Airbus crash/training flight
A quick query for the A320 experts - is manual THS operation available in all flight modes or only when auto-trim is disabled?
Incidentally, an elevator with sufficient authority to override pitch excursions at extreme stabilizer angles would need to be very large indeed and would make the aircraft very sensitive without some very clever stick force gradient!
Incidentally, an elevator with sufficient authority to override pitch excursions at extreme stabilizer angles would need to be very large indeed and would make the aircraft very sensitive without some very clever stick force gradient!
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is manual THS operation available in all flight modes or only when auto-trim is disabled?
Incidentally, an elevator with sufficient authority to override pitch excursions at extreme stabilizer angles would need to be very large indeed
Thanks for taking the time Dysag. I take it from that that there are no common components that could have caused both problems. Cheers.
I'm not sure about this though
because if this is as good as it sounds then 2 of 3 AOA sensors wouldn't have frozen at the exact same time.
Framer
I'm not sure about this though
but boxes 1 & 2, to make it simple, were designed by different teams and contain different components.
Framer
Thanks for the clarification. Presumably manual pitch trim overrides auto-trim?
This indeed makes the lack of THS movement all the more mysterious; was it frozen, being incorrectly commanded to the extreme pitch limit as a consequence of multiple AoA detection system failures - or did the crew simply make no attempt to use the manual pitch trim?
Perhaps the CVR will clarify this - does the FDR record manual pitch trim pilot inputs?
Regarding 'stuck' AoA sensors, it is unlikely that the sensors themselves would be made by different companies, even though the computer architecture might be. Thinks of it as 'same mouse, different computer' for a simile.
I've had faulty AoA sensors on another aircraft type; on one occasion we experienced stick-shaker at rotate, but on another occasion the stick pusher operated at 300 ft during a training flapless approach when the stall protection system falsly detected a rapid AoA increase, triggering stall protection way before the critical AoA would have been reached (as it is designed to do).
This indeed makes the lack of THS movement all the more mysterious; was it frozen, being incorrectly commanded to the extreme pitch limit as a consequence of multiple AoA detection system failures - or did the crew simply make no attempt to use the manual pitch trim?
Perhaps the CVR will clarify this - does the FDR record manual pitch trim pilot inputs?
Regarding 'stuck' AoA sensors, it is unlikely that the sensors themselves would be made by different companies, even though the computer architecture might be. Thinks of it as 'same mouse, different computer' for a simile.
I've had faulty AoA sensors on another aircraft type; on one occasion we experienced stick-shaker at rotate, but on another occasion the stick pusher operated at 300 ft during a training flapless approach when the stall protection system falsly detected a rapid AoA increase, triggering stall protection way before the critical AoA would have been reached (as it is designed to do).
Last edited by BEagle; 2nd Mar 2009 at 09:11.
The 737 QRH states "Elevator control is sufficient to safely land the airplane regardless of stabilizer position"
BEagle said,
Can I take it that when Boeing wrote that they were assuming the aircraft was constantly operated within normal pitch limits, and from what BEagle has said that all airliners currently in operation would be in a similar boat to the A320 with respect to unusual attitudes and extreme THS angles?
Framer
BEagle said,
Incidentally, an elevator with sufficient authority to override pitch excursions at extreme stabilizer angles would need to be very large indeed and would make the aircraft very sensitive without some very clever stick force gradient!
Framer
Last edited by framer; 2nd Mar 2009 at 09:02. Reason: to make it less confusing
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A bad batch of components does happen, albeit maybe not from new, but definitely after return to shop for fault rectification or modification. However, sensors contaminated with paint happens a lot more often.
Re. the Boeing 737 reference, was that extract taken from a 'jammed stabilizer' abnormal procedure?
Presumably there is an associated speed limit?
Presumably there is an associated speed limit?
BEagle it is from the STABILIZER TRIM INOPERATIVE checklist and there is no speed reference....Actually it is leading you down a path to a F15 landning so I guess that is a speed reference really.
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Appreciate the informative chat from TP on the phone (my AB AND social advisor
). Back to banging my 'drum' about 'training', except here I see more a mindset than a training issue.
