Airbus crash/training flight
As someone who has flown many post-major servicing maintenance test flights on the VC10K, the thing which immediately struck me when reading the CVR transcript was the woeful attitude towards flight testing exhibited by the crew.
I see no indication of a pre-planned flight, no indication of a test card with mandatory height/speed/configuration test points, just an "OK, I think we'll do this next" attitude - and rather weak knowledge of the characteristics of the flight laws.
Post-maintenance testing requires a highly disciplined approach, an experienced test team and a thoroughly pre-briefed flight with prepared test cards. It isn't the same as raw 'test flying' and doesn't necessarily need a fully qualified TP, but it DOES require a selected and well-trained crew with better than normal aircraft system knowledge.
Unexpected things may well happen during post-maintenance test flying - I once last half of the entire electrical system and all attitude instruments until we managed to relight the associated engine and get its alternator on line. (Good thing we didn't drop the ELRAT; on the next test flight its alternator control unit caught fire causing smoke on the flight deck during the approach...
)
I see no indication of a pre-planned flight, no indication of a test card with mandatory height/speed/configuration test points, just an "OK, I think we'll do this next" attitude - and rather weak knowledge of the characteristics of the flight laws.
Post-maintenance testing requires a highly disciplined approach, an experienced test team and a thoroughly pre-briefed flight with prepared test cards. It isn't the same as raw 'test flying' and doesn't necessarily need a fully qualified TP, but it DOES require a selected and well-trained crew with better than normal aircraft system knowledge.
Unexpected things may well happen during post-maintenance test flying - I once last half of the entire electrical system and all attitude instruments until we managed to relight the associated engine and get its alternator on line. (Good thing we didn't drop the ELRAT; on the next test flight its alternator control unit caught fire causing smoke on the flight deck during the approach...
)
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Thanks Thunderbug & NOD
I've looked at the diagram on page 94 of the report and can see the entrance route of the water. I understood that the body/internal moving parts of the sensor was heated, but they're not, just the external vane. The fuselage seal is a difficult one to design out given that the vane must freely rotate; internal heating of the body of the sensor is a start.
I've looked at the diagram on page 94 of the report and can see the entrance route of the water. I understood that the body/internal moving parts of the sensor was heated, but they're not, just the external vane. The fuselage seal is a difficult one to design out given that the vane must freely rotate; internal heating of the body of the sensor is a start.
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...internal heating of the body of the sensor is a start
I suppose it comes down to whether the "basic cause" of the accident was HF based, or Technical? To "blame" the AoA sensors means Technical. To me, it was a HF accident unfortunately.
As I said, I fly A320s for a job, with Pax down the back, in all sorts of weather. I have no cause for concern over the AoA sensors as fitted.
NoD
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NOD
Agreed, but like all accidents it's a series of holes lining up together,
1 Incorrect maintenance (washing)
2 Water penetrating parts of the gubbins
3 Icing
4 Crew not trained for the task
If just one of these holes had been closed do you think the accident would have happened?
I'm pleased with your comments re Airbus AoA sensors. Thanks
Agreed, but like all accidents it's a series of holes lining up together,
1 Incorrect maintenance (washing)
2 Water penetrating parts of the gubbins
3 Icing
4 Crew not trained for the task
If just one of these holes had been closed do you think the accident would have happened?
I'm pleased with your comments re Airbus AoA sensors. Thanks
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Would this be a fair assesment?. Came from the accident investigation.
PROBABLE CAUSE:
The loss of control of the aeroplane by the crew following the improvised demonstration of the functioning of the angle of attack protections, while the blockage of the angle of attack sensors made it impossible for these protections to trigger.
The crew was not aware of the blockage of the angle of attack sensors. They did not take into account the speeds mentioned in the programme of checks available to them and consequently did not stop the demonstration before the stall.
??The following factors contributed to the accident:
* The decision to carry out the demonstration at a low height;
* The crew’s management, during the thrust increase, of the strong increase in the longitudinal pitch, the crew not having identified the pitch-up stop position of the horizontal stabiliser nor acted on the trim wheel to correct it, nor reduced engine thrust;
* The crew having to manage the conduct of the flight, follow the programme of in-flight checks, adapted during the flight, and the preparation of the following stage, which greatly increased the work load and led the crew to improvise according to the constraints encountered;
* The decision to use a flight programme developed for crews trained for test flights, which led the crew to undertake checks without knowing their aim;
* The absence of a regulatory framework in relation to non-revenue flights in the areas of air traffic management, of operations and of operational aspects;
* The absence of consistency in the rinsing task in the aeroplane cleaning procedure, and in particular the absence of protection of the AOA sensors, during rinsing with water of the aeroplane three days before the flight. This led to the blockage of the AOA sensors through freezing of the water that was able to penetrate inside the sensor bodies.
