AF 447 Thread No. 12

[Concours77]

"...The difference between the crash and a crew who knows what's going on and how to deal with the situation more elegantly..." ....pretty arrogant.

Were each of these aircraft equipped with "..we have no indications..." panels?

No record exists of what the instrument panels were displaying in 447....

Alot taken for granted, at crew's expense herein...

[Turbine D]

Concours77,
No record exists of what the instrument panels were displaying in 447....
So tell me, how do you know "we have no indications..." panels? You are misinterpreting a verbal statement about speed to fit your theory of instrument panels...

Why do you think it took so much attention and time to get the roll stopped? What do you think made the situation, once in the stall at 38K feet, not recoverable besides not recognizing they weren't in a stall?

Which memory item did the PF potentially revert to when he recognized they were out of the flight path?
pretty arrogant
Not so much so when you try to explain what needs to be done to stay safe...

[Concours77]

"Which memory item did the PF potentially revert to when he recognized they were out of the flight path"

Approach to stall at low altitude. What flight path? No FDs. No "indications"

You know exactly what flight path, you have the passive recordings of their four minutes of wandering. You have this knowledge. You presume to judge them because they did not?

[_Phoenix]

I do not recall discussions about stall warning triggered at 2 h 10 min 51. The first long/consecutive (not sporadic) stall warning. At that point in time, the “situation” was fully recoverable. Why didn’t happened? I think it’s interesting to see why Bonin wasn’t able recognize, or more precisely, he didn’t believed in the stall situation. It was discussed only that he was an Airbus pilot. He was accustomed to sporadic/false stall warnings, kind of immune to that specific sound. Airbus cannot be stalled in normal law, then most of the times the sporadic stall sound was inhibited automatically. No alert, no worries. But he was an experienced glider pilot. For sure he experienced the real stall condition in a glider, maybe only in a glider. The glider behaviour is completely different. You can feel the approaching of stall, clear buffet, no aerodynamic noise and 0 g. Then the nose drops abruptly towards the ground, the speed and aerodynamic noise increase very rapidly and you have to pull the stick sharply before reaching the overspeed threshold. None of these known “stall symptoms” accompanied the stall warning of AF447. No buffet, vertical acceleration ~1g and for subsequent 20 seconds the variometer indicated climb, that’s quite impossible, at least according to aerodynamic stall definition of any manual. Finally after 20 seconds (while thrust was at TOGA) variometer changed sign, it went abruptly into negative accompanied by a huge aerodynamic noise generated by the airflow around the A330 body. “I don’t have control
of the airplane at all” “I have the impression (we have) a crazy speed”
About this aspect, I’m saying that was not detailed before, the stall warning triggered when not suppose to. Also I believe this “false” stall warning is related to the following statement in the report
the threshold of the stall warning varies with the Mach, in such a way that it is triggered - in alternate or direct law – before the appearance of buffet.
About the other swisscheese hole (of the stall warning ceased for speed <60kts) , it was perfectly aligned with the Captain entering the cockpit. Then, the last chance of a fresh acknowledgment of the situation was obliterated.

[Concours77]

Is buffet associated with Stall possible in Normal Law? Would it matter? FA: "...should we sit?..." (Belt in) "Yes I think so...'

Captain entering cockpit was climbing an aisle at 15 degrees nose up? 1g? He said nothing except "Er... what are you doing?"

With aerodynamic noise at high level, and an arduous "climb" up the aisle, he misses the cues?

[Turbine D]

"Which memory item did the PF potentially revert to when he recognized they were out of the flight path"
The two copilots had only been trained for the emergency maneuver at lower levels, in the course of which the pitch attitude to adopt is 10° or 15°.
Is buffet associated with Stall possible in Normal Law?
No, not on the Airbus aircraft.
I do not recall discussions about stall warning triggered at 2 h 10 min 51.
That is correct. From the CVR:
2h10min51,4 SV : Stall
2h10min52,0 SV : Stall
Neither of the pilots made any reference to the stall warning, neither of the pilots formally identified the stall situation.

When the Captain entered the cockpit, he stood behind but between the two pilots while he quickly scanned the situation. He got only general verbal information from the PF & PNF, so he had few clues to go by, including the position of the side stick of the PF. The one thing he did have a good view of was the trim wheels position. Normally they bounce around a little but the THS had moved to the full up position responding to the trim system and stabilizing the aircraft in the pitch axis. There was quite a bit of detailed discussion in previous Threads about the aerodynamics of the situation AF447 was in and the effectiveness of the elevators at that point. Throughout the flight, the movements of the elevator and the THS were consistent with the pilot’s inputs.

The biggest clue given to the Captain came too late: 2 h 13 min 40
PF - "But I’ve been at maxi nose-up for a while."
Captain - "No no no don’t climb."
PNF - "So go down."

[Concours77]

The icing event lasted 60 seconds. Ninety seconds after the Master Warning/Cavalrty Charge, the Captain came back to the flight deck. At that point, the aircraft was at its assigned altitude, the Angle of attack was forty degrees, and they were descending, rapidly.

"...What the Hell are you doing?..." So, Captain noticed the loss of control. erm, boy howdy.

There was no angle of attack indicator, and Captain evidently neglected to ascertain Bonin"s stick aft, to the stop.

A minute later, they were discussing whether they were Descending, or Ascending.

Three issues of design prevented them from recovery.

No angle of attack indicator.

No way to see stick inputs from PF.

This aircraft Stalls essentially without cues, it is benign in the STALL.

Return one of these deficiencies to the cockpit, and they do not crash.
Return two of them, and they do not STALL.

Return all three, and we would have nothing to write about.

And Air France would be out forty thousand dollars for the AoA instrument.

C'est la Vie.....



.

[KayPam]

Again, the stick inputs from the PF are very easy to see if you just look at them.
You would see that immediately if you sat in an airbus pilot seat.

I agree with you on the necessity for a smart aoa indicator. As well as a stick shaker if the airbus does happen to stall.

[Turbine D]

Concours77,
This aircraft Stalls essentially without cues, it is benign in the STALL.

Return one of these deficiencies to the cockpit, and they do not crash.
Return two of them, and they do not STALL.

Return all three, and we would have nothing to write about.

And Air France would be out forty thousand dollars for the AoA instrument.

C'est la Vie.....

Problem solved, no need for further discussions... ;)

[_Phoenix]

Neither of the pilots made any reference to the stall warning, neither of the pilots formally identified the stall situation.
They hadn’t time for a narrative in the CVR, the actions and the communications between them are enough proof.
The proof is all there: the THR levers were advanced to TOGA, two seconds after “Stall, Stall” (at 2h 10min 51). 7 seconds later PF confirmed TOGA power achieved, PNF advise for gentle maneuvers on lateral, then later both are perplex: “But we’ve got all the engines, what’s happening?”
Important remark: During this particular sequence, there was not any physical stall situation for the aircraft, only the false stall warning. This I’m trying to explain in my last two posts, here.

[Concours77]

Bonin initiates his first singular (unlinked in mayonnaise) Nose Down before the STALLWARN. 2:10:09.

Can you confirm that TOGA is an appropriate selection? With a full NOSE UP THS, and full thrust on engines also producing Pitch Up, how is aero flight regained? (2:10:51)

So, absent any STALL airframe response, why would they initiate a STALL "recovery"?
At the very least, keeping aft stick throughout is not consistent with STALL recovery, only a trained response to STALLWARN approach to land? That includes Added Thrust?

How is full thrust appropriate for recovery? Wouldn't NOSE DOWN and reduced Thrust be the drill? They were worried about crazy speed? They had gobs of altitude to work with?

[Concours77]

Again, the stick inputs from the PF are very easy to see if you just look at them.
You would see that immediately if you sat in an airbus pilot seat.

I agree with you on the necessity for a smart aoa indicator. As well as a stick shaker if the airbus does happen to stall.

The Captain was between the two pilots, and behind. No visibility of Starboard stick for him. We have no evidence of PNF peeping the PF stick....

AoA. How difficult and expensive can it be to display a computed AoA parasite from the computer?

"...ERM, FORTY DEGREES AoA....!?!!...Push the Nose Down, EH?"

Airbus was granted a waiver for no pusher/shaker at certification... They had convinced the authority that the a/c would not Stall in Normal Law, and in ALTERNATE, the pilots would be ready for STALL, no passive safety device would be necessary?

Additional design deficiencies.

1. Automatic Pitch Trim Nose UP into the STALL.

2. Absence of alerting device to signify Auto TRIM into STALL.

2a. Cumbersome manipulation of TRIM by hand, to return TRIM to neutral. Once released, the TRIM moves to regain full Nose UP. Extremely inconvenient in an emergency. Enforced distraction.

3. Surprise handling change in ROLL, splitting the stick into two modes.

4. Back up Speed System not installed, optional.

5. Low Energy Alerting Program not installed, not available.

6. Slow rolling replacements of deficient speed sensors, Pitots.

Having read and reread the endless focus on PF's stubborn NOSE UP, I am including the aircraft deficiencies, in the interest of justice.

[Turbine D]

Concours77,
Can you confirm that TOGA is an appropriate selection?
It is not the correct selection at high altitudes, it is the correct selection if a stall warning is received right after TO. As I mentioned previously, I believe the pilots recalled the memory list, but not all of it, especially the part they needed to recall:
http://i1166.photobucket.com/albums/q609/DaveK72/i-GnmPntp-L.jpg (http://s1166.photobucket.com/user/DaveK72/media/i-GnmPntp-L.jpg.html)
Actually, the safe conduct of the flight wasn't impacted and all the pilots needed to do was level the wings, set the thrust to 80% of N1, and set the pitch to 2.5 - 3.0 degrees. Then begin to troubleshoot using the messages received and written documentation.
Here is a listing of other flights that experienced what AF447 experienced, twelve received stall warnings:
http://i1166.photobucket.com/albums/q609/DaveK72/UASEvents.png (http://s1166.photobucket.com/user/DaveK72/media/UASEvents.png.html)
All survived. For AF447, they are cruising along normally, engines are providing appropriate thrust, pitch is within limits, slight turbulence and then the AP and AT disconnects and the message word is speed. What could cause it to be a problem?

I think you are concentrating on items that happened as a result of not following instructions. Why didn't the pilots follow instructions they were trained to react to and follow? Why didn't the pilots remember the pitch/thrust item for the altitude they were initially at? I recall Air France had put out a written document as a result of ice clogged pitots, making the problem known to pilots and what to do if encountered. I am not sure the AF447 crew received the document or not before the incident.

[Concours77]

They hadn’t time for a narrative in the CVR, the actions and the communications between them are enough proof.
The proof is all there: the THR levers were advanced to TOGA, two seconds after “Stall, Stall” (at 2h 10min 51). 7 seconds later PF confirmed TOGA power achieved, PNF advise for gentle maneuvers on lateral, then later both are perplex: “But we’ve got all the engines, what’s happening?”
Important remark: During this particular sequence, there was not any physical stall situation for the aircraft, only the false stall warning. This I’m trying to explain in my last two posts, here.

Hi Turbine,

This post prompted my response. Actions taken without communication are not appropriate, if not trained or listed in the QRH.

I'd have to check, but "What's happening....?" the aircraft is climbing wildly? So, why the hyperfocus on power? If descending, with positive Pitch, there is no Stall, at least not a traditional one.

I believe the pilots were never aware of STALL, including the Captain, and this due to the Airbus' unique flight characteristics in full STALL. The aircraft, even in descent at 10,000 fpm was controllable, pedestrian attitude (high Pitch excluded). None of the pilots insisted on ND. The only command related to PITCH was Robert: "...climb,climb,climb....!" then, Captain: "...No,No,No, don't climb..."

Even after it was discovered Bonin had held aft stick, there was no acknowledgment of STALL.

May we eliminate reference to Bonin's glider time? It was unhelpful at best, since the A330 in this instance gave not one single aerodynamic clue of Stall. The "buffet" claimed in the report was unnoticed or unremarkable, since they had been in turbulence, sufficient to direct CC to "buckle up'.....

[Vessbot]

One item I haven't seen in all these discussions is the flight directors. The report says that they disappeared along with the autopilot disconnection, and then reappeared and disappeared several times again. Crucially, the first time it reappeared it commanded 6000 fpm up, and the remaining times 1400 fpm up. Given the general FD overdependance talked about often on these forums, combined with the tunnel vision and stimulus-ignoring that happens during task saturation, this supplies a very big and easy puzzle to the "inexplicable" issue of why the PF kept pulling up.

I read this a while ago, and wondered why the FD would command this without being told to by the pilots. Just now I went back into the report, and that question is answered in section 1.6.9.2, which says that if they were not turned off manually, and reappear automatically when the computer data becomes valid again, they come back in HDG and VS modes. I'm sure this is common knowledge among Airbus pilots, which I am not. I can only assume that the VS value commanded is that which is what the airplane is doing the moment when they reappear.

So, if the plane was momentarily combing at 6000 fpm in a totally unsustainable zoom climb, it'll keep guiding the pilot to that climb regardless of the plane's ability to do that. And if the wide-eyed and overloaded pilot reduced his ability to observe (and interpret) all the pertinent display values, and reverted to trained habit (following the FD) then there's the recipe for the disaster that happened.