We have an aeroplane that 'cannot stall' - not even the doorman can do it. It did and it appears the crew were taken unawares. At 45:12, ?stalled? we see a classic input of left stick on a stalled wing (Ab initio Stalling I exercise) producing the expected roll to the right (struggling with the FDR trace here on aileron position, incidentally - stick left, aileron left (red) up??). ?Is it possible for the FBW to reverse the aileron response or is the trace wrongly annotated - or was there an 'override'??
The danger, as we progress further into FBW and software is that we will lose the basic skills of handling. The system is fantastic - in normal use - but has apparent serious flaws in the abnormal.
Now, back to the CAS query from my post (currently 907). I believe Lemurian replied assuring me that those readings were false and due to 'unusual manoeuvres. His reply has been lost in the body count. I SUSPECT I probably have more experience of 'unusual manoueuvres' in swept wing a/c than he, and have NEVER seen that size of CAS fluctuation, not even with a wing mounted pitot and certainly not with a c/l set. Also I see only an increasing pitch (admittedly 'extreme') and changes in in roll. I am becoming convinced that several bits of the system were not telling the truth here, which renders the 'Titanic' principle worthless. Anyone else expect to see 3x200kt speed excursions in 10 seconds in those manoevres?
EDITED to say I've realised I misread the aileron traces -doh!
). Back to banging my 'drum' about 'training', except here I see more a mindset than a training issue.We have an aeroplane that 'cannot stall' - not even the doorman can do it. It did and it appears the crew were taken unawares. At 45:12, ?stalled? we see a classic input of left stick on a stalled wing (Ab initio Stalling I exercise) producing the expected roll to the right (struggling with the FDR trace here on aileron position, incidentally - stick left, aileron left (red) up??). ?Is it possible for the FBW to reverse the aileron response or is the trace wrongly annotated - or was there an 'override'??
The danger, as we progress further into FBW and software is that we will lose the basic skills of handling. The system is fantastic - in normal use - but has apparent serious flaws in the abnormal.
Now, back to the CAS query from my post (currently 907). I believe Lemurian replied assuring me that those readings were false and due to 'unusual manoeuvres. His reply has been lost in the body count. I SUSPECT I probably have more experience of 'unusual manoueuvres' in swept wing a/c than he, and have NEVER seen that size of CAS fluctuation, not even with a wing mounted pitot and certainly not with a c/l set. Also I see only an increasing pitch (admittedly 'extreme') and changes in in roll. I am becoming convinced that several bits of the system were not telling the truth here, which renders the 'Titanic' principle worthless. Anyone else expect to see 3x200kt speed excursions in 10 seconds in those manoevres?
EDITED to say I've realised I misread the aileron traces -doh!
Last edited by BOAC; 2nd Mar 2009 at 13:01.
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BOAC
Good to see you are finally reading the report! Re the CAS the report states:
CAS invalid below 40 kt. I can't explain the spikes but I'll bet Sir Fred's pension that the actual a/c airspeed did not follow the graph!
Re that aileron trace: would have been much easier upside down!
Red - left aileron - up on the trace = down on the wing, blue - left aileron goes the other way. No reversal, logical because the roll control is Direct throughout from 15:45:15.
Training - on type rating training I am always very careful about stalling and direct law handling, there is a fair amount in the course.. but it was probably that doorman who wrote in the FCTM, and I quote...
They might just ask him to rewrite that bit...
TP
Good to see you are finally reading the report! Re the CAS the report states:
At 15 h 45 min 42 s, the speed parameter recorded became invalid.
At 15 h 45 min 53 s, the pitch reached 7° nose down. The recorded speed became valid again at 46 kt.
At 15 h 45 min 53 s, the pitch reached 7° nose down. The recorded speed became valid again at 46 kt.
Re that aileron trace: would have been much easier upside down!
Red - left aileron - up on the trace = down on the wing, blue - left aileron goes the other way. No reversal, logical because the roll control is Direct throughout from 15:45:15.
Training - on type rating training I am always very careful about stalling and direct law handling, there is a fair amount in the course.. but it was probably that doorman who wrote in the FCTM, and I quote...
