T, worldwide Terrain/Obstacle/Airport database, optional RAAS.
Remote Computer - Digital Interface
$74,710 without internal GPS
$77,630 w/internal GPS
RAAS add $18,932
EGPWS –
Mark VII
TAWS-A, w/windshear detection, vertical situation
display (VSD), radar AutoTilt T, worldwide database,
optional RAAS. Remote Computer - Analog Interface
$74,710 without internal GPS
$77,630 w/internal GPS
RAAS add $18,932
EGPWS–
Mark VI
TAWS-A, regional Terrain/Obstacle/Airport databases.
Remote Computer designed for Turboprop aircraft
- Limited Analog/Digital Interfaces
$26,168 without internal GPS
$28,358 w/internal GPS
EGPWS –
Mark VIII
TAWS-A, worldwide Terrain/Obstacle/Airport database.
Remote Computer designed for Turbofan and Turboprop aircraft - Limited Analog/Digital Interfaces
$39,358 without internal GPS
$40,402 w/internal GPS
EGPWS –
Mark XXI
Helicopter
TAWS-A, w/internal GPS, regional Terrain/Obstacle/
Airport/Oil Rig databases. Remote Computer - All
Displays
$41,614
KGP-560
EGPWS
TAWS-B, w/internal GPS, regional Terrain/
Obstacle/Airport databases. Remote Computer Limited Displays
$10,090
KGP-860
EGPWS
TAWS-B, w/internal GPS, enhanced alerting, regional
Terrain/Obstacle/Airport
databases. Remote Computer - All Displays
$13,090
EGPWS Mark XXI
Helicopter
TAWS-B, w/internal GPS, regional Terrain/
Obstacle/Airport databases. Remote Computer - All
Displays
$12,900
KMH-880
TAWS-B & TAS (traffic). Remote TAWS
Computer / Traffic Sensor
$29,990 Includes Install kit
and antenna
KMH-980
TAWS-B & TCAS-I (traffic). Remote TAWS
Computer / Traffic Sensor
$38,280 Includes Install kit
and antenna
L-3 Avionics Systems www.as.l-3com.com/products/taws.asp
LandMark 8000
LandMark 8100
TAWS-B, worldwide database. Remote Computer
TAWS-B w/internal WAAS-GPS, worldwide
database, enhanced positioning. Remote Computer
$11,550
$13,925
Universal Avionics www.universalavionics.com
TAWS-A
TAWS-A. Remote Computer
$36,500
TAWS-B
TAWS-B. Remote Computer
$22,000
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TAWS REMOTE COMPUTERS continued…
Model
Description
Price
ACSS (L-3/Thales) www.acssonboard.com/
TW-950/951
TAWS+
TAWS-A, optional GPS. Remote Computer
$77,500 no/GPS
$89,250 w/GPS
TT-950/951/
952
TAWS-A with TCAS II, windshear, optional GPS.
Remote TAWS Computer / Traffic Sensor
TT 950/951 - $217,385
TT 952 (w/GPS) - $230,135
TERRAIN DISPLAYS
Model
Description
Price
Skymap IIIC
Rudimentary Terrain Moving Map—
Panel or pedestal-mount
$2,470
KMD-150
Terrain Map - Combination moving map display with
GPS navigation
$3,870 no/GPS
$4,570 w/GPS
KMD-250
Terrain Map with Relative Elevation mode.