On learning this, I immediately thought that this is a terrible design wrt. human factors. The FDs, if off, should not come on again without their mode being explicitly set by the crew, according to what parameter the crew wants the FD to guide them to. Here, the "lock in the present VS" premise obviously failed the crew, who I'm sure were not aware of (much less in desire of) what they were following. Airbus pilots, has this been changed? What is the current behavior of the system in this case?

[Uplinker]

Again, the stick inputs from the PF are very easy to see if you just look at them.
You would see that immediately if you sat in an airbus pilot seat.

...............As well as a stick shaker if the airbus does happen to stall.

Not necessarily. At night and if the cockpit is dark, it is not so easy to see - especially if the tray table is out. Also, if you are expecting a pilot not to hold full back-stick, (why would he?), you would not look for it. This is why, in my opinion, the real cause of the problem was so baffling to the other F/O and the Captain. Neither of them expected that Bonin would be holding full back-stick, so they did not even look for it.

Linked controls and/or some sort of side-stick position indicator on the PFD would have alerted the crew to Bonins' actions.

Another thing that troubles me is that this scenario is not being demonstrated in the SIM. I had it 'done' to me in the SIM by a very good TRE, and it opened my eyes. It is all very well doing a few minutes of high level manual handling and a few more minutes of low level stall training, but not the same thing as actually experiencing what these poor chaps had.

[EMIT]

Vessbot

All aircraft, not just Airbus, will have Flight Directors and Autopilots that, by default, initiate in HEADING HOLD and (present) VERTICAL SPEED. Those modes are the only ones that can start from scratch (meaning present conditions).
All other modes need certain parameters to be established ALREADY to continue the guidance along that condition.

Concours77
You are misinterpreting non-sensical exclamations by the AF447 crew as technical realities.
That crew talked about "the screens being crazy" - that is a very unprofessional observation for pilots. Those "screens" are displays that portray a multitude of information from many different, independent sources.
True, the speed indication was weird for a short while, the altitude indication dipped a bit at the very beginning, but the ATTITUDE INDICATION, that is THE MOST IMPORTANT CONTROL INSTRUMENT in INSTRUMENT FLYING, was indicating with perfect precision what was happening.
A transport aircraft at cruise altitude is flown with the nose about 3 degrees above the horizon, for a climb a maximum of 1 degree higher, for a descent about 1 degree lower, for an idle descent about on the horizon, but NEVER, NEVER NEVER at 15 degrees above the horizon.
The communication between the co-pilots was all about CLIMBING or GOING DOWN, but NEVER ABOUT THE PITCH ATTITUDE that was required.
Note, that by zooming up untill all speed was bled off, the climb automatically was turned into a descent (GO DOWN), but the way in which they went down was not a wise one.
The captain had the bad luck to enter the flight deck just as the ALTITUDE was about 35.000 ft again, just the same value as when he had left the flight deck, so he had completely missed the zoom climb and the susequent drop down. The co-pilots could tell him nothing useful, so it took a while for him to figure out wat the rapidly decreasing altitude indication really meant.

Please note that failures of display screens are also monitored situations, monitored by ECAM that is, and the flight data showed no abnormality at all in that respect.
Note that I have used capital letters to write things like ATTITUDE, because people do often, in postings, confuse the word with an L and a T with the version with double T, and that is quite a crucial difference for a pilot flying on instruments.

[Turbine D]

Vessbot,
One item I haven't seen in all these discussions is the flight directors. The report says that they disappeared along with the autopilot disconnection, and then reappeared and disappeared several times again.
The appropriate question is, why didn't they turn them both off? The reason why they should be off is because they are being fed erroneous data that the pilots should not respond to.

Air France A330/A340 Abnormal Procedures

“Unreliable IAS” in force at the time of the accident

PF AP..........................OFF
CP FD1 and 2................OFF
PF A/THR......................OFF
PF Set Thrust................CLB
PF Set Pitch..................5º

[Vessbot]

Vessbot

All aircraft, not just Airbus, will have Flight Directors and Autopilots that, by default, initiate in HEADING HOLD and (present) VERTICAL SPEED. Those modes are the only ones that can start from scratch (meaning present conditions).
All other modes need certain parameters to be established ALREADY to continue the guidance along that condition.


What I'm saying is that if turned off automatically for whatever reason (such as invalid air data in this case), it should stay off until manually set. Do you see the problem with coming on commanding VS 6.0 at the performance ceiling of the plane?

[Goldenrivett]

Originally Posted by Vessbot
it should stay off until manually set


That was the BEA recommendation in 2012.

See Page 210. https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf
4.3.7 Ergonomics
The crew did not de-activate the flight directors and did not call out any changes in
FMA mode. It is not sure that they noticed the appearances and disappearances of the
flight director crossbars. It is likely that the crew did not know of the mode changes
when the flight director became active again, reading and assimilating the displays on the FMA in dynamic and stressful conditions not being instinctive or natural.
It seems that requiring an action from the crew to re-engage this automatic system
would, on the one hand, lead to a consistency with the autopilot and the autothrust,
and on the other hand stimulate a check on the modes and the consistency of the
commands presented at the time of the re-engagement.
Consequently, the BEA recommends that:
€ EASA require a review of the re-display and reconnection logic of
the flight directors after their disappearance, in particular to review
the conditions in which an action by the crew would be necessary to
re-engage them; [Recommendation FRAN-2012-047]
Further, even if it is not sure that the crew followed the orders from the flight director
while the stall warning was active, the orders from the crossbars were in contradiction
with the inputs to make in this situation and thus may have troubled the crew.
Consequently, the BEA recommends that:
€ EASA require a review of the functional or display logic of the flight
director so that it disappears or presents appropriate orders when the
stall warning is triggered. [Recommendation FRAN-2012-048]

[EMIT]

What I'm saying is that if turned off automatically for whatever reason (such as invalid air data in this case), it should stay off until manually set. Do you see the problem with coming on commanding VS 6.0 at the performance ceiling of the plane?

The problem that I see is in regarding the Flight Director as a COMMAND (as in a command that has to be followed blindly).
I command the aircraft to go where I want it to go, and if I have properly managed my autoflight system, that system will suggest attitudes to me that will be pretty close to, and possibly a refinement of, what I am already doing.

Any other approach to flight guidance is rubbish.

[Vessbot]

The problem that I see is in regarding the Flight Director as a COMMAND (as in a command that has to be followed blindly).
I command the aircraft to go where I want it to go, and if I have properly managed my autoflight system, that system will suggest attitudes to me that will be pretty close to, and possibly a refinement of, what I am already doing.

Any other approach to flight guidance is rubbish.

1. You're substituting your desire for how the FD should be followed, for the reality of how it is in far too many cases (including, almost certainly, this one).

2. With any level of intensity of following the FD, ranging from blind slavishness to skeptical dismissal in favor of the raw data behind it, is there any benefit to it coming on at VS 6.0 over staying off? If yes, what is it?

[Concours77]

EMIT:
"True, the speed indication was weird for a short while, the altitude indication dipped a bit at the very beginning, but the ATTITUDE INDICATION, that is THE MOST IMPORTANT CONTROL INSTRUMENT in INSTRUMENT FLYING, was indicating with perfect precision what was happening."

The speeds were lost for sixty seconds. ATTITUDE? How would you know? From the report? PF PFD was not recorded, and he was flying. "We have NO INDICATIONS..." Until that comment is understood, making statements about panel are not reliable.

I think PF was relying on his FD, which was int. I also believe, and from early on, believed his inputs were mimics of what he saw on FD.

Without CVR data about PITCH discussions, we rely on the results of same. It is likely this was done because it is rude to point out what a fellow pilot is doing with his stick, rather the result can be discussed.... culture.

At Captain's re entrance, he had just clambered up a deck that was at fifteen degrees inclined Nose Up. A check for your "explicit ATTITUDE data" would have informed him they were PITCH/in the WEEDS.

"...Note, that by zooming up untill all speed was bled off, the climb automatically was turned into a descent (GO DOWN), but the way in which they went down was not a wise one..."

The beginning of descent could not have been associated with STALL. They transitioned from ascent to descent with no appreciable change in ATTITUDE?

Having no discernible aero cues to show STALL, PF assumed instead they had started accelerating. With PITCH at ten degrees, that must have been very confusing....

He became obsessed with noise, and a descent that made no sense. The other two did not ever consider STALL

If as you say the ATTITUDE was accurate, and should be employed in flight, you have isolated a disturbing circumstance where the Airplane was reinforcing there was no STALL, and arresting descent should be done by commanding NOSE UP....instead of a workable plan to regain aerodynamic flight....no?

[Vessbot]

You're not reading him right. His first sentence is "The problem that I see is in [what the problem is]"

[Concours77]

Apologies. I thought you were promoting the Use of the FD in their situation?
There is a way to compute AoA with the FD? Also, do you think he may have been trying to project the Flight Path Vector for some help?

[Vessbot]

You deleted the post you're apologizing over, so now mine looks like nonsense to those who didn't read yours.

[_Phoenix]

So, if the plane was momentarily combing at 6000 fpm in a totally unsustainable zoom climb, it'll keep guiding the pilot to that climb regardless of the plane's ability to do that. And if the wide-eyed and overloaded pilot reduced his ability to observe (and interpret) all the pertinent display values, and reverted to trained habit (following the FD) then there's the recipe for the disaster that happened.
I think this is the only rational explication for the zoom climb, PF was following the FD cross bars.
Also, maybe the seat was not properly adjusted, at the moment of AP disconnect. The arm rest was recovered in the up position. In the simulation below, the perceived neutral position of the sidestick seems to be at 2/3 of the total travel, instead of 1/2, visible in several occasions, where the lateral input goes from full left to full right and reverse.

The FD indication was exactly as per PF preference expressed (earlier in CVR), to climb above the weather.
The stall warning was disregarded since it was in conflict with two indications. FD -> climb and variometer showed steady climb of 1000-2000 ft/min (a stalled wing doesn't sustain prolong climb).

That fast they got into coffin corner with THS at max NoseUp. At that point they had 3 puzzles to solve:
1 - to recognize the deep stall and the aerodynamic noise of the vertical fall.
2 - to recognize the excessive AOA and THS at max NU.
3 - to reduce the AOA by all means: prolong input of the sidestick, NoseDown, THR at idle, manual trim for ND.
They solved only the puzzle no. 1, partially.
https://www.youtube.com/watch?v=BR5kFOHVnUU

[Concours77]

So if they had the flight path vector alive, (the bird) does it point down to the sea? Which cue to follow, avoid?

With GPWS ordering "PULLUP", does the computer reject the actual attitude?

The GPWS commands the wrong move.

"DO NOT PULL UP! ASCEND" What's a computer to do?

GPWS: One trick pony. Not that it mattered.

Why do we suppose the Captain declared "PITCH ten Degrees..." 1.6 seconds before impact?

We have been told the attitude of the aircraft was accurate and available to the pilots.
From the FD?

If, after sixty seconds the speeds were accurate, (only thirty seconds prior to forever STALL), and the attitude was displayed, the FDs were active and correct, what is the predicament of the Pilot Flying?

250 knots, high (10-15 degrees NU) Pitch, heading 1 1/2 degrees per second turning right, And conceivably the FPV pointing to the floor, and high noise level.

What would you do? We determine that the pilots do not accept the STALLWARN as valid, so perhaps for the first time, can we forego the "...Get the GD Nose Down, and hold it down!..."

The 330 needed handling at loss of AP, fact. The Roll Axis was a surprise and a challenge to PF. fact.
The neutral point of the stick may have been displaced aft. fact. Max THS NU. fact. The roll remained split, throughout, fact.

With respect, what do you do?

[EMIT]

Vesbot,

Answer to your post 1520

You asked whether it is useful that a Flight Director comes back into view (is displayed again) after it has been removed from view because of unreliable data?

You dismissed my post 1522 as being not an appropriate answer to your 1520.

You have to realize that no amount of clever engineering can protect an aircraft against pilot actions like Mr. Bonin's.

If an F/D would remain removed from display, even though valid data would be available again, and would require the F/D switch to be moved from ON to OFF to ON in order to get the F/D back on display, then NO DOUBT in the future you will get a crash because another F/D slave will not be able to fly the aircraft BECAUSE HE HAS NO F/D TO FOLLOW (HE will be under the impression that when an F/D switch is ON, there SHOULD BE an F/D in view and he will never reach the point that he cycles the ON/OFF switch). After that future crash, PPRUNE will be full with posts why the hell those stupid aircraft builders don't let the F/D return to display (in accordance with the ON status of the switch) once the applicable data have become valid again.

So, if the AF447 Flight Director did come back ON in the V/S mode at the momentary vertical speed of 6.000 ft/min, that was in itself not particularly useful, but the proper way of using the system would have been, to announce (and so acknowledge) the flight mode annunciation of VERTICAL SPEED, to check the present rate as displayed in the V/S window on the Flight Control Unit, to conclude that a 6.000 ft/min climb was not what was desired, to adjust the value in the FCU V/S window to a more sensible value and to (only then) follow the flight director. In that way, the return of the F/D display could have been used in a useful way. Of course, pilots that would have been that clever, would never have pulled up the nose to 15 degrees above the horizon to begin with.

So, in reality, the answer to your question is not a simple Yes, useful or No, not useful. The usefulness has to be embedded in a proper way of using the system, and, sorry to say, the AF447 crew did not use their A-330 aircraft in a proper way, they f****d up big time.

