Airbus crash question
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Airbus crash question
Following on a rising interest in Airbus, can anyone explain (simply please) what caused the crash that killed Nick Warner on the ?330? demo flight out of Toulouse, which 'law' he was in and why he was not 'protected' during the alt acquire/capture?
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BOAC, unable to find mention on the French BEA site but Flight Global has the following.
1994 | 1630 | Flight Archive
BY DAVID LEARMOUNT
The Airbus Industrie A330 which crashed at Toulouse during a test flight, lost directional control when its speed dropped dramatically after it was pitched up under autopilot control, according to data sent by Airbus to A330operators. Airbus says that "...analysis has not revealed any aircraft, engine, flight-control and autopilot system malfunction".
The consortium has told A330 operators that pilots who experience an engine failure at low speed should disconnect the autopilot and limit pitch-attitude. Airbus defines low speed as the minimum selectable autopilot speed (VLS), or 125kt (230km/h), whichever is the higher.
The accident happened during a simulated engine failure, when airspeed fell from the planned 150kt to only 100kt — then dropped to 90kt, while the pilot was taking over manual control — taking the aircraft well below VMCA [minimum control speed on a single engine at full power]. Airbus says that the floor" system did trigger, but "...was inhibited by the crew". Alpha-floor provides automatic full power on both engines when the angle of attack reaches a safe maximum.
The purpose of the flight was to test "experimental autopilot control-laws", the bulletin tells operators.
For the test, the left engine's thrust was selected to idle and its associated hydraulic system shut down. When directional control had been lost, the aircraft banked 110° to the left. The pilot had already taken manual control and begun to pull out of the dive, with wings level, but the height was insufficient for recovery.
The test intention, says the bulletin, was: "...to evaluate an experimental autoflight system developed for the A330 Pratt & Whitney version, at the limits of the flight envelope — maximum aft centre of gravity [CG], minimum [go-around] speed, with high rate of climb and engine failure — associated with the development of the autoland all-weather Category III operation".
Take-off conditions revealed in the bulletin were: configuration 2, weight 145t (very light), full aft [flight] CG (42%), fuel 23t and maximum take-off thrust selected. With these conditions the reference speeds were: V,, 126kt; V2, 126kt; VR, 135kt.
The flight history as notified to A330 operators included the following details:
• altitude set on autopilot flight control unit was 2,000ft (600m);
• unstick occurred at 136kt, 25s after power application;
• pitch attitude was "driven up to 28°" to maintain 150kt;
• at 150kt, 6s after unstick, the autopilot was engaged, number one engine selected to idle and the blue-system hydraulic circuit switched off;
• "...as expected the aircraft's pitch angle started to decrease from 29° to 25°";
• then, however, because of the low selected altitude, the autopilot reverted to the "altstar" mode (altitude acquire mode), "...thus preventing the intended task completion". At that point the aircraft began to pitch up again. Airbus believes that the unwanted pitch-up was because of "alt-star" mode demands when the aircraft's rate of climb began to decrease following loss of power on the engine. "The crew immediately identified the subsequent speed and pitch evolution and let the situation develop, most probably to enable proper recording of the event.";
• "...the aircraft reached a pitch of 33° and the speed reduced rapidly to lOOkt, which is 18kt below Vmca";
• the pilot took manual control: "Speed continued to decrease and the aircraft suffered an uncontrollable lateral departure at about 90kt." The aircraft hit the ground 35s after unstick.
ASN says PROBABLE CAUSES: "At the present stage of its work, the commission estimates that the accident can be explained by a combination of several factors none of which, taken separately, would have led to an accident.
The initial causes are primarily related to the type of the test and its execution by the crew during the last takeoff:
1) choice of maximum power (TOGA) instead of Flex 49; 2) very aft CG for the last takeoff; 3} trim set in the takeoff range, but in too high a nose-up position; 4) selected altitude of 2000 feet; 5) imprecise and late definition of the test to be conducted and the tasks to be performed by the captain and first officer, respectively; 6) positive and very rapid rotation executed by the first officer; 7) the captain was busy with the test operations to be performed immediately after take off (engagement of the autopilot, reduce thrust on the engine and cut off the blue hydraulic system) which temporarily placed him outside the control loop; 8) in addition the absence of pitch attitude protection in the autopilot altitude acquisition mode played a significant role.