The effectiveness of fly-by-wire architecture, and the existence of control laws, eliminate the need for upset recovery maneuvers to be trained on protected Airbus aircraft.
TP
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BOAC
What I wrote was that these readings are in all probability the result of the pitot/static sensors being in a vastly disturbed airflow...nothing more and nothing less...Could we call them "transients" ?
As for our respective experiences...as the Arabs say : Maalesh ! At least over you I have the advantage as both the 737 and the 320 are among my ratings.
But you're right, I've never ever flown any of my jets in (as opposed to into ) a stall...old and not bold, alas !
Beagle
Yes, man trim overrides auto-trim.
As for the un-moved THS, yes we need more data...
I believe Lemurian replied assuring me that those readings were false and due to 'unusual manoeuvres. His reply has been lost in the body count. I SUSPECT I probably have more experience of 'unusual manoueuvres' in swept wing a/c than he, and have NEVER seen that size of CAS fluctuation, not even with a wing mounted pitot and certainly not with a c/l set.
As for our respective experiences...as the Arabs say : Maalesh ! At least over you I have the advantage as both the 737 and the 320 are among my ratings.
But you're right, I've never ever flown any of my jets in (as opposed to into ) a stall...old and not bold, alas !
Beagle
Presumably manual pitch trim overrides auto-trim?
This indeed makes the lack of THS movement all the more mysterious; was it frozen, being incorrectly commanded to the extreme pitch limit as a consequence of multiple AoA detection system failures - or did the crew simply make no attempt to use the manual pitch trim?
This indeed makes the lack of THS movement all the more mysterious; was it frozen, being incorrectly commanded to the extreme pitch limit as a consequence of multiple AoA detection system failures - or did the crew simply make no attempt to use the manual pitch trim?
As for the un-moved THS, yes we need more data...
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Additionally, since the data is CAS and downstream of processing by the ADCs, it is possible [speculation] that the data are erroneous due to inappropriate corrections being applied/extrapolated outside the expected range of sensor operation.
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Spikes in CAS graph are due to sloppy plotting
Since the report says that CAS data between 15:45:42 and 15:45:53 was "NCD" (no computed data), another name for "invalid" data, there was no value that could justifiably have been plotted. The values that we see are artifacts, and have no relation to the actual air speed.
Connecting lines should not have been drawn, and arguably even the invalid data points should not have been plotted. They have no significance whatsoever.
In fact such lines should never be drawn, unless the expected rate-of-change is so low that linear interpolation will provide a sufficient approximation.
Bernd
Connecting lines should not have been drawn, and arguably even the invalid data points should not have been plotted. They have no significance whatsoever.
In fact such lines should never be drawn, unless the expected rate-of-change is so low that linear interpolation will provide a sufficient approximation.
Bernd
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Smack on the wrist from teacher - I have amended my interpretation of the aileron traces.
I had assumed the CAS was 'invalid' only due to going below its lower limit.
Yes, TP - it is time for the AB folk to acknowledge the need for upset recovery.
......and MFS - that last paragraph popped my CB
If the guys in the cockpit were getting the same CAS readings........................
Since the AoA vanes APPEAR to have behaved normally for the first part of the flight, can anyone tell if they were being properly heated or are we looking at an insidious icing problem rather than the 'painting' issue which might just be no more than a valid 'cautionary warning'?
I had assumed the CAS was 'invalid' only due to going below its lower limit.Yes, TP - it is time for the AB folk to acknowledge the need for upset recovery.
......and MFS - that last paragraph popped my CB
If the guys in the cockpit were getting the same CAS readings........................
Since the AoA vanes APPEAR to have behaved normally for the first part of the flight, can anyone tell if they were being properly heated or are we looking at an insidious icing problem rather than the 'painting' issue which might just be no more than a valid 'cautionary warning'?
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PJ2, your last post was interesting ... but it disappeared (?)
I read you 5/5 TP, and that's why I do ask the BEA :
Where is the load factor graph ???
From time 15 45 57 the elevators were in the amazing full down position when the Capt (We don't know for the FO ...) was actually pulling on its side stick.