For that crew, the most useful piece of equipment on the flight deck would have been a newspaper, in which they should have kept their noses deeply dug-in, until the 1 minute speed unreliability had passed. After that, all they had needed to do was to switch the autopilot back on.

[EMIT]

[QUOTE=Concours77;9836181]EMIT:
"The speeds were lost for sixty seconds. ATTITUDE? How would you know? From the report? PF PFD was not recorded, and he was flying. "We have NO INDICATIONS..."

I think PF was relying on his FD, which was int. I also believe, and from early on, believed his inputs were mimics of what he saw on FD."


If as you say the ATTITUDE was accurate, and should be employed in flight, you have isolated a disturbing circumstance where the Airplane was reinforcing there was no STALL, and arresting descent should be done by commanding NOSE UP....instead of a workable plan to regain aerodynamic flight....no?[/UNQUOTE]

Concourse77,

You are contradicting yourself - you assert that, according to an unprofessional, non-informational term about "screens" gone "crazy", that there must have been no attitude indication, but on the other hand, you assert that mr. Bonin must have been following Flight Director commands.
Let me tell you that the F/D is displayed right on the very screen that displays the attitude (the whole display is called the PFD, Pilots Flight Display). That PFD is such an important display, that should the Display Unit (that is, the display screen itself) fail, the PFD (the picture that is, the information) will automatically transfer to the other Display Unit, which normally displays the ND (Navigation Display).
And should, for whatever reason, all Display Units fail, go black, then there is ATTITUDE available on the completely independent, autonoumous standby attitude instrument (I use such a generic term because there are different forms of backup instrumentation available, however, the overriding quality of all those backup systems is that they will function on the most basic form of power supply and are completely independent of all the main systems).
As for your incredulous reaction to my observations about ATTITUDE being the most important control parameter for flying ... sigh ....
I see your join date on PPRUNE is annunciated as of late 2016 - please start a read-up of all previous posts in the existing 12 threads on the subject and also get better informed on how flying is actually done before you spout off with inconsistent theories.

[EMIT]

Concours77,

A picture is worth a thousand words, so I will try once:

Following pictures of a PFD of a representative airliner in climb at high level and in level flight.
Note that there is only a hear thicknness difference in pitch attitude between the two situations.
The third picture shows the same sort of display of an Airbus.

[wiedehopf]

@EMIT

there is a difference between a 6000ft/min climb and 500ft/min climb.

additionally you can have a higher angle of attack when you are not flying in the optimal range adding to the attitude.

[EMIT]

Wiedehopf,

Yes, I know there is a difference between a 500 ft/min climb and a 6.000 ft/min climb.

The most important difference is the fact that a 500 ft/min climb is just about the maximum that an airliner can MAINTAIN at that altitude and that a 6.000 ft/min climb CANNOT be MAINTAINED by an airliner at that altitude.
NOT BE MAINTAINED means that the airliner will loose speed when performing that kind of climb. It will trade speed for climb performance, or speed for altitude, however you will call it, but it can only be a temporary situation. Once the speed has dropped a considerable amount, you do not have enough speed left to sustain 1 g in level flight, you will have to unload, dive to pick up speed, etectera.

The pictures here are presented to show how close the climb ATTITUDE and the level flight ATTITUDE are and to make clear, in a visual way, for laymen, how absolutely idiotic a 15 degree pitch attitude is for an airliner at high level and how unequivocally clear the difference is on the attitude indicating instrument between circa 3 degrees and 15 degrees nose up.

[Vessbot]

Vesbot,

Answer to your post 1520

You asked whether it is useful that a Flight Director comes back into view (is displayed again) after it has been removed from view because of unreliable data?

You dismissed my post 1522 as being not an appropriate answer to your 1520.

You have to realize that no amount of clever engineering can protect an aircraft against pilot actions like Mr. Bonin's.

Nothing is an absolute solution, but that doesn't mean that we shouldn't enact mechanisms that have a partial chance of helping. And it certainly does not mean that we should leave in place mechanisms that have a high chance of leading the crew astray (threats). And this is one.

If an F/D would remain removed from display, even though valid data would be available again, and would require the F/D switch to be moved from ON to OFF to ON in order to get the F/D back on display, then NO DOUBT in the future you will get a crash because another F/D slave will not be able to fly the aircraft BECAUSE HE HAS NO F/D TO FOLLOW (HE will be under the impression that when an F/D switch is ON, there SHOULD BE an F/D in view and he will never reach the point that he cycles the ON/OFF switch).

A valid problem, but one easily solved by having that FD on/off control be a pushbutton instead of a switch. Then, there could be no mismatch between switch position and actual system state.

After that future crash, PPRuNe will be full with posts why the hell those stupid aircraft builders don't let the F/D return to display (in accordance with the ON status of the switch) once the applicable data have become valid again.

Well yes, lacking a FD to help a task saturated pilot with valid data would be a problem, agreed. But having a FD sneak an unnoticed mode change and lead a task saturated pilot into a zoom climb and stall, is a much bigger problem. In choosing which problem to design the system to account for (and the design solutions are contradictory), we're forced to choose between two evils. And I dare think that even without the hindsight of this accident, I'd say that the latter is the greater evil.

So, if the AF447 Flight Director did come back ON in the V/S mode at the momentary vertical speed of 6.000 ft/min, that was in itself not particularly useful, but the proper way of using the system would have been, to announce (and so acknowledge) the flight mode annunciation of VERTICAL SPEED, to check the present rate as displayed in the V/S window on the Flight Control Unit, to conclude that a 6.000 ft/min climb was not what was desired, to adjust the value in the FCU V/S window to a more sensible value and to (only then) follow the flight director. In that way, the return of the F/D display could have been used in a useful way. Of course, pilots that would have been that clever, would never have pulled up the nose to 15 degrees above the horizon to begin with.

You list a number of actions that a capable crew should have taken instead of mindlessly following the FD. And I agree with all of them - but this all presumes that they are capable, and that's where the mechanism breaks down: they weren't. Instead, they were overwhelmed and tunnel visioned past the point of being able to deal with this.

The point of a safety system is to catch or back up a crew at their last capable. If its design fails to do this, hammering harder on what the crew should have done misses the point. All those things may be true, but that's about the crew, not about the safety system in question. A different slice of the Swiss cheese being addressed.

The FD behaving the way it did is much more than "not useful" as you label it. It's specifically harmful. It needs to be redesigned, unless this need is outweighed by some opposite need. You touched upon such a possible opposing need, but I think it's not strong enough for the reasons I stated.

The FD design needs to be based on the assumption that it will be followed. And on that principle, it follows that a deadly command should not be displayed in the first place, rather than depend on the task saturated crew to do all this extra task sifting and ordering to fix it.

[_Phoenix]

You have to realize that no amount of clever engineering can protect an aircraft against pilot actions like Mr. Bonin's … and, sorry to say, the AF447 crew did not use their A-330 aircraft in a proper way, they f****d up big time.
For that crew, the most useful piece of equipment on the flight deck would have been a newspaper, in which they should have kept their noses deeply dug-in, until the 1 minute speed unreliability had passed. After that, all they had needed to do was to switch the autopilot back on.
EMIT, that’s the imagine portrayed for AF447 accident to mass media, unfortunately it is a convenient finding for some professionals (not only for biased).
AF447 pilots used A-330 aircraft in a proper way, 99.99% of the time, in normal law, which implies a synthetic flying. Flying the automation is one thing, but flying the alternate 2b (pitch normal+lateral in direct) is quite challenging at high altitude, in the night and icy thunderstorm. However, it is manageable for any trained pilot, including PF of AF447. He could fly it properly, if he would have the proper instrumentation and I’m not talking here about airspeed, FD, PFD, etc but about the No 1 instrument installed on the flight deck, that tells you if the wing is flying or not. That stall warning was triggered 20 seconds while the wing was still flying and vice versa was inhibited when they were falling like a stone. I agree with Vessbot, a task saturated pilot might follow the FD only (also a possible a convenient habit). A tunneled chasing of the cross bars might disregard the attitude, until is too late when the PFD is all blue. Yes, 15 degree pitch was idiotic, Bonin put them in the coffin corner with the feet on the wall, but I guess more troubling are the puzzles (listed in my previous post) to be solved in 2 minutes in order to recover an airliner from a stall, with all the sky underneath.

[Concours77]

"...Yes, 15 degree pitch was idiotic, Bonin put them in the coffin corner with the feet on the wall, but I guess more troubling are the puzzles (listed in my previous post) to be solved in 2 minutes in order to recover an airliner from a stall, with all the sky underneath..."

Then perhaps two "idiots" on the flight deck? Bonin, for consistent up ELEVATOR, and the A330 for full authority AUTOMATIC TRIM FULL NOSE UP?

1. Elevator alone cannot sustain 40 degrees AoA.

2. Elevator alone cannot prevent Nose drop at STALL.

2a STALL with elevator only is standard recovery.

3. Elevator alone cannot make the STALL so stubborn, and flyable in their state.

4. Recovery from inappropriate TRIM is not trained.

5. There are no "Human Data Recorders" available, how convenient, indeed.

"...That stall warning was triggered 20 seconds while the wing was still flying and vice versa was inhibited when they were falling like a stone..."

Perhaps picky, but STALL WARN sounds when wing is still flying. STALL WARN is ALERT of impending STALL. All pilots had ever heard was "Impending Stall", not "In Stall".....?

Without functional AoA indicator, and STALL AoA computed, no definitive conclusion of the wing's status can be had.

No one here posting was present at this accident. Please stop with the "idiot", idiotic", etc.

[Turbine D]

Nearly, if not all, your questions or poses have been covered in the previous AF447 11 threads, if only you would go back and get educated. What you are doing now is rehashing what has been reviewed extensively...

[Concours77]

Excuse me. You have something new? The only change possible in the outcome can come from a perspective.

It is likely futile, but there are those here who wish to look differently at the data, and re open what has become closed off. From the outset, there was one poster whose only contribution was limited to endless repetition of narrow minded blame about aft stick.

The conclusion can be amended. Some here are not convinced the cause of aviation is advanced by ignoring the aircraft's design flaws, and focus on the crew.

This one sided and trite approach is in the end costly, and ignorant.

There are no cold cases, only a wish to worship apathy.

[Winnerhofer]

Round 1: AF 0 Airbus 1
Family tries to go after Airbus but are rejected:
Rio-Paris: une famille déboutée de sa demande en référé contre Airbus - Le Parisien (http://www.leparisien.fr/toulouse-31000/rio-paris-une-famille-deboutee-de-sa-demande-en-refere-contre-airbus-31-10-2011-1695497.php)

[Centaurus]

It should not be forgotten that the original concept behind flight director use was that it was an aid to instrument flying and nothing else.

Unfortunately over the years, that concept has morphed into what many pilots understand the FD to be an absolutely vital ingredient for even basic instrument flying ability. That is despite evidence to show that loss of control has been the occasional result because of pilot blind adherence to following FD indications; even though it was obvious these indications led to over-controlling because pilots were "chasing" the needles.

If mode confusion exists - however temporary, pilots need to be trained to seamlessly revert from FD use to raw data flying,. Until that happens (very unlikely:confused:) loss of control will always be possible in todays high automated aircraft. Of course if the pilot lacks raw data instrument flying skills to be able to confidently switch off the FD, then that's another story..

[Concours77]

What would it take, once the "mush" was established, for the crew to think aft stick was crucial?

1. Any Nose Down would create: instantaneous acceleration and a large increase in vertical speed, down.
1a: shedding gobs of drag and introducing instability, esp. Roll.

2. Less noise (much less), but a worsening of roll reversals.... "Watch your lateral!!"

3. Reinvigoration of the STALLWARN.

What would Attitude look like, on the panel, if it was accurately reporting the decrease in Pitch?

If it was erroneous and showing too low to begin with, the only response possible would be aft stick, increasing Pitch, improving stability, with an increase in aerodynamic noise level.

More so than Stall discussion (there was none), the only remark was about Pitch.

Curious why Captain would report Pitch? At less than two seconds to impact?

[Machinbird]

Curious why Captain would report Pitch? At less than two seconds to impact?For a person who suspects he about to meet his maker, and doesn't know exactly how he got in that fix, that action is about the only choice left. It is too late to put the nose down and gain speed. From the Captain's viewpoint, if the plane was (possibly) actually flying, and the control system was (possibly) mis-behaving, then how else could you hope to level out/reduce the rate of sink.

Only problem was, as we know from our use of the retrospectoscope, they were deeply stalled and setting a climb attitude was like re-arranging the chairs on the deck of the Titantic.
Totally Useless!

[Concours77]

I agree. My sense of his (final) comment was that it was a "reset" of "SA". On the chance the VSI was duff, the stubborn attitude was bogus, etc.

[infrequentflyer789]

It should not be forgotten that the original concept behind flight director use was that it was an aid to instrument flying and nothing else.

Unfortunately over the years, that concept has morphed [...]

I am not sure it is the concept that has changed, but rather the users and their understanding of the concept. A workload reduction tool does something for you, but it is actually just a small change of interpretation/perspective between that and a tool that tells you what to do.

<begin rant (sort of)>

I think this is an inherent problem in human interface design - you are designing for an extremely adaptable animal, not just a moving target but an unpredictable one. It is also a generational issue, each generation trains the next - what is designed, successfully, as a workload reduction for the first generation (who lived without it) becomes a crutch for the next (who know how to live without it, but haven't had to) and for subsequent generations it becomes their master, because they have never even known of a life without it.

