Airbus crash/training flight
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It isn't about whether the AOA's were faulty because they weren't. No fault nothing to detect. Something external to the sensor affected them.
This is why accident investigation must encompass more than the flying aspect.
The aircraft had been painted and washed. This involves following strict procedures for good reason. You can affect sensors in an unpredictable way.
Just as pilots have procedures which must be adhered to so does everyone else.
The aircraft departed and for quite a bit of the flight everything was fine, then something happened to 2 out of 3 AOA's. The AOA is an extremely reliable sensor so 2 behaving badly at the same time is unheard of. This needs investigating. It isn't about my input is more worthy than yours, its about finding out what happened here and what happened involves more than just flight crew.
Something was technically wrong with that aircraft, we need to know what and why otherwise it will happen again.
This is why accident investigation must encompass more than the flying aspect.
The aircraft had been painted and washed. This involves following strict procedures for good reason. You can affect sensors in an unpredictable way.
Just as pilots have procedures which must be adhered to so does everyone else.
The aircraft departed and for quite a bit of the flight everything was fine, then something happened to 2 out of 3 AOA's. The AOA is an extremely reliable sensor so 2 behaving badly at the same time is unheard of. This needs investigating. It isn't about my input is more worthy than yours, its about finding out what happened here and what happened involves more than just flight crew.
Something was technically wrong with that aircraft, we need to know what and why otherwise it will happen again.
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And while i'm at it DW, the simple facts of the matter were that in the final seconds of the flight, while the captain had the side stick in the full nose up position the elevators were full nose down. This may have been a result of summation (in that the stabiliser was full nose up) who cares? If a pilot is ordering full nose up on the elevators, shouldn't he get it?
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Absolutely, SC, hence my #1169. I must be remembered, however, that once all the designers and engineers are done, and something is wrong with what they have done, that we have, for the foreseeable future at least, one human there who SHOULD be able to do some old fashioned flying (that is without software) and save the a/c and lives.
Yes, if something prevents them doing that it must be investigated and designed/engineered out - see para a). I have yet to see any evidence that such existed, but the F/O's sidestick trace would be of interest to me - or have I missed it on the traces? On an AB, does the 'Captain's sidestick position' always represent that or the master stick position?
EDIT: Picking up on Scotty: I think from what I have learned the sidestick is a rate demand rather than a position demand? Hence if the nose-up stab effort (at 263kts) was producing at least the designed max pitch rate, the elevators would be in opposition? Whether the airframe would have withstood max elevator as well I do not know. The nose was pitching up fairly rapidly after all at impact
Once again we appear to have the excessive stab trim/pitch couple causing the major upset. Is it time this was eliminated in the software? Perhaps some over-rideable limit on trimming range? As we know this is certainly an area where crew training needs to change.
Yes, if something prevents them doing that it must be investigated and designed/engineered out - see para a). I have yet to see any evidence that such existed, but the F/O's sidestick trace would be of interest to me - or have I missed it on the traces? On an AB, does the 'Captain's sidestick position' always represent that or the master stick position?
EDIT: Picking up on Scotty: I think from what I have learned the sidestick is a rate demand rather than a position demand? Hence if the nose-up stab effort (at 263kts) was producing at least the designed max pitch rate, the elevators would be in opposition? Whether the airframe would have withstood max elevator as well I do not know. The nose was pitching up fairly rapidly after all at impact
Once again we appear to have the excessive stab trim/pitch couple causing the major upset. Is it time this was eliminated in the software? Perhaps some over-rideable limit on trimming range? As we know this is certainly an area where crew training needs to change.
Last edited by BOAC; 5th Jul 2010 at 08:03.
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BOAC,
For the pitch control, the flight law is a load factor demand law.
Most probably, for the final dive, the pitch demand was limited by the load factor protection.
This could be the reason the BEA was not interested in publishing the vertical acceleration graph.
... could be more fonded that we might think.
The F/O's sidestick trace would be of interest to me too.
Who thinks the F/O remained of ice in those extreme attitudes ...
Me being in his seat it would have been "dual input" all over the place, or at best "priority right" ... if I could stay cool enough.
For the pitch control, the flight law is a load factor demand law.
Most probably, for the final dive, the pitch demand was limited by the load factor protection.
This could be the reason the BEA was not interested in publishing the vertical acceleration graph.
Originally Posted by bearfoil
Rumour only: The aircraft "protected" itself into the Ocean. allegedly.
The F/O's sidestick trace would be of interest to me too.
Who thinks the F/O remained of ice in those extreme attitudes ...
Me being in his seat it would have been "dual input" all over the place, or at best "priority right" ... if I could stay cool enough.
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Thanks for the clarification, Conf. The emphasis has to be on how they got to 51 degrees nose down at 1620' (a real 'coffin corner!) and not what the controls did thereafter.
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You're right BOAC - I suppose 97°of bank might have something to do with it...
