ACCIDENT Aircraft Type and Registration: Airbus A319

ACCIDENT Aircraft Type and Registration: Airbus A319
AAIB Bulletin: 1/2013
G-EZFV
EW/C2012/02/03
ACCIDENT
Aircraft Type and Registration: Airbus A319-111, G-EZFV
No & Type of Engines: 2 CFM56-5B5/3 turbofan engines
Year of Manufacture: Date & Time (UTC): 2010 (Serial no: 4327)
Location: London Luton Airport
Type of Flight: Commercial Air Transport (Passenger)
Persons on Board:
Crew - 6
Passengers - 142
Injuries:
Crew - None
Passengers - None
Nature of Damage: All landing gear legs exceeded their maximum certified
load
Commander’s Licence: Airline Transport Pilot’s Licence
Commander’s Age: 45 years
Commander’s Flying Experience: 10,700 hours (of which 500 were on type)
Last 90 days - 128 hours
Last 28 days - 61 hours
Captain U/T’s Licence: Airline Transport Pilot’s Licence
Captain U/T’s Age: 37 years
Captain U/T’s Flying Experience: 3,998 hours (of which 672 were on type)
Last 90 days - 170 hours
Last 28 days - 19 hours
Information Source: AAIB Field Investigation
14 February 2012 at 1359 hrs
Synopsis
The flight crew carried out a manually flown ILS
certified loads and were replaced; there was no other
approach to Runway 26 at London Luton Airport.
damage to the aircraft.
Shortly before touchdown, both pilots sensed the
History of the flight
aircraft was sinking and a go-around was initiated.
The aircraft made firm contact with the runway before
The aircraft was on a scheduled flight to London Luton
starting to climb. The normal acceleration recorded at
Airport, from Faro, Portugal. The pilot flying (PF) was
touchdown was 2.99g, which is classified as a Severe
a captain-under-training (Capt U/T), occupying the left
Hard Landing. The subsequent landing was uneventful.
seat; the right seat was occupied by a training captain,
All three landing gear legs exceeded their maximum
who was the commander of the aircraft.
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EW/C2012/02/03
The aircraft was inbound to Luton from the south
Stabilised approach criteria were met at 1,000 ft and
on the LOREL 4C standard arrival procedure. This
500 ft radio altitude (RA). The VAPP (final approach)
procedure requires the aircraft to cross the extended
speed was 129 kt and at 50 ft RA the approach remained
runway
the
stable. Just below 50 ft there was a small nose-up pitch
Runway 26 ILS/DME approach from the north. When
input followed by two nose-down inputs and, below
traffic allows, ATC will vector the aircraft towards the
50 ft, the flight data indicated an increasing rate of
final approach course before the arrival procedure is
descent from about 600 fpm to about 850 fpm. The data
completed, thereby shortening the track mileage to the
also showed that, below 100 ft RA, there were some left
landing. The flight crew were familiar with the airport
and right roll control inputs.
centreline,
before
positioning
for
procedures and were prepared for this to happen.
Below 30 ft, over the runway, both pilots sensed that
The aircraft was given an early radar vector towards
the aircraft was sinking rapidly and both initiated a
the final approach track and the PF increased the rate of
TOGA 102 go-around. The PF momentarily retarded
descent to close the correct descent profile from above.
the thrust levers to idle before advancing them to the
The aircraft was then allocated a heading of 220°M,
TOGA (Takeoff and Go-around) position. At the same
cleared to intercept the localiser and, once established, to
time, he made a full forward sidestick input, within
descend on the glidepath. The PF realised that the aircraft
one second, which was then rapidly reversed to full
would be high and configured the aircraft with flap 2 and
aft sidestick.
the landing gear down, to capture the 3º glideslope from
input, the commander initiated an aft sidestick input
above. He armed the localiser mode and then attempted
which reached the full aft position within one second.
to arm the approach mode but inadvertently selected
He followed through the PF, pushing the thrust levers
the EXPED pushbutton.
The expedite climb mode
fully forward and announced “I HAVE CONTROL”. The
engaged but, to prevent a climb or any mode confusion
aircraft made firm contact with the runway, on all three
and to regain the correct profile, the PF disconnected the
landing gear legs simultaneously, before lifting off and
autopilot and the autothrust. The aircraft passed through
starting to climb. During this phase the PF relinquished
the localiser and ATC issued a revised heading to enable
control and reverted to the PNF role.
1
As the PF made the forward sidestick
the aircraft to intercept from the south.