In aviation the generations are actually quite long - aircraft last for decades, aircraft _designs_ last for decades longer, but in other fields you can see this effect go through every stage in a handful of years. Particularly true in software where product UI can change radically between releases, in maybe less than a year, and where customers have users training users with the whole staff turning over every couple of years. In fact I didn't do UI when I did flying software, and it was only after seeing this sort of thing happen in other fields that I looked back at Children of the Magenta Line and really understood how widely it applies.

If there was some way to strip the aviation-specific language out of Children of the Magenta Line and generalise while keeping the impact of the talk, I would make that video mandatory viewing for any user or customer who asks for UI changes to make stuff "easier" or "reduce workload" (by which they almost always mean "so we can use fewer, cheaper, less trained people").

<End of rant, back to lurking>

[Capn Bloggs]

I think this is an inherent problem in human interface design - you are designing for an extremely adaptable animal, not just a moving target but an unpredictable one. It is also a generational issue, each generation trains the next - what is designed, successfully, as a workload reduction for the first generation (who lived without it) becomes a crutch for the next (who know how to live without it, but haven't had to) and for subsequent generations it becomes their master, because they have never even known of a life without it.
Hit the nail on the head!

[Concours77]

The danger is in the immediacy and the necessity to adapt to an environment that does not care about the interface.

Where the operating system meets intuition, that is the conflict. For too long the industry has travelled a road that frequently overlooks and diminishes the skills needed for intuitive operation in (thankfully rare) emergent conditions.

It is at its most apparent in the relinquishing of a traditional dependence on craft.

447 is instructive...

"Do nothing, read a newspaper..." OK. One cannot have it both ways: leave it alone, or utilize skills that have become vestigial and are dismissed as unnecessary.

One cannot claim a system (an aircraft) can be operated by minimally trained operators, then savage said operators when clearly old skills would have helped, and they were lacking.

Especially so when the system enters a mode that is not known, and recovery is not traditional....(or trained).

With the greatest respect.

[_Phoenix]

I think this is an inherent problem in human interface design
Problem solved. Bombardier CSeries designed the FBW as an energy-based control system that mimics the basics of how pilots learn to fly. When trimmed out, the aircraft will attempt to maintain that speed despite changes in power. If the power is lower than needed, the aircraft will descent, and vice versa, but the speed will attempt to remain constant, naturally. Bombardier modified the C* (C-star) FBW design control system to be speed-stable, meaning that the pilot is kept in the loop to maintain a speed set by using the trim switches at the top of the sidestick: “It's much more intuitive and flies much more like a conventional aircraft,” says Dewar. Compared to the Airbus FBW, where you trim to an attitude and it holds it, here you trim to an airspeed.”
Just watch the stick movements in video below:

CS300 Multicam Cockpit Landing (https://youtu.be/FHFsZc4okcY)

[Vessbot]

Bombardier modified the C* (C-star) FBW design control system to be speed-stable,

This is what's also in use by the 777 and 787. C*U

[vilas]

Compared to the Airbus FBW, where you trim to an attitude and it holds it. Really? No! you don't trim at all. The aircraft does and that too not the attitude but maintains the flight path. It's not the same as attitude. It doesn't hold the attitude.

[Concours77]

That got Bonin in trouble...The commanded flight path in manual was up, up, up.

And it took all the aircraft had in trim to hold. In ascent, and in descent.

[EMIT]

No, not the aircraft brought Bonin into trouble, Bonin brought the aircraft into trouble.

Everyone who pulls and holds full back stick in an airliner will bring that airliner down - works in any type, from any manufacturer.

Want to see the list again?
A B-727 with blocked pitot tubes in the nineteen-seventies.
A B-757 of Birgenair with blocked pitot tubes, where the autopilot maintained nose up and the autothrottle powered back (to keep the false speed indication below the limit)
MD-82 over Venezuela in 2005 and MD-83 over Mali in 2014.

Works whether the aircraft is equipped with Fly By Wire, or with "old fashioned cables", with interconnected yokes, or non-connected sidesticks, gues what, would even work in a single seater with only one set of flight controls, works with or without auto trim function; by the way, even a non-Airbus aircraft autotrims as long as the autopilot is in control, and, as in Mali, that could be up until the stall and wingdip.

[Concours77]

Poor grammar, Bonin indeed, not the A/C.

You miss one thing. The A330 is so adept and docile, it maintains the flight path through stall, without change in attitude, not consistent with its advertised fbw? So it morphs from flight path stable, to attitude stable in Stall, no? At least functionally, if not by design...

This is more the responsibility of the THS, to maintain good manners at +40 AoA?

"...by the way, even a non-Airbus aircraft autotrims as long as the autopilot is in control, and, as in Mali, that could be up until the stall and wing dip.."

Yes but AP was not flying. Manual flight for Bonin. Also in manual, the goal is to remain stable, to maneuver, not to cruise. Why Auto Trim for manual flight? The goal is maneuverability and stability, which demands equal authority in Pitch, not Nose Up or Down bias. Certainly not in low energy flight?

Airbus has added LEAP, an important safety improvement.... (Low Energy Alerting System)
Would an alert of low energy (STALL) separate from the STALLWARN have helped?

[vilas]

Airbus has added LEAP, an important safety improvement.... (Low Energy Alerting System)
Would an alert of low energy (STALL) separate from the STALLWARN have helped? It is not called LEAP. It's just called low energy warning. It is not available in Alternate law that's what AF447 was in. Nothing would have helped Bonin. He and his partner were simply not trained appropriately enough to deal with the situation and were overwhelmed. They put the aircraft in a region where no commercial aircraft is tested. It futile to discuss this incident.

[Concours77]

With great respect, commercial jet aircraft are indeed tested, laboriously and especially in this region.

Approach to Stall cannot, must not be left untested, nor can an aircraft be certified to carry passengers without demonstrating standard recovery responses.

It could be suggested that seven seconds past loss of AP began the long approach to the Stall, a Stall which is unlike other aircraft, and in no way "standard".

In the eight years and change since this horrific accident, literally all the discussion here is limited to hind sight, sensitive ego, and grandiosity.

The data is clear, but its impact on the crew virtually unknown.

Instead of a curiosity about how this aircraft entered and stubbornly sustained a docile and passive Stall, the "analysis" is quite limited in scope.

No discussion of the certification of AB FBW, and how they achieved a waiver of safety devices? Shaker? Pusher? No discussion of what the flight path result derived from related to handling in LOC (gentle? No natural Nose Down, etc.)

No review and analysis of Mr Winnerhofers video of the AB Stall training video?

Crickets.

It is troublesome, the willingness to post "Don't go there....it's futile..."

Futility was in evidence in their descent, with ten thousand hours, collectively, of Time in Type?

But you are correct, it is futile, and I've completed my responsibility....

Thank you for your patience, and kindness in responding to my concerns....

[Vessbot]

With great respect, commercial jet aircraft are indeed tested, laboriously and especially in this region.

Approach to Stall cannot, must not be left untested, nor can an aircraft be certified to carry passengers without demonstrating standard recovery responses.


Pretty sure that the "untested" region he's talking about is the ~40 deg AOA deep stall that the plane was in, not "approach to stall"



Futility was in evidence in their descent, with ten thousand hours, collectively, of Time in Type?


I would not expect them to be any more capable of recovering from the situation with that ten thousand hours of experience, than their first hour in the plane. After all, what would have happened in the intervening 9,999 hours to better prepare them? 9,999 standard takeoff and approach profiles? A few million stick back inputs where the airplane reliably went up as a consequence, each and every time? A couple of dozen recurrents in the sim where they applied power and held the nose in place in a "minimum altitude loss" type stall recovery? Yeah right, those hours made them worse, not better, prepared than a freshly minted private pilot.

It's not time in type that matters, but time in stall.

[Concours77]

"...It's not time in type that matters, but time in stall..."

Without question, and without disagreement. Likely no A330 crew will realize, or come to rely upon, the bizarre disguised Stall Entry of 447.

Gliders? Pitts? Extra? That time similarly makes for counterintuitive response to 330 Stall Entry....no change in Pitch, buffet easily confused with turbulence, and partial loss of roll control.... Full Nose Up trim without command (in manual), etc.

Perhaps better to enlist PPLs to fly this family? At least the Stall would be no less baffling to them. Perhaps retire them out of type after 2000 hours?

I thank you for your feedback, for I believe too much is left unsaid, the conclusion too pedestrian.

This was a challenge for any crew, that the holes lined up so well is their fate. Even a maladjusted seat and deployed armrest deserves some weight. All counter points neglected in the interest of peace...

[IcePack]

When I converted onto the A330, prior to this accident. Stalls done on the simulator were conventional. Holding s/stick back in alt law caused buffet and then a significant nose drop.
I am therefore not surprised that this unfortunate crew did not recognise the stall.

[vilas]

Approach to Stall cannot, must not be left untested Approach to stall? At FL370 if you yank the stick back the aircraft will be in region where it is not tested. That is why airbus forbids practicing deep stalls in Sim because there's no data available to make realistic simulation.

[wiedehopf]

if airbus likes their alpha prot so much maybe they should just enable it despite of lost pitots.
not sure how feasible that is though.

also having 2 very different roll behaviors obviously was a problem and major time consumer for the pilots. don't know either why roll input can't stay at roll rate ... the internal gyros where not affected afterall. either you unify the behavior of the aircraft or you need quite a bit more training for what are essentially two very different feeling planes.

[Concours77]

Approach to stall? At FL370 if you yank the stick back the aircraft will be in region where it is not tested. That is why airbus forbids practicing deep stalls in Sim because there's no data available to make realistic simulation.

From the report, Bonin's second brisk command in Pitch was Nose Down. Halfway through stick travel to neutral, the STALLWARN activated. He did not create the first SW by "yanking stick back". That is an airborne myth.

Please see Winnerhofer's post of the Stall training video issued by the company.

No Nose Drop, just loss of altitude from level. How long into Stall does "deep" Stall occur? From your comment, untrained deep Stall with gentle unremarkable entry is without precedent, by design.


Unfamiliar? An unobtrusive and untrained passive entry to Stall might confuse anyone? It is without contradiction that Stall was rejected by crew.

Once in very high AoA, any Nose Down produces remarkable acceleration and negative g. Sufficient to cause reversal by pilot of ND command. The record shows this? Add to this the return of STALLSTALL, and recovery is foreclosed, demonstrably....

[EMIT]

Stall warnings are not connected directly to stick movements, they are caused by airplane condition (angle of attack).
Initially the speed was normal. The yank back on the stick then pointed the aircraft 15 degrees nose high. That ATTITUDE at that ALTITUDE caused massive loss of speed, that loss of speed reduced lift, that loss of lift caused the aircraft to adopt a downwards flight path, the backstick of Bonin caused the ATTITUDE to remain very high, the attitude and flightpath together make for a high angle of attack, that causes stall warning. And of course the low "maximum angle of attack" at high Mach number makes for the possibility that the stall warning already went of during the pullup, while real airspeed was not extremely low yet.

If just around that time, an abrupt stick forward movement is started, but already stopped when reaching approximately neutral stick, then the aircraft does not really have time to react by decreasing pitch attitude.

Crucial mistake in your reasoning is, that the sounding of stall warning at the moment of forward stick movement, would convince Bonin of the need to pull back again. For every pilot, it should be bread and butter, that stall warning requires relaxing of back pressure, requires forward stick movement, not aft stick movement.
The only instance of stall (warning) requiring you to pull, would be in a negative stall (that is, with so much negative g applied, that the negative angle of attack is too great - however, that condition can only be concocted in an aerobtic aircraft. In a civvie airliner it could only occur when the horizontal tailplane has broken off and the wreck is then pitched forward by the negative pitch moment of the wing alone - and the wing would soon fail structurally - read accident report of Itavia DC-9 near Ustica in circa 1980 ).

Quote
Once in very high AoA, any Nose Down produces remarkable acceleration and negative g. Sufficient to cause reversal by pilot of ND command. The record shows this? Add to this the return of STALLSTALL, and recovery is foreclosed, demonstrably....Unquote


Application of forward stick would not magically produce negative g and massive acceleration. First, the whole aircraft would have to react (that takes time), the g load would decrease a little bit, slowly the angle of attack would decrease, thereby decreasing, slowly, the enormous amount of drag from the extreme angle of attack, and then initially slowly, the speed would increase. Then of course, matters would pick up pace and then again, carefully, aft stick would be applied to keep acceleration reasonable, acceleration (that is g!!!, not the increase of airspeed) reasonable, so as not to stall again, etcetera etcetera.

Perhaps you are under they impression that, while having the airplane act as a piano, falling through the air, that the crew was subjected to zero (or perhaps a little) negative g. Not so, it was falling steady state, more or less, and everything inside would be pulled into their seats by gravity with the normal load of approximately 1 g.

[Concours77]

"...For every pilot, it should be bread and butter, that stall warning requires relaxing of back pressure, requires forward stick movement, not aft stick movement..."

The first Stall Warn interrupted what was a brisk movement forward of the Stick. According to the graph, the Warning stopped, Bonin continued forward stick movement, and then gently added aft pressure to stick. Don't forget, he may have suspected coffin corner, and was trying to be judicious with Pitch. He also was trying to arrest the descent his ND started, with aft stick.