$4,140 no/GPS
Combination moving map display with GPS navigation,
$4,630 w/GPS
traffic & weather
KMD-550
Display only for Honeywell EGPWS. MultiFunction Display – TAWS, Traffic, Datalink
& Stormscope
Additional circuit board to interface with EGPWS - $2,100
KMD-850
Display only for Honeywell EGPWS. MultiFunction Display – TAWS, Traffic, Datalink, Stormscope & Radar
Additional circuit board to interface with EGPWS - $2,100
MFRD
Primarily Radar Indicator. Display for any
Honeywell EGPWS. Multi-Function Display—
radar, TAWS, traffic, FMS & checklist
$42,590
TRA-45
Radio Altitude and EGPWS. Display for any Honeywell
EGPWS. Replaces existing 3 inch Radio Altimeter
$14,500
Dedicated page for EGPWS display. MultiFunction Display—TAWS, Traffic, Datalink, Stormscope & Radar
Additional software to interface with EGPWS - $2000
Dedicated page for EGPWS display. MultiFlightMax EX5000 Function Display – TAWS, Traffic, Datalink, Stormscope & Radar
Additional software to interface with EGPWS - $2000
Honeywell www.bendixking.com
Avidyne www.avidyne.com
FlightMax EX500
All prices are subject to change. Please contact the individual manufacturer or authorized dealer for current pricing.
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TAWS BUYER'S GUIDE
Continued from page 35
enhances the pilotʼs ability to
plan escape maneuvers when
a turn may be more appropriate
than just a pull-up. Honeywell
offers many options to display
TAWS, as well as offering a few
moving-map displays that just
depict a colored terrain map.
L-3 Avionics Systems
L-3 Communications recently
bought the entire BFGoodrich
line of avionics, including the
Stormscope and LandMark
TAWS products. The LandMark
8000 and 8100 are Class-B
TAWS remote-mounted units
that display terrain information
on a variety of Multi-Function
Displays. The LandMark 8100
is the first stand-alone Class-B
TAWS to offer an optional WAASGPS sensor. Thus eliminating
the need for multiple inputs from
other aircraft sensors, and simplifying the installation process.
By operating autonomously, the
LandMark 8100 provides terrain
data without complicated GPS,
air-data or temperature inputs. In
addition, the LandMark system
offers greater terrain resolution,
providing an accurate lay of the
land with crisper imaging, and
more distinct runway and obstacle depictions. Whether depicting terrain on an MFD, EFIS or
Radar Indicator, the LandMark
TAWS easily integrates with
existing cockpits.
Universal Avionics
Universal Avionics is generally
known for their excellent FMS
line, and just recently received
approval for their TAWS Class-A
and Class-B remote-mounted
units. Their system is unique in
that besides displaying the terrain in a plan view (looking down
or “Godʼs eye” view) it can also
display a complete profile (side
view) of the terrain in relation
to the entire flight plan, even
before the aircraft is airborne.
It differs from EGPWS in that it
uses inputs from an FMS to project an aircraftʼs flight path onto
the terrain display. The resulting unprecedented “look-ahead”
capability can provide warnings
and alerts well in advance of
potential hazards, allowing time
for the pilot to make the necessary maneuvers or waypoint corrections for terrain avoidance.
If that isnʼt enough, the
Universal system also depicts
a 3-D perspective view on
video-capable devices such as
Universalʼs Flat Panel Integrated
Display, FMS Display Control
Unit and Cockpit Display. On the
display, a blinking star-shaped
symbol shows the position of the
hazard based on the aircraftʼs
predicted flight path. This graphic
is colored white, yellow or red
corresponding to Advisory,
Caution and Warning alert levels
respectively.
ACSS
The TAWS+ Terrain Awareness
Warning System from ACSS
brings advanced terrain prediction and avoidance technology to
the cockpit with their capable line
of remote-mount units. TAWS+
has the patented Terrain Advisory
Line (TAL), “Avoid Terrain” and
Engine Out features. These
advanced functions encompass
terrain and airport databases.
Available with standard aircraft
climb rate, TAWS+ offers a
unique set of enhanced features
in a line-replaceable unit (LRU).
An optional GPS card can be
installed in the same unit, providing even greater situational
awareness capability. Building
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on the TAWS+ capabilities, the
TAWS+Performance package
is a step beyond conventional
TAWS offering the higher level of
safety afforded by basing alerts
on the actual ability to climb.
Sophisticated modeling of aircraft climb capabilities provides
the most complete picture for
improved situational awareness.