The commander remained as the PF, completed the
The PF decided to continue flying the approach manually
go-around and subsequently carried out an uneventful
and the aircraft was established on the localiser at
landing on the same runway. There were no reported
5.5 nm. It was configured for landing, with full flap, at
injuries.
5 nm. Landing clearance was issued at 1355 hrs, with a
Flight crew information
reported surface wind of 320°/15 kt. A subsequent wind
check of 320°/16 kt was broadcast at 1356 hrs, three
The Capt U/T had completed nine sectors of command
minutes before touchdown. The wind conditions were
training without notable incident and the training reports
gusty and gave rise to some turbulence on the approach.
prior to the event had all been positive. His command
Footnote
Footnote
EXPED - Expedite mode is used in climb or descent to reach the
desired altitude with the maximum vertical gradient.
1
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20
TOGA 10 Baulked landing procedure.
AAIB Bulletin: 1/2013
G-EZFV
training had included practice in TOGA 10 manoeuvres
EW/C2012/02/03
‘In the event of a rejected landing from flare
in the simulator but he had never carried out a TOGA 10
initiation until thrust reverser selection
manoeuvre in the aircraft.
• call “TOGA TEN”
The commander had previous experience of line training
• select TOGA
on another aircraft type, but was relatively inexperienced
• pitch to 10° (this may mean holding the
in this capacity on the Airbus 320 series aircraft. He
attitude or de-rotating to achieve or maintain
reported that he had practised TOGA 10 manoeuvres in
10° pitch.)
the simulator but this was his first experience of one in
the aircraft.
• do not retract the flaps until a positive rate of
climb is established.
Meteorological information
• When positive ROC confirmed, call “GO
The ATIS information issued at 1320 hrs, and copied
AROUND FLAPS” and apply normal go
by the crew, was surface wind from 300°M at 12 kt,
around procedure.’
CAVOK, temperature 7°C, dewpoint 3°C and pressure
1024 hPa. There was no significant change between
Through its Flight Data Monitoring programme, the
1320 hrs and 1400 hrs.
operator has carried out several analyses of TOGA 10
manoeuvres conducted by its crews. The most recent
Wind data was obtained from the Runway 26 touchdown
analysis, which was completed following a programme
zone sensor. Readings are taken every 10 minutes and
of TOGA 10 training for crews in the simulator,
include the average direction and speed reported, along
examined 67 events. The report concluded that the
with min/max variations. The readings for 1400 hrs
manoeuvre was generally well flown and there were no
were average wind direction from 315°M, varying
significant dual inputs recorded.
between 297°M and 342°M, and average wind speed
Aircraft information
13 kt, varying between 9 kt and 17 kt.
Autothrust
The crew were aware that some turbulence can be
The manufacturer provides the following information
expected on the final approach to Runway 26 when the
concerning the use of autothrust:
wind is from the north-west.
Baulked landing procedure
‘The A/THR is, in particular, best suited to
tracking a moving target speed, when flying in
The operator provides the following Baulked Landing
managed speed mode. Statistically, the A/THR
Procedure, entitled TOGA 10, in its operations manual.
provides the best protection against airspeed
Either pilot may carry out this manoeuvre.
excursions and its use is, therefore, recommended
even in turbulent conditions, unless thrust
variations become excessive.
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The operator provides the following guidance for flight
A/THR response to airspeed variations is
crew in their operations manual:
the result of a design compromise between
performance and comfort, and it is optimized
‘If a take-over becomes necessary during flight,
when the AP is engaged. Therefore, in turbulent
the PNF must call clearly “I have control”, and
conditions and when flying manually, the pilot
press the sidestick priority pushbutton, keeping
may sometimes find it to be too slow or lagging.’
it pressed until the transfer of control is clearly
Sidesticks
established. During critical phases of flight the
PNF should be in a position to takeover, this may
There is a sidestick for each pilot, located outboard of
be achieved by resting the hand on the console or
the seating position. There are two switches on the
indeed on the stick itself but it is imperative that
sidestick, one of which is the autopilot disconnect and
no input is made on the sidestick.’
sidestick takeover pushbutton. The sidestick controls
move independently, so one pilot may not be aware of a
The use of the takeover pushbutton has been shown
control input being made by the other.
from previous incidents not to be instinctive.3 Training
in taking over control, including the use of the takeover
The manufacturer advises:
pushbutton, is provided by the operator.
‘When the Pilot Flying (PF) makes an input on the
Flare Mode
sidestick, an order (an electrical signal) is sent to
the fly-by-wire computer. If the Pilot Not Flying
When the aircraft descends through 50 ft RA it enters
(PNF) also acts on the stick, then both signals/
Flare Mode. The manufacturer’s description is:
orders are added.’