The following is also contributed to the accident: 1) The inability of the crew to identify the mode in which the autopilot was placed; 2) the confidence of the crew in the expected reactions of the aircraft; 3) the late reaction from the flight test engineer when faced with a potentially hazardous change in parameters (speed in particular); 4) the time taken by the captain to react to an abnormal situation."
1994 | 1630 | Flight Archive
BY DAVID LEARMOUNT
The Airbus Industrie A330 which crashed at Toulouse during a test flight, lost directional control when its speed dropped dramatically after it was pitched up under autopilot control, according to data sent by Airbus to A330operators. Airbus says that "...analysis has not revealed any aircraft, engine, flight-control and autopilot system malfunction".
The consortium has told A330 operators that pilots who experience an engine failure at low speed should disconnect the autopilot and limit pitch-attitude. Airbus defines low speed as the minimum selectable autopilot speed (VLS), or 125kt (230km/h), whichever is the higher.
The accident happened during a simulated engine failure, when airspeed fell from the planned 150kt to only 100kt — then dropped to 90kt, while the pilot was taking over manual control — taking the aircraft well below VMCA [minimum control speed on a single engine at full power]. Airbus says that the floor" system did trigger, but "...was inhibited by the crew". Alpha-floor provides automatic full power on both engines when the angle of attack reaches a safe maximum.
The purpose of the flight was to test "experimental autopilot control-laws", the bulletin tells operators.
For the test, the left engine's thrust was selected to idle and its associated hydraulic system shut down. When directional control had been lost, the aircraft banked 110° to the left. The pilot had already taken manual control and begun to pull out of the dive, with wings level, but the height was insufficient for recovery.
The test intention, says the bulletin, was: "...to evaluate an experimental autoflight system developed for the A330 Pratt & Whitney version, at the limits of the flight envelope — maximum aft centre of gravity [CG], minimum [go-around] speed, with high rate of climb and engine failure — associated with the development of the autoland all-weather Category III operation".
Take-off conditions revealed in the bulletin were: configuration 2, weight 145t (very light), full aft [flight] CG (42%), fuel 23t and maximum take-off thrust selected. With these conditions the reference speeds were: V,, 126kt; V2, 126kt; VR, 135kt.
The flight history as notified to A330 operators included the following details:
• altitude set on autopilot flight control unit was 2,000ft (600m);
• unstick occurred at 136kt, 25s after power application;
• pitch attitude was "driven up to 28°" to maintain 150kt;
• at 150kt, 6s after unstick, the autopilot was engaged, number one engine selected to idle and the blue-system hydraulic circuit switched off;
• "...as expected the aircraft's pitch angle started to decrease from 29° to 25°";
• then, however, because of the low selected altitude, the autopilot reverted to the "altstar" mode (altitude acquire mode), "...thus preventing the intended task completion". At that point the aircraft began to pitch up again. Airbus believes that the unwanted pitch-up was because of "alt-star" mode demands when the aircraft's rate of climb began to decrease following loss of power on the engine. "The crew immediately identified the subsequent speed and pitch evolution and let the situation develop, most probably to enable proper recording of the event.";
• "...the aircraft reached a pitch of 33° and the speed reduced rapidly to lOOkt, which is 18kt below Vmca";
• the pilot took manual control: "Speed continued to decrease and the aircraft suffered an uncontrollable lateral departure at about 90kt." The aircraft hit the ground 35s after unstick.
ASN says PROBABLE CAUSES: "At the present stage of its work, the commission estimates that the accident can be explained by a combination of several factors none of which, taken separately, would have led to an accident.
The initial causes are primarily related to the type of the test and its execution by the crew during the last takeoff:
1) choice of maximum power (TOGA) instead of Flex 49; 2) very aft CG for the last takeoff; 3} trim set in the takeoff range, but in too high a nose-up position; 4) selected altitude of 2000 feet; 5) imprecise and late definition of the test to be conducted and the tasks to be performed by the captain and first officer, respectively; 6) positive and very rapid rotation executed by the first officer; 7) the captain was busy with the test operations to be performed immediately after take off (engagement of the autopilot, reduce thrust on the engine and cut off the blue hydraulic system) which temporarily placed him outside the control loop; 8) in addition the absence of pitch attitude protection in the autopilot altitude acquisition mode played a significant role.