Pull back, Stall. Push forward, Overspeed.

"...Perhaps you are under they impression that, while having the airplane act as a piano, falling through the air, that the crew was subjected to zero (or perhaps a little) negative g. Not so, it was falling steady state, more or less, and everything inside would be pulled into their seats by gravity with the normal load of approximately 1 g..."

Now you are in Deep Stall. With your experience of Deep Stall, and a two hundred ton aircraft squatting on a cushion of thin air, you say forward stick produces gentle response?

I would say no. A brick, or any portion of it, losing its cushion, will accelerate quickly, and perhaps even start a tumble. If 447, balanced thusly, was stable or thereabouts, do you think pilot would risk stability to gain unwanted airspeed, exacerbating the already novel and robust instability in the Roll?

But this is Deep Stall. I refer to first Stall Warn, as shown in the report.

I have flown this maneuver, albeit in a small plane. Unless rudder and aileron are strictly controlled, the aircraft acts like a man trying to stand on a bowling ball. It leaks to the side, falls forward, or even seems to slip backward. It is exhilarating, and without prior experience, I suggest would be intimidating, to say the least.

[EMIT]

Give me the airliner that produces overspeed with the nose 15 degrees high above the horizon at FL380.

Must be a mighty powerful beast to play with.

[Concours77]

Addendum. Recovery from this maneuver, even in a light plane, takes a lot of altitude, and gentle pitch, to avoid a second experience. That I have not done.

[Concours77]

Give me the airliner that produces overspeed with the nose 15 degrees high above the horizon at FL380.

Must be a mighty powerful beast to play with.

Exactly, but who knew?

[Turbine D]

But this is Deep Stall. I refer to first Stall Warn, as shown in the report.

AF447 did not enter a deep stall at 38,000 ft. It was a conventional stall. Deep stalls occur mainly on aircraft with rear mounted engines and a T-tail design. Aircraft that employ the canard design feature are prone to deep stalls if preventive measures are not included in the design. A-330s don't have a T-tail, rear mounted engines or canards and don't deep stall.

[Vessbot]

Yes it did, AOA for most of the ride down was about 40 degrees. Typical stall AOA is about 15 to 20.

[Concours77]

Turbine D,

Point taken, but there is no other way to describe the Stall. It didn't help having full Nose Up Trim, and under slung engines at full chat (which induces nose up). Once the wing unloaded, and THS remained all NU, the elevators became trim tabs. Also, this aircraft is longitudinally stable, it resists emphatic changes in Pitch something the "trim tabs" though recorded, had little effect...upon.

Once the aircraft "settled in", it may actually have seemed docile. But the recovery shouldn't have been necessary anyway. As Wiedehopf points out, in Alternate Law, the 330 becomes a different "beast".

[Turbine D]

Vessbot,
Perhaps this will help you on stall understanding:

http://www.sftentx.com/files/75234188.pdf

[CONF iture]

Yes it did, AOA for most of the ride down was about 40 degrees. Typical stall AOA is about 15 to 20.
AF447 did not enter a deep stall, but a fully-developed stall.
Nothing indicates it was impossible to get out of that stall situation with proper flight control inputs.
The main culprit and obstacle was that unbelievable fully nose up auto trimmed THS ...

[Concours77]

Deep Stall. Nomenclature. Critical to a technical approach, without doubt.

1. How did it get there?
2. What made it (functionally) not recoverable?
3. What issues in the AC design made it (inadvertently) fatal?

Three poorly designed, inadequate pitot systems, due to be replaced by a line that did not take seriously the vulnerability of the aircraft in conditions that were frankly typical of the airspace. Threat of a pilot strike finally got them to take action....

Full thrust, bleeding energy, loss of lift at the outer wing, Chronic NU command. Direct Law in Roll, the betrayal of the STALLWARN system, turbulence, cockpit disarray (visitor). Delayed recognition of the loss of speeds display and Normal Law by pilot crew. (Fifteen seconds). One can make the argument that the loss of speeds and Normal Law, caused by Thales Pitots, was the direct and sole cause of the ultimate impact with the ocean.... "Shoulda, Woulda, Coulda...."

Then the piece de resistance, a full up HS.
Stall entry unnoticed, and a mental lock on issues other than those that would cause a recovery.

The word "cascade" comes to mind. This is not a simplistic and isolated wreck.

[Ian W]

It looks very much like flying 'on the wrong side of the drag curve' this is a stable state and if your aircraft has sufficient power then the lift is supplemented by the power from the engines as they have a significant upward vector due to the nose high angle and the aircraft will happily fly straight and level at below its normal stall speed 'sitting' on the power. Can be fun if you can see what you are doing.
If the aircraft is at height and power to weight ratio is not good or power is reduced the aircraft will drop - quite fast - as AF447 did. The nose high attitude must be maintained and for that the tail plane had motored into full nose up 'trim' - and every throttle increase with underslung engines also assisted the nose up attitude. This is not a classic stall.

The aircraft is now in a stable nose high state dropping faster than its forward speed. Unwittingly, PNF by insisting that PF kept the wings level assisted in the maintenance of the stable state. Had PF lost the roll control the aircraft would have rolled out of its stable state - perhaps before the tail had motored to full NU. That would have provided a more 'conventional' LOC that they may have recovered from. As it was they sat on the wrong side of the drag curve all the way to the surface.

[infrequentflyer789]

Bombardier modified the C* (C-star) FBW design control system to be speed-stable,This is what's also in use by the 777 and 787. C*U

Before even hinting that C*U might be a solution to AF447, one should consider what it becomes when U (ie. speed) is unknown...

787 is, I believe, slightly different in that if speed is unavailable it calculates a synthetic airspeed from AOA and other data both for display and use in the control laws. This might have been developed with an eye on the vulnerability of C*U to loss of U.

C*U hasn't been without its problems though:
https://www.flightglobal.com/news/articles/boeing-faa-warn-787-pilots-of-bad-airspeed-data-423735/
https://www.atsb.gov.au/media/5773029/ao-2015-149-final.pdf

Pitot icing, plane's computers can't cope, yet again (even with the synthetic airspeed).

to quote the second link:
In response to a previous, similar event on another B787-8, the FAA published an airworthiness directive warning flight crew not to make large abrupt magnitude flight control inputs in response to
unrealistic drops in airspeed.

Boeing also revised the flight control software to limit the rate of elevator feel reduction with drops in airspeed. This will specifically allow the column to stay at a higher feel force to mitigate large and abrupt unintentional pitch inputs.

So, C*U is not quite the fix-all some seem to think it is.

Another salient quote from that report:
In this case, the crew showed a high level of professionalism in response to a weather related event. The crew demonstrated high levels of communication and coordination, promptly applied checklists and procedures.

And therein, I submit, lies the crucial difference between making it home and ending up at the bottom of the ocean.

[Vessbot]

You guys seem really wedded to the definition of "deep stall" being limited to the particular blanked stabilizer phenomenon in T-tails. Or otherwise diminished pitch authority. Fine, I'll live with it. Nevertheless, this airplane was very deeply stalled.

And Turbine D, there's no need to act like an :mad: about it.


I have flown this maneuver, albeit in a small plane. Unless rudder and aileron are strictly controlled, the aircraft acts like a man trying to stand on a bowling ball. It leaks to the side, falls forward, or even seems to slip backward. It is exhilarating,

[...]

Also, this aircraft is longitudinally stable, it resists emphatic changes in Pitch something the "trim tabs" though recorded, had little effect...upon.

Once the aircraft "settled in", it may actually have seemed docile.

This is an interesting point. Normally, if you asked anybody, they would say that a transport airplane should have docile stall characteristics, so as to limit workload (and potential for further upset) in a recovery. Now, it seems to me at least plausible that this docile behavior contributed to a lack of stall identification by the crew. Talk about a double edged sword!


Perhaps better to enlist PPLs to fly this family? At least the Stall would be no less baffling to them. Perhaps retire them out of type after 2000 hours?


Well, everything I wrote about the airline flying experience wrt. the maintenance of basic flying skills outside the normal airline profiles, applies equally to non-Airbus types. So, we'd be in a real pickle if we apply that solution industry-wide! (I know you're being tongue in cheek, of course.)

[Concours77]

"...Because the Aircraft remains safe even when the pilot pulls on the stick to the stop thanks to the high angle of attack protection, Airbus position is that no additional alerts about low speed/energy situations is needed at high altitude because large altitude loss due to stall cannot occur on Airbus Fly-By-Wire aircraft.

Moreover, no additional stall warning or stick shaker is needed with this kind of protection. Stall warning is only re-introduced on airbus aircraft when the angle of attack protection is lost (loss of normal laws)...."

ASHWG LAA Report_15 March 2010 Final Version_Appendix 1

Fair enough. What of performance after reversion to alternate Law? Stall Warn should compel action. If ignored, or dismissed, there is no other resolution for Airbus pilot. Shaker is unmistakable, irrevocable and emphatic compulsion to act.

So. Why the waiver from FAA? I would understand the waiver if clearly limited to Normal Law, the alpha Prot is its own Stall Warn, and cannot be overridden.

Alternate Law is a "different" airplane, should it not be required to meet minimum standard of other aircraft?

Roll in Direct? Perhaps a clever way to introduce instability in Roll, and a clever way to provide Nose Down, independent of crew? Unstable roll axis is perhaps the only Stall cue they would receive? Did Bonin outfox the airplane, and himself, by learning to manage the new roll? Or was the aircraft supposed to roll until the nose dropped, by design? Stick and rudder by program?

What this crew needed was instability in the descent, not docility. They were focused on stability as always, like all good Airbus drivers?

[Houba]

I ve tested several times a very good malfunction in the box: Volcanic ash. It is a nasty one because both engines are not usable and all your pitots are blocked. 777 is a democracy, if 2 out of the 3 pitots are blocked the ADM that are in majority reporting the same speeds are "winners into the election" for best data. In other works you will be prompted with erroneous speed for a while, till you hit 80 kts IAS and then the last ADM will be "elected". Back to that malfunction, your best friend would be the weather briefing with winds (predicted) and GPS ground speed since you cannot apply pitch, power, performance trick.

[Concours77]

IRU? Why waste inertial data. Ice and ash immune...

[Winnerhofer]

Preflight WX: charts were outdated and crew simply could not read them properly as on page 5.
AF are in the stone age regarding WX as they did not do provide any satellite indications!
AF 447 LE PLAN DE VOL AF447-Plan de vol. - ppt télécharger (http://slideplayer.fr/slide/1163083/)

[gums]

Great point(s) Vessbot

You guys seem really wedded to the definition of "deep stall" being limited to the particular blanked stabilizer phenomenon in T-tails. Or otherwise diminished pitch authority. Fine, I'll live with it. Nevertheless, this airplane was very deeply stalled.

And Turbine D, there's no need to act like an http://cdn.pprune.org/images/smilies/censored.gif about it.


Years ago, like thread 5 or 7 or 9, I tried to make the point that the 'bus must have nice stability and low buffet when at a high AoA. So defeating any of the remaining "protections" ( God, how I hate what that term implies) by holding a nose up command as the speed rapidly decreases makes for a "smooth" stall entry and except for the degraded roll control laws the sucker just sits there happy and descending at 10,000 feet per minute.

I can understand that the crew could not readily accept that they were deeply stalled. Ask a "delta" pilot like me in my early years, of any type - F-102, Mirage, F-106, Vulcan, Concorde, and so on. Very smooth transiton from lift to no lift and plenty drag and vertical velocity you do not want. My recollections of the Deuce was it had a "buzz", but no wing rock or buffet that I had in the other 3 or 4 planes I flew. But the bottom fell out on short final if you pulled back a lot with low power. So I cut some slack for the crew recognizing their stall entry, but only a little. Lack of understanding the confusing degraded control laws and failure to just hold whatever control inputs were there when the aero sensors went tits up and the AP kicked out did not help at all. Lastly, as CONF pointed out, the THS trimming while in a backup mode was the icing on the cake.

I am not gonna demand all the newer folks here go back thru the thousands of posts where we dissected this terrible crash, but maybe using the "search" features one could see "deep stall", "longitudinal stability", control law regression, and many more aspects of the crash.

[Concours77]

Moreover, no additional stall warning or stick shaker is needed with this kind of protection. Stall warning is only re-introduced on airbus aircraft when the angle of attack protection is lost (loss of normal laws)...."

ASHWG LAA Report_15 March 2010 Final Version_Appendix 1

Fair enough. What of performance after reversion to alternate Law? Stall Warn should compel action. If ignored, or dismissed, there is no other resolution for Airbus pilot. Shaker is unmistakable, irrevocable and emphatic compulsion to act.

So. Why the waiver from FAA? I would understand the waiver if clearly limited to Normal Law, the alpha Prot is its own Stall Warn, and cannot be overridden.

Alternate Law is a "different" airplane, should it not be required to meet minimum standard of other aircraft?

Does there not seem to be a large omission here, gums?

Each time the crew experienced the STALLWARN, it should have been preceded by a stick shaker.

If, in AltLaw, the "cannot Stall" morphs into an aircraft that can not only Stall, but does so so subtly that a separate device must be required ?

It occurs to me that if the shaker was shaking without stop all the way down they may have tumbled to the state of the aircraft?