‘The system memorizes the attitude at 50 ft, and
that attitude becomes the initial reference for
And:
pitch attitude control. As the aircraft descends
‘If the PNF (or Instructor) needs to take over, the
through 30 ft, the system begins to reduce the
PNF must press the sidestick takeover pushbutton,
pitch attitude, reducing it to 2° nose down over
and announce: “I have control”.’
a period of 8 s. This means that it takes gentle
nose-up action by the pilot to flare the aircraft.’
Further:
Engineering investigation
‘In the event of simultaneous input on both
The A319 is fitted with a system that senses when
sidesticks the two green SIDE STICK PRIORITY
landing parameters have been exceeded and generates
lights on the glareshield come on and “DUAL
a LOAD<15> report, following which inspection of the
INPUT” voice message is activated. A pilot can
aircraft for damage is required.
deactivate the other stick and take full control by
Footnote
pressing and keeping pressed his priority takeover
Ref ; AAIB Bulletin No: 11/2004 Airbus A320, C-GTDK, AAIB
Bulletin No: 5/2001 Airbus A321, D-AIRE and Airbus A321-211,
EI-CPE.
3
pushbutton.’
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Aircraft examination
A LOAD <15> report will automatically be generated
during a landing if any of the following conditions are
The operator sent the FDR data to the manufacturer.
met:
Due to the high level of vertical acceleration and the
fact that the aircraft had made a three-point landing,
• The normal acceleration is greater than 2.6g
the manufacturer requested a comprehensive list of
at touchdown (+/-0.5 second). If the aircraft
structural inspections which included several areas of
weight exceeds the maximum landing gross
the fuselage, the belly fairing, the pylons, the horizontal
weight, the normal acceleration limit is
stabilizer and the wings. No damage was found in these
reduced to 1.7g.
areas.
• The rate of descent on the radio altimeter
The manufacturer’s analysis confirmed that the
is greater than 9 ft/sec at touchdown
following components had exceeded their design loads
(+/ 0.5 second). If the aircraft weight exceeds
and needed to be replaced:
the maximum landing gross weight, the radio
altimeter descent rate limit is reduced to
• Nose Landing Gear shock absorber.
6 ft/sec.
•Left Main Gear sliding tube assembly
•During a bounced landing, the normal
(including shock absorber internals)
acceleration exceeds 2.6g.
• Right Main Gear Main fitting, including both
pintle pins
The normal acceleration parameter used within the
LOAD <15> report computation is provided by an
• Right Main Gear sliding tube assembly
accelerometer mounted near to the aircraft’s centre of
(including shock absorber internals)
gravity; the same accelerometer is used by the flight data
recorder (FDR) system. The accelerometer incorporates
The operator replaced all three landing gear legs, which
a filter that attenuates its output above a predefined
were returned to the landing gear manufacturer for
frequency. Under certain conditions, such as during
overhaul.
rapid changes in acceleration, the accelerometer output
Recorded flight data
may not always reflect the maximum attained normal
acceleration level. In addition, during various phases
The aircraft’s FDR and CVR were removed from the
of flight, acceleration levels experienced by other areas
aircraft, downloaded and the recordings were analysed
of the airframe, such as the nose gear, may be different
by the AAIB. Recordings on the CVR at the time of
from those measured at the centre of gravity.
the hard landing had been overwritten by more recent
recordings while the aircraft was on the ground, after the
A LOAD <15> report for the incident landing was
final landing.
automatically generated shortly after the hard landing,
having recorded a normal acceleration of 2.99g and a
From the FDR data it was determined that at 8.3 nm
rate of descent of 12.5 ft/sec.
DME range from Luton and a height of 3,500 ft agl,
the Expedite Climb Mode was selected. Three seconds
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later, the autothrust was disconnected, followed by the
down on all three landing gear simultaneously, during
autopilot. The Expedite Climb Mode was deselected
which a normal acceleration of 2.99 g was recorded.
after 10 seconds. The aircraft was established on the
The aircraft then lifted off, completed a go-around and
localizer at 5.5 nm DME and 2,000 ft agl. The flaps
returned for an uneventful landing.
were fully extended by 5.0 nm DME.