The following is also contributed to the accident: 1) The inability of the crew to identify the mode in which the autopilot was placed; 2) the confidence of the crew in the expected reactions of the aircraft; 3) the late reaction from the flight test engineer when faced with a potentially hazardous change in parameters (speed in particular); 4) the time taken by the captain to react to an abnormal situation."
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Thanks indeed, Brian. Has the "absence of pitch attitude protection in the autopilot altitude acquisition mode" been addressed, do you know.
I must admit that "The following also contributed to the accident:" items 1 and 2 have a chilling ring to them. Considering Nick was CTP..........................................
I must admit that "The following also contributed to the accident:" items 1 and 2 have a chilling ring to them. Considering Nick was CTP..........................................
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BOAC, I'm afraid I know nothing other than what is in the article. The co-pilot was a airline pilot (Alitalia?) who was along for a demonstration ride, as were other pilots on board - not rated in the aircraft as I recall, and certainly not a "test pilot". (All from an aging memory)
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A little more 1994 | 1864 | Flight Archive
A330 crash caused by series of small errors
DAVID LEAR MOUNT
A series of small errors combined to cause the crash of the Airbus A3 30 during tests at Toulouse on 30 June, says the official inquiry's interim report.
Describing the events that took place at Blagnac airfield, the report portrays a tired captain, flying at the end of an extremely busy day with an incompletely briefed crew.
The commission of enquiry within the DGA, the French military body which investigates test flight accidents, highlights "...a combination of several factors, no one of which, in isolation, would have caused the crash".
The fatal take-off was the second in a sortie designed to test the new autopilot system under critical engine-out conditions immediately after take-off.
During the first take-off, the crew had carried out the test successfully, then flew engine-out goarounds twice. The crew then made a full-stop landing and taxied- round for another take-off, by which time the sortie had already lasted for 55min.
The captain, Airbus chief test pilot Nick Warner, had flown the first take-off, but for the second he gave control to the co-pilot, Michel Cais, an Air Inter training captain who had been working with the Airbus training organization Aeroformation.
Warner must have been tired after a punishingly busy day, says the report. Before starting the test flight, he had already captained an A321 demonstration flight, supervised a simulator session and attended two meetings, including a briefing for journalists.
Criticising the lack of a complete pre-flight briefing, the report relates this to Warner's busy schedule. It also remarks that the crew may have become complacent because the tests up to "the last take-off" had gone perfectly.
Under the heading "probable causes", the Commission then lists three groups of contributory factors, the first of which were related to the test-flight tasks immediately after take-off.
Maximum thrust [take-take-off/goaround (TOGA)] was chosen by the captain, instead of setting "Flex 49", which was die high power setting specified in the test plan. This meant that, when he simulated failure of the left engine immediately after take-off, asymmetric forces were higher than planned.
The aircraft centre of gravity (CG) was at maximum aft setting of 42%, while the trim was set at 2.2° nose-up. Although the trim setting was within acceptable limits, it was inappropriate, given the aft CG. These two factors together increased the risk of fast over-rotation.
The autopilot was also left set for altitude-capture at 2,000ft (600m), which meant that the mode became active within seconds of take-off.
The report warns that the absence of attitude-protection in the autopilot altitude-acquire mode "played a critical role" in the accident.
According to the report, die next group of factors related to uncertainty in the allocation of tasks between captain and co-pilot. The co-pilot rotated the aircraft for take-off "firmly and very fast" to an attitude more than 25°, compared with 14.5° at first take-off.
Immediately after take-off, the captain then carried out the test procedures: autopilot engage, throttle-back port engine and trip circuit-breaker for blue hydraulic circuit. The report says that he therefore became temporarily "out of the piloting loop".
Ancillary factors played an equally important part in the accident, comments the report.
These include:
• the lack of autopilot-mode visual indication because the exceptional pitch attitude obscured it on the primary flight display;
• crew confidence in how they expected the aircraft to react;
• the delayed reaction of the test engineer to developing parameters, particularly speed;
• "the captain's slowness in reacting to the development of an abnormal situation".