The following factors also probably contributed to the accident
* Inadequate coordination between an atypical team composed of three airline pilots in the cockpit;
* The fatigue that may have reduced the crew’s awareness of the various items of information relating to the state of the systems
PROBABLE CAUSE:
The loss of control of the aeroplane by the crew following the improvised demonstration of the functioning of the angle of attack protections, while the blockage of the angle of attack sensors made it impossible for these protections to trigger.
The crew was not aware of the blockage of the angle of attack sensors. They did not take into account the speeds mentioned in the programme of checks available to them and consequently did not stop the demonstration before the stall.
??The following factors contributed to the accident:
* The decision to carry out the demonstration at a low height;
* The crew’s management, during the thrust increase, of the strong increase in the longitudinal pitch, the crew not having identified the pitch-up stop position of the horizontal stabiliser nor acted on the trim wheel to correct it, nor reduced engine thrust;
* The crew having to manage the conduct of the flight, follow the programme of in-flight checks, adapted during the flight, and the preparation of the following stage, which greatly increased the work load and led the crew to improvise according to the constraints encountered;
* The decision to use a flight programme developed for crews trained for test flights, which led the crew to undertake checks without knowing their aim;
* The absence of a regulatory framework in relation to non-revenue flights in the areas of air traffic management, of operations and of operational aspects;
* The absence of consistency in the rinsing task in the aeroplane cleaning procedure, and in particular the absence of protection of the AOA sensors, during rinsing with water of the aeroplane three days before the flight. This led to the blockage of the AOA sensors through freezing of the water that was able to penetrate inside the sensor bodies.
The following factors also probably contributed to the accident
* Inadequate coordination between an atypical team composed of three airline pilots in the cockpit;
* The fatigue that may have reduced the crew’s awareness of the various items of information relating to the state of the systems
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Contributary Factors
I am surprised that the summary doesn't mention the unhelpful, to put it mildly, attitude of ATC, though it is discussed in the main body of the report (section 2.1.3, page 86 in the English version/90 in French). It was their baffling refusal to allow a few measly 360s that caused the whole low speed test first to be cancelled and then later inserted at a wholly inappropriate point in the flight. It also encouraged the crew to keep their later intentions to themselves. The obstinate and bureaucratic 'you can't do that there here' attitude, with no explanation, has a lot to answer for and should have no place in aviation, but is sadly common. This crew was not the first to be tripped up by a sudden ATC-inspired change to a flight test schedule, the A 330 accident at Toulouse in 1994 is a case in point.
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Need to set trim
When I read the whole report what struck me was that even with everything that was done wrong, I think they almost saved it at the end and would have made it if it was not for the trim being against the end stop. The warning about manual trim required vanished off the FD when it shifted into the unusual attitude mode (Abnormal Alternate Law).
I'm just an SLF with a strong interest in aviation, but is there not a case to be made for some form of highlighting what the trim is and the need to manually correct it in this type of scenario? I appreciate that there's going to be a ton of sounds going off and lights flashing, so not quite sure how to achieve it. Maybe add a "Check Trim" to the stall recovery checklist?
I'm just an SLF with a strong interest in aviation, but is there not a case to be made for some form of highlighting what the trim is and the need to manually correct it in this type of scenario? I appreciate that there's going to be a ton of sounds going off and lights flashing, so not quite sure how to achieve it. Maybe add a "Check Trim" to the stall recovery checklist?
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Jesus H Christ!
Does anybody actually read the thread? Or are many so hell bent on posting, you just post anyway?
How hard is this? Every flight is a serious event; a post-maintenance flight even more so. A post maintenance flight involving testing of systems is particularly delicate. This crew stuffed it up.
End of story.
Does anybody actually read the thread? Or are many so hell bent on posting, you just post anyway?
How hard is this? Every flight is a serious event; a post-maintenance flight even more so. A post maintenance flight involving testing of systems is particularly delicate. This crew stuffed it up.