The manufacturer’s analysis of the data provided the
Figure 1 shows the salient recorded parameters
following information:
approaching the touchdown. The data illustrated starts
at 1358:38 hrs, with the aircraft at 200 ft agl, 130 kt
‘Inputs performed simultaneously by pilots
indicated airspeed and descending at 625 ft/min. At
were equivalent to a pitch down order at ~+7°
this point the aircraft’s attitude was 3º nose-up and
of side sick deflection leading to a strong pitch
2º left wing low. Left-seat sidestick control inputs
decrease.’
were made which resulted in the aircraft rolling wings
Analysis
level as it descended though 100 ft agl. The wings
remained level for just over one second before further
In the early stages of the approach there was a period
inputs rolled the aircraft right (to 4.5º at 60 ft agl), then
of increased workload for the PF, caused by the aircraft
left (to 5.5º at 21 ft agl), then back to wings level at
being above the nominal 3º descent profile. This was
touchdown.
exacerbated when the PF inadvertently selected the
Expedite Mode, instead of the Approach Mode, and
As the aircraft descended through 60 ft agl, at
missed intercepting the localiser. He recovered from
1358:46 hrs, a momentary 2º reduction in angle of
this by reverting to manual flight and the aircraft was
attack was recorded while the pitch attitude remained
re-established on the expected profile by 5 nm. This
steady at 3.5º nose-up. A maximum pitch attitude
does not appear to have directly affected the outcome of
of 4.2º occurred at 32 ft agl, 2.5 seconds before
the approach other than that it led to the PF’s decision
touchdown. This was followed by some pitch-down
to use manual thrust for the remainder of the approach,
control inputs (from the left seat) which resulted in
which increased the workload in turbulent conditions.
a decreasing pitch attitude, the descent rate peaking
at just under 900 ft/min, and the aircraft descended
The manufacturer advises the use of autothrust in most
below the nominal glideslope. The left-seat pilot then
circumstances but also notes that there are conditions
applied an aft sidestick control input of 10º (out of a
in which autothrust may not be the best option. Thus, it
maximum of 16º) which was coincident with a small
is accepted that a pilot may need to use manual thrust.
aft-stick input by the commander. Both thrust levers
were then advanced to the TOGA position. However,
Once established on the ILS in the landing configuration,
there was also a simultaneous forward sidestick input
the remainder of the approach was stable and it was only
of 15º from the left seat pilot, which was countered by
at a late stage that it deviated from what would normally
an aft input of 8º by the commander (ie a net input of 7º
be expected. There was a momentary reduction in
forward). Both sidesticks were then moved to the fully
angle of attack at about 60 ft agl and an increasing rate
aft position. Half a second later the aircraft touched
of descent below around 50 ft agl, with an increasing
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Figure 1
Salient FDR parameters for incident touchdown at Luton
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pitch attitude. The PF then made two brief nose-down
opposite to that expected and there was also a brief
inputs and the aircraft’s pitch attitude decreased. One
retardation of the thrust levers before they were
or all of these factors may have provided the cue to the
pushed forward to the TOGA position. One possible
pilots that the aircraft was sinking.
explanation is that there was momentary confusion
between the actions of his left and right hands.
As the pilots responded to the sink, a period of dual
The dual input phase
When the aircraft entered the Flare Mode at 50 ft the
lasted for approximately four seconds before the
pitch attitude was 3.2° nose-up. The system would have
commander established sole control and took over
ordered a nose-down pitch to reach 2° nose-up over a
as PF. Initially these dual inputs were in opposing
period of 8 seconds. However, this would have been a
directions, before the Capt U/T’s input was reversed.
relatively gradual change and was not considered to be
The commander made a nose-up control input on the
a significant factor in this event.
sidestick inputs was recorded.
sidestick but did not use the takeover pushbutton to
Following this event, the operator provided additional
establish control, so the effect was limited to reducing
simulator training for both pilots before returning them
the magnitude of the nose-down input made by the
to line flying duties. The Capt U/T was returned to line
Capt U/T. If the commander had used the sidestick
takeover pushbutton the severe hard landing may have
flying as a co-pilot for a period.
been prevented.
Conclusion
The brief nose-down inputs made by the Capt U/T
Both pilots responded to an increased rate of descent
occurred at a time when a nose-up control input would
approaching touchdown and each initiated a TOGA 10
normally be expected and probably took the commander
go-around.
by surprise. The sidesticks move independently. So
opposition and, without the use of the takeover sidestick
he would have had no knowledge of the inputs being
pushbutton, the net effect was a pitch-down control
made by the Capt U/T until the flightpath of the aircraft
input. If the commander had operated the sidestick
changed.
takeover pushbutton, his nose-up pitch input would not
Their initial sidestick inputs were in
have been counteracted by the nose-down input of the
In attempting to carry out the TOGA 10 manoeuvre,
Capt U/T. In the event, his control input reduced the
the Capt U/T appears to have made a sidestick input
effect of the nose-down input made by the Capt U/T.
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