Interim recommendations
• Advise A3 30 operators of the need to monitor aircraft airspeed behaviour if they are in autopilot altitude-capture mode during the climb and an engine fails;
• conduct tests to ensure that this mode poses no risks in line usage;
• whatever is found, seek solutions to improve flight-envelope protection in this mode to make it the same as in all other modes;
• carry out similar tests on all other aircraft types which have similar autopilot systems;
• review the regulations concerning who, in addition to the basic crew, may fly on test flights;
• test flights should be preceded by a formal briefing, even if the test is routine. This should include any planned, authorised re-allocation of tasks during the flight.
A330 crash caused by series of small errors
DAVID LEAR MOUNT
A series of small errors combined to cause the crash of the Airbus A3 30 during tests at Toulouse on 30 June, says the official inquiry's interim report.
Describing the events that took place at Blagnac airfield, the report portrays a tired captain, flying at the end of an extremely busy day with an incompletely briefed crew.
The commission of enquiry within the DGA, the French military body which investigates test flight accidents, highlights "...a combination of several factors, no one of which, in isolation, would have caused the crash".
The fatal take-off was the second in a sortie designed to test the new autopilot system under critical engine-out conditions immediately after take-off.
During the first take-off, the crew had carried out the test successfully, then flew engine-out goarounds twice. The crew then made a full-stop landing and taxied- round for another take-off, by which time the sortie had already lasted for 55min.
The captain, Airbus chief test pilot Nick Warner, had flown the first take-off, but for the second he gave control to the co-pilot, Michel Cais, an Air Inter training captain who had been working with the Airbus training organization Aeroformation.
Warner must have been tired after a punishingly busy day, says the report. Before starting the test flight, he had already captained an A321 demonstration flight, supervised a simulator session and attended two meetings, including a briefing for journalists.
Criticising the lack of a complete pre-flight briefing, the report relates this to Warner's busy schedule. It also remarks that the crew may have become complacent because the tests up to "the last take-off" had gone perfectly.
Under the heading "probable causes", the Commission then lists three groups of contributory factors, the first of which were related to the test-flight tasks immediately after take-off.
Maximum thrust [take-take-off/goaround (TOGA)] was chosen by the captain, instead of setting "Flex 49", which was die high power setting specified in the test plan. This meant that, when he simulated failure of the left engine immediately after take-off, asymmetric forces were higher than planned.
The aircraft centre of gravity (CG) was at maximum aft setting of 42%, while the trim was set at 2.2° nose-up. Although the trim setting was within acceptable limits, it was inappropriate, given the aft CG. These two factors together increased the risk of fast over-rotation.
The autopilot was also left set for altitude-capture at 2,000ft (600m), which meant that the mode became active within seconds of take-off.
The report warns that the absence of attitude-protection in the autopilot altitude-acquire mode "played a critical role" in the accident.
According to the report, die next group of factors related to uncertainty in the allocation of tasks between captain and co-pilot. The co-pilot rotated the aircraft for take-off "firmly and very fast" to an attitude more than 25°, compared with 14.5° at first take-off.
Immediately after take-off, the captain then carried out the test procedures: autopilot engage, throttle-back port engine and trip circuit-breaker for blue hydraulic circuit. The report says that he therefore became temporarily "out of the piloting loop".
Ancillary factors played an equally important part in the accident, comments the report.
These include:
• the lack of autopilot-mode visual indication because the exceptional pitch attitude obscured it on the primary flight display;
• crew confidence in how they expected the aircraft to react;
• the delayed reaction of the test engineer to developing parameters, particularly speed;
• "the captain's slowness in reacting to the development of an abnormal situation".
Interim recommendations
• Advise A3 30 operators of the need to monitor aircraft airspeed behaviour if they are in autopilot altitude-capture mode during the climb and an engine fails;
• conduct tests to ensure that this mode poses no risks in line usage;
• whatever is found, seek solutions to improve flight-envelope protection in this mode to make it the same as in all other modes;
• carry out similar tests on all other aircraft types which have similar autopilot systems;
• review the regulations concerning who, in addition to the basic crew, may fly on test flights;
• test flights should be preceded by a formal briefing, even if the test is routine. This should include any planned, authorised re-allocation of tasks during the flight.
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BA - most grateful for your 'digging'. Hopefully if the interim recs were seen through, another 'tired and unprepared' crew will be protected.