[Owain Glyndwr]

There appears to be some misunderstanding of the character of high altitude/high Mach No stalls on current transport aircraft. On designs using supercritical wing sections on which upper surface flow breakdown starts at or near the TE and for which the design span loading leads to the critical maximum local lift coefficients being located about two thirds semispan the loss of lift is only slightly aft of the CG, so any pitch up is indeed mild. This is true no matter which side of the Atlantic the design comes from. The limiting factor in cruise conditions is buffet and in fact “stall” is usually defined by buffet reaching +/- 1g vertical acceleration at the pilot’s seat. The A330 high altitude/cruise Mach No stall data published in the second “Expert’s Report” (in French only unfortunately) shows this occurred at about 9 deg AOA on a simulated AF447 test, accompanied by +/- 0.5g lateral acceleration. I’m no pilot, but surely this sort of environment is not “benign”?. The authorities obviously think that this level of buffet plus a verbal stall warning announcement constitutes compliance with FAR 25.201 d (2).
The recent publication of a joint Boeing/Airbus paper “Stalling Transport Aircraft” (Society of Flight Test Engineers) makes interesting reading in this respect. For those who don’t want to bother, here are some relevant extracts (my emphasis)
<At high altitude/high Mach number, the Vs1g cannot be determined due to early triggering of buffeting. This buffeting is caused by local shock waves which excite the structural modes of the aircraft. Theoretically a ClMAX may exist at high Mach number but the associated level of buffeting prevents efforts to identify it during flight tests for aircraft structural integrity and safety reasons.
Nevertheless, according to the regulation a minimum of 1.3g maneuverability up to “buffet onset” must be demonstrated for each flyable Mach number. Therefore the ClMAX for a given Mach number will generally be defined by the level of buffeting corresponding to ±0.1g vertical acceleration level measured at the pilot’s seat (so called “buffet onset”) and is named ClBUFFET

Pitch up
“Pitch-up” can be observed during stall mainly on aircraft fitted with swept wings. It is due to the sudden loss of lift on the outer part of the wings, which creates a nose-up moment (see Figure 7). This phenomenon can also occur at high altitude/high Mach well before ClBUFFET is reached and is again due to shock waves destroying the lift on the outer part of the wings.

Expected 1g stall characteristics of large aircraft
Typical stall characteristics of transport aircraft in 1g non-accelerated flight (ref FAR Part 23.201) begin with the onset of initial buffet. This is best described as light airframe buffet which begins a few knots prior to stick shaker. As the aircraft approaches Clmax the level of buffet generally increases and can become severe to deterrent in nature. It is not uncommon to see buffet with a repetitive load factor of ± 1 G in the vertical direction and ± .5 G in the lateral direction (see Figure 20). It feels similar to driving an automobile across railroad ties. Buffet on large airplanes tends to be much greater than experienced in smaller aircraft. This is due to wing airflow separation and turbulent airflow vortices which produce a strong excitation forcing function on the wing. This excites the fundamental frequency of the fuselage leading to large vertical and horizontal deflections. It can be very evident on the flight deck, where anything not securely tied down, such as an errant water bottle, can get hurtled into the air.
Stall identification is deterrent buffet for most recent models in the clean wing configuration
Certification Stall Requirements for FBW Aircraft
Stalls for certification are performed initially at forward CG to determine the stall speeds that will be used for speed computations. For FBW aircraft, stalls must be performed in Normal Law to demonstrate the ability to control the aircraft throughout the stall and recovery, should an inadvertent stall occur despite the protections (for example, in the case of severe windshear). Because the angle of attack limits in Normal Law prevent the aircraft from stalling, a specific version of the Normal Law is created which shifts the limiting AOA to a higher value (usually by 10 degrees). Additional stalls are then performed in Degraded Control Laws, in all configurations, and at aft CG. For stalls in Augmented Control Laws, it is essential to place the stick forward of neutral during recovery, since the C* law is g-demand law, and neutral stick is a 1.0g command. If the stick is not placed forward of neutral, more nose up elevator than desired will be applied at the stall break.
Stalls at high altitude are not required in the classic sense. Instead, a series of wind-up turns are performed at constant Mach number to determine buffet boundaries. This determines how much g the airplane can sustain before the airplane begins to buffet, which is useful to the operational pilot when flying at maximum altitude for a given weight. If the airplane is flown too slowly, there will be an increase in buffet to the point that altitude will have to be sacrificed to regain speed. The same holds true if the airplane enters turbulence which applies g loads higher than the buffet boundary for a given Mach/altitude/weight combination
Stalls at High Mach Number
Stalls at Mach numbers normally associated with cruise flight (0.78-0.89 Mach) are not possible in level flight because Mach number decreases as the airplane decelerates. This increases Clmax and effectively increases the margin to the stall. It is difficult to tell when the test point will end, because the end point is shifting. Angle of attack limits for safety are equally difficult to predict. As the airplane decelerates, the level of buffet increases significantly and rapidly becomes deterrent buffet. The g-break may be difficult to recognize, either from the g trace, or the Cl trace, therefore a rapid change in vertical velocity may be the first good cue of the stall. Pitch-up may be present during deceleration, complicating the pilot’s ability to smoothly control pitch with increasing levels of buffet.>

[Uplinker]

I strongly believe that there should be a stick shaker on every aircraft.

No matter how clever a FBW system might be, the haptic (touch and feel) feedback of a shaking stick/yoke and the unmistakable message it gives you is a fundamental aspect of flying - one that we all learned on day three while learning to fly our Cessna 152's.

Several dozen pages back in this thread I gave an account of when I was given the AF447 scenario in the SIM, without knowing it was coming. Afterwards I said to the trainer "but the 'stall stall' never sounded". The trainer said, "yes it did, it was going all the time".

I simply never heard it - my brain ignored it completely.

Secondly, I think that stall practice should be mandated by the XAA's for every SIM we do. In the SIM we always practice an engine failure on take-off, a single engine (or OEI) approach, a single engine go-around and a single engine landing.

I think a couple of stalls should be added to this list of mandatory items because in modern FBW aircraft, we never experience even an incipient stall, so we forget how to recognise the signs and we lose the correct reflex action to a stall that we should all have.

[Goldenrivett]

Hi Uplinker.

I agree the stall warning should be "shaker". When the flight deck of AF447 was swamped with visible warnings and a continuous audible "C Chord" altitude deviation warning, I guess their brains filtered out the "C Chord" whist they turned their attention to the other visible messages. When the "Stall Stall" warning replaced the "C Chord" (higher priority) neither crew member commented (they probably didn't notice - like a ticking grandfather clock).

If you examine the flight deck transcript in the 2nd interim report, the "C Chord" was never canceled. It was only interrupted by "Stall Stall" and GPWS "Pull UP".

This U tube video shows how the brain can filter out repetitive audio warnings.
https://www.youtube.com/watch?v=YffmapFxt0M

[gums]

Not sure when Okie flew the Viper, but in the very beginning we were surprised that we could get the rascal into a a deep stall. Regardless of how you got there, the jet would maintain close to wings-level with no serious yaw and nose high unless inverted. Vertical velocity was about like AF447. All this was with fully finctional aero data from the pitot-static systems and the AoA sensors and the rate/gee sensots in the computer boxes.

Unlike the 'bus, our system cut out the stick and rudder once AoA was above 30 degrees. GASP! What could we do? "You can't stall this jet", but we found a way. Sound familiar? We had the Aces II seat. AF447 crew plus many pax did not, but three professionals did not realize they were stalled for almost 4 minutes until St Peter told them.

GD put in the manual pitch override feature and we could "rock" the sucker outta the deep stall, as above 35 or 40 degrees AoA the tail was capable of inducing a nose up pitch movement, but not nose down. So unlike the 'bus system, we could further increase our AoA and the nose would fall thru after a push/pull sequence while coming down at 10,000 feet per minute. Fun huh?

I never got into a deep stall, but came close and what happened was a "airshow" tail slide. Vertical zoom and ran outta speed too quickly or the system to save me. Sucker came back down and flipped over due to gravity and some tail surface aero. Once nose pointed down and AoA under 30 deg, the stick worked and simply reset the warning lights to continue the engagement.

I really think I personally could get the 'bus into the deeply stalled condition using the same profile we had in the Viper. You had to get the nose very high before running outta power. Once the speed decreased significantly faster than your power could hold it and allow the AoA laws to work, so you could get beyond the parameters that all the engineers never thought of or programmed into the computers.

I like the stick buzzer idea, but in the 'bus the feature does not seem to work if IAS is too low, or lost like AF447. And we must remember that the stall is AoA related and not gee or attitude or speed. Sheesh, day one lesson in flight school or with a good pilot as I had first time I ever flew on a joy ride.

Thanks for the rehash of aero stuff and such, OG.

[Concours77]

I wrestled for some time trying to understand Bonin's chronic "Aft Stick".
First it was tempting to blame his poor seat position, the inappropriate placement of armrest for the controlling hand, (right arm), or turbulence.

Now, I believe Bonin simply did not allow for the aircraft's AUTOMATIC Nose Up Trim from the THS. Neither did he allow for the Nose UP moment of the fuselage due to full thrust from the engines. At Stall, having lost outboard lift from the wings, the Nose went further up, and he was chasing a stick neutral point that was decidedly forward of neutral as he knew (expected) it to be. Was it the result of startling aerodynamics, design, and lack of Stall training? I believe he descended all the way without adjusting for these factors. This has been in the back of my mind since the wreck was discovered and the final report.

Whatever prompted Bonin's "But I have been holding aft stick for some time..."? I believe whatever possible solution Robert had in mind, Bonin had already thought to try. Why did Robert (emphatically) demand "Climb, Climb, Climb..." After Bonin responds, Commandant demands "NO NO NO, don't climb". Robert may have meant "ascend". Bonin may have heard: "pull, pull......" This exchange is fraught with mystery, and sadness; confusion is so apparent.....

So, the aircraft has just taught Bonin not to recognize the aero at Stall due to its inherent stability, and to misjudge the quadrants of the stick, ("the aircraft cannot Stall"), and the piece de resistance? StallStallStall when forward stick is applied and indicated airspeed exceeds sixty knots... Counterintuitive, poor design, and fatal.

Plenty of room under these circumstances to allow for some retrospective slack in the armchair judgment that is traditional in these threads. At least insofar as the stick is concerned. This is not sympathy nor defense, it is the truth as I see it.

There's more.....

Poor weather brief, "triple redundant ADIRUs" that simultaneously fail due to known but unmitigated design flaws and failure to replace the Pitot components pursuant to regulatory and mandatory orders.

At gums post #1397.... (not that long ago)

"- The jet has really great aero to get into a stall without obvious shaking, buffet, wing rock and so forth."

From my post #1403...

"gums,

"- The jet has really great aero to get into a stall without obvious shaking, buffet, wing rock and so forth."

I think that is intended as a compliment.... I think it is actually an indictment.

[Owain Glyndwr]

@OK465

I agree with you! At our age carping can be a waste of valuable time :-)
I was surprised by your remark on the effect of airspeed decay rate on deterrent buffet level. I think I have read most of the published official and semiofficial papers on AF447 but I don't recall ever seeing that comment. Neither can I think of any aerodynamic reason why it should be so.Anyway, driven by a combination of curiosity, a sleepless night and boredom I did go back to the final BEA AF447 report.
I couldn't find any reference to your remarks in that document, but I did find that they say stall warning was triggered at 02:10:51 and from Fig 67 the computed airspeed at that point was about 216 kts (on a lousy scale!). BEA then concluded that the aircraft reached deterrent buffet at 02:10:57, at which time the computed speed was 211 kts. Given the quality of the graphic that's as near as maybe 1 kt/sec. The deceleration increased after that of course but that is to be expected when the aircraft enters a stall.
At the moment I don't see any reason to change what I wrote, but if you do locate a reference I would be very interested.

[gums]

The buffet in the 'bus most likely manifests itself if you are approaching the "critical" AoA fairly gradually. My VooDoo told me real early, and a degree or so before the "pitch up". My straight wing planes only told me a degree of Aoa before the stall. My swept wing jets other than the F-102 did not have a distinct "break" in the buffet/burble. The Viper had no distinct buffet and simply went onto a deep stall or not, depending upon entry conditions.

All the references to stall and such that use knots or mph or furlongs per fortnight are based upon one gee flight and st-and-level. But Orville taught me that the AoA was what we had to pay attention to. I can take anoyone here up in a Cub or new trainer and show/teach the "feel". If the nugget can't feel the burble, then I recommend going to transports.

[EMIT]

Unfortunately Gums, civvie airliners are a sort of "transports" - I guess you catch my drift ...

[Ian W]

Going back to my time in single jets, when I pulled up into a stall turn at well above stalling speed at high g and then relaxed the pull on the stick when nearly vertical. With insufficient power to keep going up the aircraft would start dropping backwards - the aircraft definitely stalled -but at no time was there any pre-stall buffet as at no time was lift being demanded at high AOA.

There can only be buffet from an aerofoil attempting to produce lift at an AOA that results in the airstream breaking away into a turbulent flow. It is the pre-stall turbulent flow that creates the buffet. Pull above your aircraft ceiling in a zoom climb and relax the pressure at just the right time and you can go past the stage where there could be buffet as you are not demanding lift but the aircraft is in a more upward ballistic trajectory slowing all the time. Maintain attitude by putting full power on the underslung engines that cannot provide sufficient lift but will keep the nose well above normal AOA with insufficient power to drive out of the stall. The aircraft is now on the wrong side of the drag curve both wings stalled and the aircraft starts to drop in a nose high attitude. I doubt that at any time that there was any noticeable pre-stall buffet.