In addition to audio and
visual alerts, TAWS+ provides
enhanced situational awareness
with the unique Terrain Advisory
Line (TAL) feature. Extending the
conventional TAWS cautionary
terrain segment, the TAL reaches
out to 30 degrees on either side
of the aircraft flight path and out
as far as two minutes in front of
the aircraft, providing the crew
with an enhanced indication of
potential hazards in the current
flight path. ACSS can supply the
TAWS+ or TAWS+Performance
capability in a single remotemounted box or combined with a
TCAS-II traffic sensor. The combined T2CAS is a form fit for the
TCAS-2000 remote sensor and
adds TAWS capability without the
addition of a second box.
Avidyne
Avidyne offers two multifunction displays that interface
to any Honeywell EGPWS,
either Class-A or Class-B. Their
FlightMax EX-500 is a six-inch
display intended to be mounted
within the existing radio rack of
small aircraft or in place of the
radar display in larger aircraft.
The multi-function display (MFD)
comes standard with a database
of terrain elevations, obstacles
and waterways, which then
requires the pilot to interpret
any terrain threats. The addition
of a remote-mounted EGPWS
computer provides full TAWS
Continued on page 40…
TERRAIN DISPLAYS continued…
Model
Description
Price
GNS-400
TAWS-like, Terrain Map. GPS Navigator
Software & hardware
(factory) upgrade—$500
GNS-420
TAWS-like, Terrain Map.
GPS Navigator / Moving Map
Software & hardware
(factory) upgrade—$500
GNS-430
TAWS-like, Terrain Map.
GPS Navigator / Moving Map / Nav/Com
Software & hardware
(factory) upgrade—$500
GNS-500
TAWS-B. GPS Navigator / Moving Map
Software & hardware
(factory) upgrade—$8,000
GNS 530
TAWS-B. GPS Navigator / Moving Map /
Nav/Com
Software & hardware
(factory) upgrade—$8,000
MX20
MFD moving map with optional traffic and
weather interface capability,
radar and TAWS-B
$7,295
w/ I/O Traffic: $8,495
w/ I/O Traffic & Radar
(TAWS-B): $14,495
Garmin www.garmin.com
Chelton www.cheltonflightsystems.com
TAWS-A, B or C. Complete PFD/MFD EFIS with
FlightLogic EFIS Synthetic Vision, TAWS-C included TAWS-B or A
optional
TAWS-C – included
TAWS-B – additional
$10,000
TAWS-A – additional
$25,000
Sandel www.sandel.com
ST3400
TAWS and RMI. TAWS-A or B. TAWS Computer
and Display – can replace existing 3 inch RMI
TAWS-A – $34,500
TAWS-B – $20,950
Aspen Avionics www.aspenavionics.com
AT-300
TAWS & Vertical Speed Indicator. Terrain Map.
Combination moving map display with GPS
navigation – can replace existing 3 inch VSI
(certification mid-2005)
$3,995 – certified
$3,495 – non certified
PANEL-MOUNTED SWITCH / ANNUNCIATOR UNITS
Model
Description
Price
Mid-Continent Instruments www.mcico.com
MD-41
Terrain Awareness Control Unit. Panel-mounted,
Mode Switch and Alert Lights
All prices are subject to change. Please contact the individual manufacturer or authorized dealer for current pricing.
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$984 - $1,140
TAWS BUYER'S GUIDE
Continued from page 38
capability including visual and
audible alerting. If the EGPWS
detects a terrain conflict, a message is posted that directs the
pilot to access the TAWS page,
but the audio callout and remote
annunciators are always active.
Avidyneʼs bigger brother MFD,
the FlightMax EX-5000, is 10
inches wide and part of the
Entegra system being installed
in many factory aircraft (Cirrus,
Lancair, Piper, etc.), although it
is also available for retrofit into
existing aircraft.
Garmin
Garmin offers three options
of terrain awareness, software
upgrades for their popular GNS430 and 530, and a terrain
display with their MX20 moving
map display. Customers of existing GNS-530s or GPS-500s can
have the units upgraded by the
Garmin factory for TAWS ClassB capability for $8,000, which
doesnʼt include the aircraft modifications necessary for remote
warning annunciators or audio
interface. This is most likely the
easiest upgrade path for the
FAA TAWS-B mandate in those
aircraft that already have the
GNS-530, although a separate
and continuous display of terrain
(MFD) is much better when flying
in mountainous terrain.