End of story.
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gonebutnotforgotten
What are you talking about? What unhelpful attitude from ATC?
This crew filed a flight plan that made no mention of the manoeuvres that they were planning to fly, and was described by one controller as a "disguised test flight", so who was tripping up whom?
It seems that another aircraft from the same company had played that game earlier in the day, creating coordination issues for ATC, with a "few measly 360s". So ATC were not about to be bitten twice. Whose fault is that?
If the crew had requested a "real" test flight, I'm pretty sure that ATC would have obliged, but as the crew didn't seem to know what they were doing themselves, how could they?
Sorry, ATC didn't trip anyone up in this case, and I fail to see how ATC contributed to the A330 loss in Toulouse.
Have you just got something against French ATC?
TTFN
What are you talking about? What unhelpful attitude from ATC?
This crew filed a flight plan that made no mention of the manoeuvres that they were planning to fly, and was described by one controller as a "disguised test flight", so who was tripping up whom?
It seems that another aircraft from the same company had played that game earlier in the day, creating coordination issues for ATC, with a "few measly 360s". So ATC were not about to be bitten twice. Whose fault is that?
If the crew had requested a "real" test flight, I'm pretty sure that ATC would have obliged, but as the crew didn't seem to know what they were doing themselves, how could they?
Sorry, ATC didn't trip anyone up in this case, and I fail to see how ATC contributed to the A330 loss in Toulouse.
Have you just got something against French ATC?
TTFN
I agree about ATC: try doing an approach into LHR then ask for a couple of 'touch and goes', a few asymmetric circuits and a flapless landing... I think you might get a rather terse reply.
Airspace all over Europe is busy - delays at choke points and level restrictions are common, especially when the military are using their bits. To expect to fly a test profile without checking beforehand is relying on pure luck; how many aircraft on revenue flights had been planned through that area?
Slightly more on topic, I feel sorry for the two line pilots who paid the ultimate price... I remember being called out long ago for a test flight as a 2-ringer with less than a years experience. We rattled through a schedule and half the stuff went wrong: the pressurisation failed totally and we couldn't relight one of the engines, amongst other things. At the time I thought it was great fun as I was actually doing the flying, shutting down engines, Mmo runs, etc. - now, I'm not so sure it was a good idea and I think I was naive in the extreme to accept this flight with no training or briefing. Unfortunately, as spelt out in the report, there seems to be no official guide/framework as to how you qualify to execute sorties such as this.
The 3rd guy on the jumpseat should have really known better, though - he *was* qualified and experienced in this line of work.
Airspace all over Europe is busy - delays at choke points and level restrictions are common, especially when the military are using their bits. To expect to fly a test profile without checking beforehand is relying on pure luck; how many aircraft on revenue flights had been planned through that area?
Slightly more on topic, I feel sorry for the two line pilots who paid the ultimate price... I remember being called out long ago for a test flight as a 2-ringer with less than a years experience. We rattled through a schedule and half the stuff went wrong: the pressurisation failed totally and we couldn't relight one of the engines, amongst other things. At the time I thought it was great fun as I was actually doing the flying, shutting down engines, Mmo runs, etc. - now, I'm not so sure it was a good idea and I think I was naive in the extreme to accept this flight with no training or briefing. Unfortunately, as spelt out in the report, there seems to be no official guide/framework as to how you qualify to execute sorties such as this.
The 3rd guy on the jumpseat should have really known better, though - he *was* qualified and experienced in this line of work.
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BWB
"I've no time for sentimental notions of a fictional 'band of brothers'. The pilots of this A320 were not 21 years old. They knew better. If they didn't know better, they should not have been charged with the responsibility they had. It's as simple as that. Fallen comrades is bollocks. So is blaming Airbus. Damn the French, but not for this."
Agreed but the one thing I find worrying about this and the B737 manual reversion check flight event cross referenced in the report is that in both cases all of the pilots involved appeared to have forgotten a basic fying principle - if you cannot control the a/c in pitch the first thing to do is trim. Yes, a trimmable stab has to be used carefully but it has to be used ! Even though auto trim is the norm and the Airbus sidestick uses spring feel rather than feel related to dynamic pressure the principle of trimming an aeroplane remains the responsibility of the handling pilot. In events where the a/c is plainly not in control in pitch it should also be the first thing checked (via stab position) by the non-flying pilot. It seems that the industry training methods and recurrent training methods are seriously deficient if there are pilots out there who don't understand this or, heaven forbid, have forgotten the basics and are more system operators than pilots. And don't give me the spiel about auto paralysis and SOPs and following the book - what's wrong with the Mark 1 computer when the chips are down.