A late addition - this way of entering a stalled condition using engines to 'sit on the power' will also not result in a nose drop especially with underslung engines at high thrust and a pilot intent on keeping the wings level. Reducing the thrust or allowing a wing to drop to fall out of the stable stall would have resulted in a nose drop and recovery.

[Turbine D]

I suppose if one performs enough tasks wrong or not at all and doesn't respond soon enough to warnings, even an AOA display can't save the day:

http://www.airforcemag.com/AircraftAccidentReports/Documents/2013/122712_F-16C_Fresno_full.pdf

[gonebutnotforgotten]

..... or as one wise ex-boss, and very good engineer, once told me, 'this [thing] is fool proof, but it's not bloody fool proof'.

[Winnerhofer]

Endless...but what do you expect when France only spends 1% of its GDP on justice!
Long awaited 3rd technical report by independent panel delayed until 15 October much to the anger of anti-Airbus class action suit.
This time AF is going to be strung up and the writing is on the wall!
https://www.francebleu.fr/infos/faits-divers-justice/crash-du-vol-rio-paris-la-justice-accorde-un-nouveau-delai-pour-le-rapport-d-expertise-colere-des-familles-de-victimes-1504620249

[Winnerhofer]

https://www.theregister.co.uk/2017/03/03/raf_voyager_pilot_andrew_townshend_dismissed_plummet/

[Winnerhofer]

https://www.youtube.com/watch?v=2cSh_Wo_mcY&feature=youtu.be

[Winnerhofer]

Are the claims of ?psycho automation? in regard to Qantas flight QF72 justified? | RealKM (http://realkm.com/2017/05/19/are-the-claims-of-psycho-automation-in-regard-to-qantas-flight-qf72-justified/)

[Concours77]

Absent the "psycho" pejorative, 447 did indeed experience a "single event effect". Which one? A rather pedestrian failure of a system touted to be "triple redundant", it was no such thing. Redundancy implies separate (back up) system, or at least, alternate source, not "common failure of three identical sensors....collecting periodically and equally discordant data....resulting in erroneous and NCD output."

Producing a disruption in auto flight, a decay in flight law, and uninterrupted full travel of auto trim to full up pitch.

[fizz57]

Perhaps you can clarify how "A rather pedestrian failure ..." produced "uninterrupted full travel of auto trim to full up pitch." ?

On second thoughts, don't bother.

[Winnerhofer]

https://criticaluncertainties.com/2015/03/01/malcoms-horizon-and-unusual-attitude-recovery/

[Winnerhofer]

Latest official report blames pilots 100%
Crash du Rio-Paris : une nouvelle contre-expertise met en cause les pilotes - Le Parisien (http://www.leparisien.fr/faits-divers/crash-du-rio-paris-une-nouvelle-contre-expertise-met-en-cause-les-pilotes-11-01-2018-7495923.php)
https://www.lci.fr/justice/crash-du-vol-af447-rio-paris-une-nouvelle-expertise-met-en-cause-les-pilots-les-familles-a-la-limite-de-l-ecoeurement-2075728.html

[Winnerhofer]

https://criticaluncertainties.com/2017/12/15/unreliable-airspeed-again/

[Lonewolf_50]

@Winnerhofer
Posting a link without comment is hardly a worthwhile approach.
I actually found the link you posted to be a thoughtful piece, but I'd be interested to see what about it you consider to be of worth to this particular accident as concerns a professional pilot.

[Ian W]

It may be something worth quoting when in front of a beancounter's leather top desk, being berated for FOQA showing a period of manual flying in cruise and the potential extra 5kg fuel burn... deskilling and the potential issues with the extra stress of an incident while less confident is a threat that everyone should be aware of.

[Winnerhofer]

wfpalmer 15/01/2018 at 8:47 am
It’s not like Airbus has done nothing. Have they gone back to redesign and recertify the A320/330 flight control and airspeed indication systems? Well, no. But, they have designed and implemented a much more robust airspeed indication scheme for the A350 where data on the PFD automatically switches between sources and if all the pitot tubes are blocked will then switch to a system that displays airspeed based on data provided by the FADEC (engine cowl pressure sensors)and AOA data.

Additionally, the autopilot doesn’t just click off when the going gets tough but enters an extended protection envelope where it will attempt a recovery back to the normal flight envelope. This extended envelope includes extremes in speed, AOA, pitch (50° up!) and bank (120°). Indeed, the A350;s autopilot can remain engaged (or be reengaged) even in cases of dual engine failure, complete hydraulic failure and emergency electrical configuration!

>> For example in the Airbus design although AoA and Mach number are calculated by the ADR and transmitted to the PRIM fourteen times a second they are not directly available to aircrew.<>For example in the Airbus design the current procedure is to reach up above the Captain’s side of the overhead instrument panel, and deselect two ADRs…which ones and the criterion to choose which ones are not however detailed by the manufacturer.<<

This procedure applies when the AOA probe is stuck/frozen and the airplane inappropriately enters an alpha protection mode (i.e., it wants to pitch down to correct a high AOA). This is not an unusual airspeed recovery procedure. It doesn't matter which two ADRs are selected off, as the objective is to force the airplane out of Normal law where that protection operates. Perhaps the crew will have had some indication from prior failures which of the ADRs is most likely to blame, but for the immediate action it doesn't make any difference. The objective is to regain positive control of the airplane.

[Lonewolf_50]

@Winnerhoffer

Is any of that your own work, or did you just cut and paste again? Please use quote blocks using the square brackets {quote} what you are quoting {/unquote} around that which is what someone else posted, or use italics.

What you present to us is barely coherent.

[Concours77]

Winnerhofer,

“Additionally, the autopilot doesn’t just click off when the going gets tough but enters an extended protection envelope where it will attempt a recovery back to the normal flight envelope. This extended envelope includes extremes in speed, AOA, pitch (50° up!) and bank (120°). Indeed, the A350;s autopilot can remain engaged (or be reengaged) even in cases of dual engine failure, complete hydraulic failure and emergency electrical configuration!”

As an answer to 447? Save TRIM, wasn’t the 330 eminently controllable with loss of (displayed) speeds? Wasn’t the loss of data the exact reason the Autopilot quit?

So, with bad airdata, autoflight is a good idea?

[Winnerhofer]

https://www.ladepeche.fr/article/2018/01/20/2725565-verite-eclate-crash-attends-desormais-proces.html

For the father of a victim, "the truth broke on the crash, I'm waiting for the trial"
Flight AF 447 Rio-Paris disappeared - Michel Mommayou, the father of one of the victims of the flight Rio - Paris

Eight years after the crash of the Rio - Paris flight, the latest judicial expertise confirms the serious mistakes of the Air France pilots. A decision that, unlike the president of the asso families of victims, relieves, the father of Virginie Mommayou. The 35-year-old Tarn-et-Garonnaise had died with the other 227 passengers.

In front of Michel Mommayou's office, Virginie's radiant smile contrasts with the tragedy that the sexagenarian has been facing for almost nine years. On June 1, 2009, the life of his daughter who returns with a friend of a trip to Brazil, stops abruptly. She is one of the 228 victims of flight AF 447, one of the largest air crashes of the French company. Relentlessly, this entrepreneur who, from simple plasterer is now at the head of a flourishing construction company in Saint-Aignan, has continued to want to know the truth about the death of a girl. Is this a technical problem of the A 330 that caused the tragedy? A human error of the team of pilots of this transatlantic flight? Michel Mommayou did not wait for the two reports of judicial expertise to get an idea. With the support of his lawyer Jean-Lou Lévi, the contractor assembled a team to obtain his own expertise of the accident. Surrounded by a former Air France pilot, a former air traffic controller and a mechanic of the company, all settled in Castelsarrasin ... This trio of aeronautical experts spend months peeling, studying all data. They will go so far as to give justice the place, long unknown, of the crash. An incredible story that Michel Mommayou, who has also become an aeronautics enthusiast, unveils us today. An investigation that led him to an intimate conviction: the heavy responsibility of the commander of the AF 447. A thesis that the latest forensic expertise confirms to the chagrin of the president of the association of victims of the crash, Danièle Lamy . The latter hopes that this report essentially involving the pilots of Air France, exonerates neither Airbus nor Thales of their responsibility. Michel Mommayou has a different opinion ... Interview.

In contrast to the president of AF 447 - the association of families and relatives of the victims of the crash Rio - Paris - are you satisfied with the conclusions of the counter-expert report published last week?

When I read the report last Thursday, I was alone in the office of my company: I screamed, I cried! I have been waiting for that for almost nine years. I was afraid the truth would never break that it was stifled. With this counter-expertise, the investigating judge can not return to it.

For you there is no doubt it is a negligence of the drivers who is the cause of the crash?

I do not dispute that there was a problem with the probes (Pitot, manufactured by Thales for the A330). These were frosted and blocked for less than a minute. Many planes are equipped with these probes and they do not fall. Still, when the counter of your self loose, it is not for that that you necessarily end against a plane tree. What is certain is that the pilots and especially the captain were not up to the task. They were not able to cope with this incident and, more importantly, they did not divert early enough to avoid the storm cell on which the aircraft was heading.

How can you say it?

From the beginning of this business, I had the chance to know a former Air France pilot certified A 330 who is retired in Castelsarrasin. With my lawyer Jean-Lou Lévi, he has set up a work team in which we find a air traffic controller and a former Air France mechanic. They worked on the subject, sifting through the data, redoing the flight simulations, they came to the same conclusions as the counter-expert report that it was a pilot error and, above all, a carelessness. captain.

This is a serious accusation ...

It must then be explained why on the 9 aircraft that were in this sector, 8 were diverted to avoid the storm. Only AF 447 continued in this direction.

How do you explain it?

We have never heard of the pilots' briefing before take-off. This particular allows to check the weather ... Why? We simply doubt that it took place. It is a serious negligence of the Cdt especially in this intercontinental zone where it moves a lot. It is known that he slept only 1:30 the day before the flight. In the records of the black boxes, we hear him fourteen minutes before the crash telling his co-drivers: "You know what will happen in front of you (talking about the storm). I'm breaking myself (resting). " It is not because he is dead that he is not telling the truth. He has shown lack of professionalism.

What are you expecting now?

When the truth has exploded, I hope nothing more will happen, that the trial we all expect will take place. The experts who made these two reports agree ... Now it's enough!

The asso AF 447 is afraid that Airbus and Thales are not on the dock ...

My engine in this case: it's Virginia. My daughter would not let herself be done, nor me. The association since 2001, I do not belong there, I do not know where they are ... But we will not do an expert every two years. Stop!

[Mr Optimistic]

I suppose from my PAX view, given that everything has been hashed over so many times, looking back on it all, it was crew action that caused the zoom climb and crew action that failed to recover even though simulations showed recovery was possible with 10k ft loss. Elevator control was present despite THD at limit. No horizon, counter intuitive non-latching stall warning limit compound an erroneous mind set focussed on a presumed inability to stall but not in that control law. Actual control law and limited protections clearly displayed for eyes that looked and could focus. Bad day at the office, maybe bad night the night before.

[Winnerhofer]

https://www.aerotime.aero/en/civil/20246-blame-the-pilot-the-case-of-air-france-447

[jack11111]

From the article in Aerotime:
And there is another factor, which is also very important. One lawyer I spoke with, who is actually advising the families of the deceased people on the Air France crash, told me, there is a co-dependent relationship between these organizations and the big airplane constructors.
(my bold, underline)

I think the author may have a conflict-of-interest.

He believes the software that controls the pitot heads maybe faulty?! Also states that because Airbus made changes to their software proves they thought it was faulty. This is what lawyers always seize upon.

[Winnerhofer]

https://www.flightglobal.com/news/articles/in-focus-after-af447-what-now-377433/

[fizz57]

The point of linking to an article published in 2012 being?

[KayPam]

Does anyone here know about Norbert Jacquet ?
He's a French pilot who's, to say the least, against the concept of fly by wire.
He commented extensively on previous crashes, which, according to his own website, led him to be sacked by Air France (where he was a boeing captain)

He's got a website here, you can use the english flag or google translate to read it.
Airbus - The lies / by Norbert Jacquet (http://jacno.com/za-an-inmo.htm)

I really don't know what to think about all of this

[infrequentflyer789]

Does anyone here know about Norbert Jacquet ?
[...]
I really don't know what to think about all of this

My 2cents, probably worth less: It is fairly simple really, he is either a mentally ill conspiracy theorist, or he is an outstandingly persistent whistle-blower fighting against an entire system including his own lawyers to bring to our attention the dangerous flaws in Airbus' FBW systems (and/or FBW in general).

The problem with the latter view is that FBW Airbuses have been flying now for 30 years and are not obviously falling out of the sky at a greater rate than non-FBW airliners - you can slice and dice the stats a million ways, there is no signal that stands out from the noise or isn't more than covered by correlation with other variables.

It is still possible that FBW has had some effect on safety, good or bad, but there are other far more important things that have happened in the same time frame - EGPWS and TCAS for instance. If choosing flights (as pax) for safety, airline / operator, region and airports may be far more important than A or B (certainly easier to get a idea from the stats) - for instance I personally would avoid Air France before I avoided Airbus...