As the speed was building up, I suspect the elevators were just trying to counteract the increasing effect of the inappropriate THS position, and so in order to respect the load factor limitation ...
That Airbus is a really complex machine .............
For Safety Concerns,
AeroPeru and Birgenair were both at night time with no external visual reference.
Originally Posted by TyroPicard
I probably should have said "may" not "will". In pitch load factor demand law (Normal,Alternate) the sidestick and elevator positions are not directly connected. If you fly stick neutral the ELAC moves the elevator to maintain 1g. Imagine a jammed THS and change the thrust/speed/config, if stick neutral the elevator will move to maintain 1g - invisible to the pilot unless you display F/CTL system on ECAM.
Without the F/O sidestick readout, the actual load factor demanded and achieved, it is impossible to be certain why the elevator is in that position. Hope that's clearer.
Regards, TP
Without the F/O sidestick readout, the actual load factor demanded and achieved, it is impossible to be certain why the elevator is in that position. Hope that's clearer.
Regards, TP
Where is the load factor graph ???
From time 15 45 57 the elevators were in the amazing full down position when the Capt (We don't know for the FO ...) was actually pulling on its side stick.
As the speed was building up, I suspect the elevators were just trying to counteract the increasing effect of the inappropriate THS position, and so in order to respect the load factor limitation ...
That Airbus is a really complex machine .............
For Safety Concerns,
AeroPeru and Birgenair were both at night time with no external visual reference.
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A320 Probe Heat
One pushbutton (pb) on the overhead panel controls all probe (pitot, AOA, TAT) and window heat, static ports. Normally in AUTO - the AOA probes would have been heated when one engine running or a/c in flight. Can be selected ON - all heat then on. There is no off selection possible it's either AUTO or ON.
There are three independent Probe Heat Computers (PHC) which control and monitor, and provide warnings for each individual sensor. They are grouped into CAPT,F/O, and STBY probes - so a heating failure/overheat to two AOA probes would show as two ECAM warnings provide by two PHC's.
There is no mention of ECAM warnings in the report.
CONF
Do you think the BEA would have mentioned Dual Input on the sidesticks? It is very relevant to any AB FBW event.
TP
There are three independent Probe Heat Computers (PHC) which control and monitor, and provide warnings for each individual sensor. They are grouped into CAPT,F/O, and STBY probes - so a heating failure/overheat to two AOA probes would show as two ECAM warnings provide by two PHC's.
There is no mention of ECAM warnings in the report.
CONF
Do you think the BEA would have mentioned Dual Input on the sidesticks? It is very relevant to any AB FBW event.
TP
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Do you think the BEA would have mentioned Dual Input on the sidesticks? It is very relevant to any AB FBW event
- Is my Captain suddenly incapacitated ?
- Is my Capt in a bad day ?
- Is its sidestick suddenly u/s ?
- Is it anything else ?
- Should I intervene ?
I personally don't think I would have had the nerves to remain in the stand by mode ...
The FO Side Stick Position is not number 1 on my most wanted parameters list but as the BEA already gave us not less than 40 parameters showing absolutely no kind of status change ... why not ?
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CONF iture -
I asked this once but was criticized for doing so by some "expert" here. Not knowing about FBW or Airbus aircraft, I asked if there was any kind of 'priority' in the side sticks. You mentioned 'incapacitation' as an example. If one pilot has his body weight against one side stick, and the other pilot attempts to move his, what happens?
I asked this once but was criticized for doing so by some "expert" here. Not knowing about FBW or Airbus aircraft, I asked if there was any kind of 'priority' in the side sticks. You mentioned 'incapacitation' as an example. If one pilot has his body weight against one side stick, and the other pilot attempts to move his, what happens?
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framer:
The 737 QRH states "Elevator control is sufficient to safely land the airplane regardless of stabilizer position"
The 737 QRH states "Elevator control is sufficient to safely land the airplane regardless of stabilizer position"
That correlates to my experiences in the SIM.
My factory AI manuals do not make any mention of the fact that a HS trimmed full stop cannot be controlled by elevator. Neither was that covered during my training.