"I've no time for sentimental notions of a fictional 'band of brothers'. The pilots of this A320 were not 21 years old. They knew better. If they didn't know better, they should not have been charged with the responsibility they had. It's as simple as that. Fallen comrades is bollocks. So is blaming Airbus. Damn the French, but not for this."
Agreed but the one thing I find worrying about this and the B737 manual reversion check flight event cross referenced in the report is that in both cases all of the pilots involved appeared to have forgotten a basic fying principle - if you cannot control the a/c in pitch the first thing to do is trim. Yes, a trimmable stab has to be used carefully but it has to be used ! Even though auto trim is the norm and the Airbus sidestick uses spring feel rather than feel related to dynamic pressure the principle of trimming an aeroplane remains the responsibility of the handling pilot. In events where the a/c is plainly not in control in pitch it should also be the first thing checked (via stab position) by the non-flying pilot. It seems that the industry training methods and recurrent training methods are seriously deficient if there are pilots out there who don't understand this or, heaven forbid, have forgotten the basics and are more system operators than pilots. And don't give me the spiel about auto paralysis and SOPs and following the book - what's wrong with the Mark 1 computer when the chips are down.
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There is a serious breach of Airbus in the certification standards. The CS 25 document requires, paragraph 1309 (c), that pilots be informed of any failure so they can take appropriate action. If the pilots had been warned that 2 sensors were blocked, they never tried to test the proper operation of protection systems in which these probes are the main element.
CS 25.1309
(c) Information concerning unsafe system operating conditions must be provided to the crew to enable them to take appropriate corrective action. A warning indication must be provided if immediate corrective action is required. Systems and controls, including indications and annunciations must be designed to minimise crew errors, which could create additional hazards
CS 25.1309
(c) Information concerning unsafe system operating conditions must be provided to the crew to enable them to take appropriate corrective action. A warning indication must be provided if immediate corrective action is required. Systems and controls, including indications and annunciations must be designed to minimise crew errors, which could create additional hazards
Mistrust in Management
Spa83
The CS 25 document requires, paragraph 1309 (c), that pilots be informed of any failure so they can take appropriate action. If the pilots had been warned that 2 sensors were blocked, they never tried to test the proper operation of protection systems in which these probes are the main element.
Regards
Exeng
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Not trying to blame this crew as they are now unable to defend themselves.
As said previously, in general pilots are getting away from the basics!
If you are testing something during test, you should be expecting it not to work or fail. If not why do the test? If you are expecting the test to fail have sufficient alt to recover.
Any low speed work at least bug Vref, or better still the Vs for the weight and configuration of the aircraft.
Auto trim? Now that to me is scary.
As said previously, in general pilots are getting away from the basics!
If you are testing something during test, you should be expecting it not to work or fail. If not why do the test? If you are expecting the test to fail have sufficient alt to recover.
Any low speed work at least bug Vref, or better still the Vs for the weight and configuration of the aircraft.
Auto trim? Now that to me is scary.
Last edited by doubleu-anker; 18th Sep 2010 at 13:24.
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Originally Posted by exeng
Nobody was aware that the angle of attack sensors were inoperative so how could the Pilots be informed of this?
'CS 25.1309
(c) Information concerning unsafe system operating conditions must be provided to the crew to enable them to take appropriate corrective action. A warning indication must be provided if immediate corrective action is required. Systems and controls, including indications and annunciations must be designed to minimise crew errors, which could create additional hazards'
I would have expected an aircraft, which is supposed to be all things to all pilots, to know when 2 of its 3 PRIMARY sensors have 'failed' and therefore disagreed with the third. It is not even as if all 3 had failed at the same alpha when the warning system would need to be extra-clever.
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Exeng,
Have a look at the page 33 English version :
This is an absolute shame !
Have a look at the page 33 English version :
A voting mechanism allows rejection of the source of information that presents a difference from the two others. This vote is not apparent for the pilots
Originally Posted by BOAC
I would have expected an aircraft, which is supposed to be all things to all pilots, to know when 2 of its 3 PRIMARY sensors have 'failed' and therefore disagreed with the third. It is not even as if all 3 had failed at the same alpha when the warning system would need to be extra-clever.