For those aircraft that have
the Garmin 400 series navigators (400, 420 & 430) a TAWSlike software field upgrade is
available for $500. The addition
enables the depiction of surrounding terrain and obstacles
in bright yellow and red, relative
to the current altitude, but is not
certified for full TAWS-B capability and does not satisfy the FAA
TAWS mandate.
Garmin purchased the entire
line of avionics from UPS
Aviation Technologies, including the MX20 moving map. This
fully-capable moving map/MFD
comes standard with a database
of terrain elevations and obstacles displayed in much the same
manner as a sectional chart. It
is not a true TAWS and therefore does not qualify for the FAA
TAWS mandate, but it does offer
a unique relative terrain mode
that color codes any terrain near
the aircraft altitude. As an option,
the MX20 can interface to the
Honeywell or LandMark Class-B
TAWS computers.
Chelton
The FlightLogic Synthetic
Vision EFIS is a complete flight/
navigation instrumentation system that provides information to
a pilot via computer-generated
screen displays on panel-mounted hardware. The hardware is
comprised of a high-brightness
LCD screen, menu buttons, control knob and slip indicator, all of
which are backlit. The FlightLogic
EFIS system uses terrain, airport
and runway databases to warn
of hazardous terrain within the
search envelope in front of the
aircraft. The FlightLogic system
comes standard with a Class-C
TAWS, which may be upgraded
to Class-B or Class-A TAWS. A
unique feature of the FlightLogic
Primary Flight Display (PFD) is
a color-coded, wireframe, 3-D
Synthetic Vision display that
depicts terrain ahead of the aircraft.
Sandel
The Sandel ST-3400 TAWS/
RMI was the first self-contained
Class-A or Class-B TAWS system that includes an integrated
full-color, multi-screen, edge-to- 40 -
edge display with a built-in RMI
function. The ST-3400 is a selfcontained TAWS that replaces
an existing RMI, therefore saving
substantial costs because new
panels do not need to be fabricated. Sandelʼs patented edgeto-edge display technology provides a large viewing area equal
in size to a 4 inch display.
Aspen Avionics
The AT-300 display combines
moving terrain mapping functions with GPS navigation depictions. This 3 inches display also
contains a graphical indication
of aircraft vertical speeds, up
to 2,000 feet per minute. The
unit uses the same mechanical
mounting as a standard 3 inches
VSI, allowing it to easily replace
that instrument. It is compatible
with virtually all panel mounted
GPS navigation systems, providing an easy upgrade to add
color moving map technology
to older GPS systems. The unit
offers a high-resolution sunlight
readable color LCD moving map
display that includes both topview and side-view terrain presentations. Instantaneous height
above ground is also displayed
whenever the aircraft is below
10,000 feet AGL. Aspen Avionics
projects FAA certification in mid2005.
SWITCH / ANNUNCIATOR
UNITS
Some installations require
external switching to disable
certain functions or initiate the
built-in testing functions. Many of
the corporate jet and air transport installations use individual
switch/annunciators. The specific
STC will list the required switches and their placement in front of
the pilots. To simplify the instal-
lation, two units are available that
combine the necessary switching
and pilot alert functions into a
simple panel-mounted unit.
Mid-Continent Instruments
Mid-Continent Instrumentsʼ
MD-41 Terrain Awareness
Control Units provide annunciation, mode selection and automatic dimming capability. The
fully integrated, compact control
units do away with the need for
a myriad of switches, relays and
annunciators making installation
fast and easy. Both the MD411308 and the more compact
MD41-1208 present primary or
secondary visual alert of TAWS/
EGPWS within the pilotʼs direct
field-of-view. Mounted through
a single cutout in the panel, the
MD-41 reduces typical installation costs. ■
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