Re sidesticks - there is no "master", the inputs are summed algebraically unless one pilot presses and holds the "takeover pushbutton" (same as AP disconnect pb). You should be able to tell from the FDR trace whether there is a dual input in Direct Law (if the control positions don't accord with capt. sidestick position) - can't see one. But in Normal/Alternate Law I reckon you need the FDR info on dual input.
What interests me is the lack of CVR information in the BEA interim report once it all went wrong- I would like to know whether the crew said anything about:
a) being in Direct Law
b) moving the THS from fully nose-up
c) why they raised the gear
d) why they looked at ECAM HYD system.
I like to think the final report will tell us....
Re sidesticks - there is no "master", the inputs are summed algebraically unless one pilot presses and holds the "takeover pushbutton" (same as AP disconnect pb). You should be able to tell from the FDR trace whether there is a dual input in Direct Law (if the control positions don't accord with capt. sidestick position) - can't see one. But in Normal/Alternate Law I reckon you need the FDR info on dual input.
What interests me is the lack of CVR information in the BEA interim report once it all went wrong- I would like to know whether the crew said anything about:
a) being in Direct Law
b) moving the THS from fully nose-up
c) why they raised the gear
d) why they looked at ECAM HYD system.
I like to think the final report will tell us....
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Indeed , it proves two things - use of aileron on a stalled wing is not a good idea and the best way to drop the nose is to apply lots of bank.
I suspect the CVR is not 'pretty' and may therefore not reach the public domain.
Do you deduce that they deliberately 'looked' at the HYD page or is there some automatic call or could someone just have 'missed' on a selection? Likewise why the ENG page later?
I suspect the CVR is not 'pretty' and may therefore not reach the public domain.
Do you deduce that they deliberately 'looked' at the HYD page or is there some automatic call or could someone just have 'missed' on a selection? Likewise why the ENG page later?
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Originally Posted by BOAC
The emphasis has to be on how they got to 51 degrees nose down at 1620' (a real 'coffin corner!) and not what the controls did thereafter.
Now, 17 seconds earlier, the airplane was at 3800 feet in a 57 degrees nose up attitude and virtually no speed. The emphasis could be on how they got there first.
It is amazing to consider that for a full minute, that airplane was out of control before it finally crashed.
The most interesting part should be to analyze what role played those two frozen AoA sensors in this flight.
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This is still nice to understand why the elevators did the opposite to the sidestick ... s(?) request.
Regarding 'how they got where' the '57 up' is all part of the route to 51 down. I think we are all pretty convinced, are we not, that the '57 up' was power/pitch?
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Regarding 'how they got where' the '57 up' is all part of the route to 51 down. I think we are all pretty convinced, are we not, that the '57 up' was power/pitch?
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BOAC
Good question - no thoughts either way now, although my previous post assumes they selected it, it's just one of the events that the CVR might explain a little. The HYD key is next to the F/CTL key, but if that was the target I would expect it to appear almost immediately after the wrong selection was realised.
Re the survivabilty of 50°pitch, to me it all hinges on the THS - was it stuck or did they just not move it (Direct Law = Manual pitch trim)? With the trim in a more normal position and the a/c in Direct Law a recovery should have been possible - and they probably would not have reached that attitude and the resultant low speed in the first place.
Do you deduce that they deliberately 'looked' at the HYD page
Re the survivabilty of 50°pitch, to me it all hinges on the THS - was it stuck or did they just not move it (Direct Law = Manual pitch trim)? With the trim in a more normal position and the a/c in Direct Law a recovery should have been possible - and they probably would not have reached that attitude and the resultant low speed in the first place.
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In a Boeing with competent pilots this could not have happened. Once again I think automation took over and the pilots were along for the ride. They probably were trying to use the proper recovery but automation overrode their inputs. The pitchup was probably a result of too much thrust being generated at critical speed. The pilots on a Boeing would have reduced the power to control the pitch and recovered with little problem. Pilots know how to recover from low speed stick shaker situations. They also know how to not be (to) agressive with thrust until they can control pitch.
Last edited by p51guy; 9th Jul 2010 at 23:05.
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In a Boeing with competent pilots this could not have happened
Anyone on a public forum making such comments should first start off with "my experience on both types is............"
So P51 guy, were the pilots in the Cali accident competent?
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AI v BCA drivel
I feel the occurrences of multiple crashes over the years of AI aircraft during training/test flights point more towards a misunderstanding of the protections and automatic functions of the computerized flight control system rather than indicating a critical defect in design.
A deeper understanding of the FBW protections as they apply in complex degradation scenarios seems to be called for if we are to avoid future incidents and crashes.
The question "Why does it do that?" should never be a part of a crew's standard vernacular.
A deeper understanding of the FBW protections as they apply in complex degradation scenarios seems to be called for if we are to avoid future incidents and crashes.
The question "Why does it do that?" should never be a part of a crew's standard vernacular.
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Being competent doesn't mean you can't make a mistake. The Cali captain was considered quite competent but no one will deny they made a huge mistake that night. Being competent means you understand how to manage an aircraft properly and can demonstrate it. CFIT has been accomplished by quite a few crews considered competent.