Airbus is not all things to all pilots! Whoever is subscribing to this is buying marketing hype that has no connection to reality whatsoever! It's just another aeroplane. Granted, it has some quirks but when it comes down to basics, everything DP Davies wrote still holds true for the Airbi and one cannot choose to disregard it at his own peril as no Airbus is single seater! Airbus Industries attempt to create foolproof aeroplane has spectacularly failed, it only proved old maxim that nothing is foolproof because fools are so ingenious.
Extra clever computers? Alow me to use analogy; you are flying in IMC and unbeknownst to you two of your three EADIs start toppling simultaneously at the same rate, in the same direction. There are no ATT flags, just two ADIs that agree but are wrong and one that is right. Would you really be smarter than ELACs/FACs that outwoted the truthsaying AoA probe in favor of other two that agreed, yet their output, while valid, had no semblance to actual AoA?
The AoA sensors did not fail outright - they kept transmitting measured angle of AoA vanes, which did not match actual one as their pivoting mechanism was frozen. There is no protection against this kind of insidious failure except having good idea what the aroplane should be doing, being alert to what it is doing and not going over any discrepancy lightly . CHECK GW was subtle hint that something was wrong, yet it wasn't picked up by the crew. Acceptance test pilots should be very well acquainted with conditions that trigger the message. IMHO, seeing this on test flight is reason enough to cut the flight short and return the aeroplane to maintenance.
Originally Posted by SPA83
There is a serious breach of Airbus in the certification standards. The CS 25 document requires, paragraph 1309 (c), that pilots be informed of any failure so they can take appropriate action. If the pilots had been warned that 2 sensors were blocked, they never tried to test the proper operation of protection systems in which these probes are the main element.
Originally Posted by CDA
It seems that the industry training methods and recurrent training methods are seriously deficient if there are pilots out there who don't understand this or, heaven forbid, have forgotten the basics and are more system operators than pilots.
So we have the final report. Now I know what it takes to regain autotrim after going into abnormal attitude law. Blooming shame it wasn't in FCOM. One thing I can't understand, however; there were a couple of seconds between stall warning and beginning of tumble, pilot's input was stick forward, control law was still normal and yet the THS remained stuck. Can someone shed some light on this?
How do they do that?
Anyone have a thought on how the investigators differentiate between fresh water that entered the sensor before the flight and sea water (if any) that entered between the time of the crash and the recovery?
Mickjoebill
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CONFiture wrote:
Good reading here: https://secure.wikimedia.org/wikiped...ntine_generals
It also depends upon the various allowed deltas between the values (at least in a continuous system)...
fc101
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Exeng,
Have a look at the page 33 English version :
Quote:
A voting mechanism allows rejection of the source of information that presents a difference from the two others. This vote is not apparent for the pilots
This is an absolute shame !
Have a look at the page 33 English version :
Quote:
A voting mechanism allows rejection of the source of information that presents a difference from the two others. This vote is not apparent for the pilots
This is an absolute shame !
It also depends upon the various allowed deltas between the values (at least in a continuous system)...
fc101
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@clandestino
"Would you really be smarter than ELACs/FACs that outwoted the truthsaying AoA probe in favor of other two that agreed, yet their output, while valid, had no semblance to actual AoA?"
The computer may not be able to 'decide' which values might be correct, but there could easily be an oral /visual warning, that there is a disagreement within the three AoA probes.
"CHECK GW was subtle hint that something was wrong, yet it wasn't picked up by the crew"
The German BFU has commented on this displayed message in Appendix 18 of the report and even the response from BEA concluded, that it was impossible for the crew to react on this hint.
"Would you really be smarter than ELACs/FACs that outwoted the truthsaying AoA probe in favor of other two that agreed, yet their output, while valid, had no semblance to actual AoA?"
The computer may not be able to 'decide' which values might be correct, but there could easily be an oral /visual warning, that there is a disagreement within the three AoA probes.
"CHECK GW was subtle hint that something was wrong, yet it wasn't picked up by the crew"
The German BFU has commented on this displayed message in Appendix 18 of the report and even the response from BEA concluded, that it was impossible for the crew to react on this hint.