The most telling thing for me though is that behind all the fuss about airbus fbw, FADECs seemed to sneak in without a murmur. Yet many/most of the arguments against also apply there (e.g. there are 100k+ lines of code in typical FADEC, maybe far more these days, and as far as I know they are the same lines of code on each engine, and if "computer says no", it don't go - whatever type of thrust levers you have).

Norbert Jacquet seems to have very little to say about FADECs, possibly because he doesn't have that much of a clue, or possibly because Boeing uses them too - doesn't inspire any confidence in his output either way.

[KayPam]

This post was a real grammar exercise for me because everything is written in the conditional tense !

He points out very troubling things regarding the Habsheim accident.
He shows pictures and newspaper articles for both of the following :
- The pilot (Asseline) would have received not one but two fake licenses, after his license was confiscated (by the same authority)
- The black boxes would have been tampered with by the BEA, and they would even have given the judiciary investigators fake blackboxes (he shows pictures with different marking patterns on the black boxes)

He also says things very troubling about France :
- He would have been declared mentally ill by state doctors, whereas private doctors signed several certificates saying he was not crazy*
- He would have been followed and threatened by state agents**
- He would have been forcefully sent to mental asylums even though he was not crazy*
All that because he said things that were obviously causing a trouble.

*Of course, staying focused on the same topic for 30 years despite all the problems it caused him is the sign of a slight deviation from the norm. But not the kind of deviation that would justify denying him his medical, or sending him to an institution.


Like you said, today, it certain that FBW is not outright dangerous in itself.

So I think we can conclude that one of several hypotheses is true :
1 - The Habsheim crash revealed a small defect with the 320 (either the normal law, or the fadec, or the engine itself..). Jacquet was too much of a pain in the ass, so the state decided to shut him up. Then even though the 320 problem was solved (with a simple software update), the man never changed his mind. At this stage, his mind and jugement could also have been polluted by several years of fighting against something he cannot beat (the state and airbus), and it's plausible he won't support any airbus system for the rest of his life.

2 - Or, there was never a problem with the 320 to begin with, and the state just destroyed this man for no reason.

3 - Or, everything could be made up bull****, but that seems improbable since there are many articles proving at least 2.

**You can google things like "rainbow warrior" to find that the French state was not always "white as snow" as the French saying goes.

[SPA83]

Can pilots be asked to perfectly control a trajectory without speed indications with a non-compliant airplane with the regulations of the certification basis (no static longitudinal stability and no low speed protection)?

[Chris Scott]

Can pilots be asked to perfectly control a trajectory without speed indications with a non-compliant airplane with the regulations of the certification basis (no static longitudinal stability and no low speed protection)?

Hi. Presumably you meant to say "... an airplane non-compliant with the basic certification regulations (no static longitudinal stability and no low-speed protection)." ?

Am not conversant with the contemporary certification requirements affecting the A330-200 but, as far as I know, the A330 does enjoy static longitudinal stability. As for low-speed protection, that had become ineffective or spurious on AF447 only due to a significant system failure, so I don't see in what way the aircraft type could be considered non-compliant.

Regarding the PF's task - in the sudden absence of reliable airspeed indications - of maintaining straight-and-level flight, together with a suitable thrust setting: that matter has been discussed at considerable length in the pages of this thread and its predecessors.

EDIT
Further to the issue of longitudinal stability (see above) and the handling qualities available to the PF after the effective loss of airspeed indications, some readers may not be aware that the FBW had downgraded from Normal Law to Alternate Law in pitch, with Direct Law in roll. Although several pitch-related protections were lost, the feel and handling of the aircraft in pitch, known as C*, would have been identical to that in Normal Law. (The same cannot be said of the handling in roll.).

The aircraft's aerodynamic longitudinal stability would only be a relevant issue if the FBW had downgraded further to Direct Law in pitch. It did not.

[Winnerhofer]

Airliner pitot tubes provide redundant inputs for indicated airspeed and altitude readouts as well as inputs to all the various computer systems used for flight management. GPS provides groundspeed and GPS altitude information independent of pitot tubes. Angle of attack vanes provide angle of attack information (AOA) - a plane will not stall/spin if it is flying at less than stall angle of attack. As a retired Navy carrier pilot who used AOA exclusively for carrier approaches and didn't even scan airspeed except for a crosscheck at the beginning of an approach, I have always questioned why airline pilots aren't trained to use AOA and GPS speed readouts whenever any questions arise about pitot static systems reliability. AOA/GPS may not be accurate to the knot (groundspeed is a function of variable windspeed and direction) but they will both keep you comfortably within stall margin. Another mystery of life - why do folks who have no clue about aviation and aerodynamics feel qualified to display their ignorance on TV or in forums like this?

Angle of Attack. It would have saved the Air France flight had pilots been trained to it too. AOA is the only thing that matters regarding wing stall and insufficient lift. It’s been around longer than airspeed measure, too. I believe the Wright brothers did it with a piece of yarn compared to a mark though they had pusher props. Flight control computers use AOA at relatively low speeds and Mach at higher speeds. It’s time we stop teaching airspeed and teach AOA. AOA is consistent no matter the weight load or angle of bank. While not familiar with the 737, I’ll bet it had AOA.

As a active commercial pilot for a large airline and a retired military pilot (20+) year flying fighters I want to throw in my 2 cents. In every military aircraft I've flown there is a AOA (Angle of Attack) indicator. Most commercial aircraft do not have this indication available to the pilot which shocked me when I started flying for the airlines. The data is provided to the flight computers but not displayed the the pilot in what I've experienced. If you lose airspeed indication then defaulting to the AOA indication will prevent you from entering a stall. Air France flight 447 that crashed into the Atlantic Ocean killing 228 passengers in 2009 could have been saved if the pilots had AOA indictions. Their pitot system experienced icing temporarily kicking off the automation. Inexperienced pilots put the jet in a full stall from 38,000' until impact. The FAA needs to mandate all air carriers have an AOA indication in the cockpit and ensure pilots are trained to use it. Secondly, many of these foreign carriers just don't have the quality of pilots we have here in the US coupled with the fact that there is a pilot shortage world-wide.

The account of the Air France tragedy that I read in Vanity Fair was rather damning for the captain (who did have a lot of experience). He apparently had spent the day golfing and perhaps partying a bit with his GF and seemed more intent on staying out of the cabin and trying to get rest during the turbulence--which did leave younger pilots in charge of the flight. I asked my now late father (10 years USN; 25 years Pan Am) before he passed if he thought 447 could have been saved. He sighed and said "if they [pilots] understood exactly what was going on". He further explained that hand flying a sweep wing jet is very difficult without reliable instrumentation or a visible horizon (447 was a redeye) and that the "coffin corner" (approaching the speed of sound w/o reliable air speed readings) is something that is real. He also told me that if rough weather hit during one of his rest periods he would always end it and go into the flight cabin.

[PickyPerkins]

Winnerhofer. ... As a active commercial pilot for a large airline ...

Why does your public profile show you as having no flying license and no current type?

[Winnerhofer]

Would Air France AF447 have happened with Boeing? On June 1, 2009, Air France flight 447 from Rio de Janeiro (Brazil) to Paris (France) suddenly entered an aerodynamic stall and crashed into the Atlantic Ocean, killing all 228 passengers and crew onboard. Although the initial reports on the possible causes of the disaster evolved around the malfunction of the plane’s pitot tubes, the investigation concluded that the main reason for the tragedy was pilot’s mistake.It is often debated whether the accident of Flight AF447 from Rio to Paris was partly a consequence of the Airbus flight controls. No linkage between sidesticks, lack of feedback, a deceptive Flight Director, auto-trim and a flawed stall alarm. Two Air France Captains share their opinions. One of them is Gérard Arnoux, now retired, who for many years flew Airbus 320 for Air France and is now a technical advisor in the criminal court case. The other captain, who prefers to remain anonymous, flew Airbus 320 aircraft for many years and is now currently commanding a B777.The Boeing 777 is known as the competitor of the A330 and is also a fly-by-wire aircraft. What’s the difference?

Air France B777 Captain: On the B777 we have fly-by-wire flight controls but Boeing philosophy is different from Airbus. On a Boeing you see the input of the other pilot on the flight controls, as you see the autothrottle inputs at a glance. On Airbus you must search for information. For the throttles you have to “read” engines N1 (rotation speed in %) like you would read a digital clock.Having a yoke with physical feedback is quite different than having a joystick...

Air France B777 Captain: A Boeing-777 will always give you a physical feedback of your pilot action and physical evidences when your pilot actions are wrong. On Airbus the G-load piloting law erases a lot of that physical feeling.The G-load piloting law is why the Airbus is so easy to pilot when everything goes right, because the aircraft is always in trim, and you realize it’s like you would pilot through an autopilot: just look at flight director and make corrections through small inputs and that’s enough. I have flown the A320-family and it’s very easy to fly once you have understood that your inputs, with your wrist on the joystick, must be very accurate and minimal. The less you touch, the better it works. When you are very gentle and accurate on the stick, it’s a pleasure to see it flies alone. You can’t do that on Boeing 777.Until something goes wrong. Like unreliable speed readings, for instance...

Air France B777 Captain: You must know that training on speed failure in a simulator was very rare and during my 25 years practice on French airlines − before 2009 − I must have been trained maximum 3 times in a simulator for this situation, while we were having at least 2 engine failures to deal with at every simulator session.I do not know why speed failure was not trained. This kind of failure can be very stressing when at the same time you have overspeed warning and low speed warning, even stickshaker… The basic principle is to do nothing, just keep your thrust and attitude parameters of the aircraft. In the early years of the A320 we still had an incidence-meter (angle of attack meter, not installed on the A330) but still it is not easy and to rely on instruments, when real and false alarms are raised together.On Flight AF447 the pilots should just have kept on flying level flight, which they didn’t. Erroneous readings on their instruments, like the faulty Flight Director, which gave the order to pitch up.

Air France B-777 Captain: After the AP disconnected, the FD reappeared in basic mode, which is really not a good thing because the basic mode is just a copy of what you were doing when you connected the FD. They were climbing then, so the FD connected in Vertical Speed mode and told them to climb!Also, it seems that before the AP and AT shut off, the crew had just reduced speed to “turbulence speed”, a second before the autothrottle disconnected, so the thrust was less than the thrust needed to level flight... and the co-pilot pulled the joystick not having the right thrust.Another important factor to understand the accident is how Airbus auto trim works. As the co-pilot pulled back on the stick, the pitch trim helped him going backward to trim the aircraft because the computer acts as if Bonin* wanted the speed as low as possible... The pilots were not aware of the fact that the pitch trim was trimming all the way back, because on an Airbus you don’t have an artificial feeling, no stick shakers. They should have read the pitch trim indicator, which is something you forget to do on an Airbus, because it’s always in trim! They also should have had a visual warning telling them to use the pitch trim manually (Man pitch trim).The design of Airbus sidesticks and the fact that they are hidden for the other pilot, has been much criticized, even by an Airbus-man as Captain Sullenberger. Why is this still like that?

Gérard Arnoux: It is strange, but it is part of Airbus design philosophy and they won’t change that, even after AF447. I have read that recent aircraft by Bombardier and Embraer have active sidesticks. On Airbus there is no feedback and no linkage between the joysticks. Airbus doesn’t do that. It’s something dogmatic.There has also been a lot of criticism on the dangerous logic of the autotrimmable THS (Trimmable Horizontal Stabilizer), even when the plane is in Alternate Law. It induces the pilots to leave the protective flight envelope. The pilots did not feel that they were too pitched up, because they had no feedback on the joystick.

Air France B-777 Captain: On a Boeing you could never have done such thing (pulling on the flight control too much), because the pitch trim does not trim anymore when you approach stall speed, leaving flight controls harder and harder, as long as you are in Normal Mode (“Normal Law” on Airbus).On a Boeing, in Secondary Mode there is no stall protection either, but even in this law, a pilot trims with physical feedback. That is why, on a Boeing, you cannot stall without being physically aware of what is going on. It looks much safer to me.On AF 447, the only way to recover from the stall would have been to push on the stick for more than 30 seconds to allow the trim to set itself at the right setting to help the aircraft to recover! This is not intuitive at all.Have Flight Director flaws been addressed since and fixed on the current A330’s that are still flying around?

Gérard Arnoux: Flight Director which shut off and reappeared, displaying wrong information, has been fixed. There have been 4 Airworthiness directives by EASA (European Aviation Safety Agency) from 2010 to 2012 that addressed this problem and now Flight Director does not work anymore after unreliable airspeed situation.What about the stall warning which on the Airbus is inoperative under 60 knots. You called it “counterintuitive” in your legal report.I found it strange that legal experts did not mention it in their reports, because that is actually illegal. And as far as I know, the stall alarms on Airbus still don’t work under 60 knots, this hasn’t changed. It’s clear that Airbus completely underestimated this problem. Before June 1, 2009, the pilot-chief of training and flight at Airbus, Pierre Baud, stated in the in-house magazine FAST, that anti-stall training on Airbus planes wasn’t necessary.So why are there as many accidents on Boeing aircraft as on Airbus?

Air France B-777 Captain: Today pilots are assisted by so many systems that they don’t need to be so accurate, they do not need to be performing. We have been trained and recommended to fly on AP as much as possible, which is not a problem for a senior pilot like me. It can be a great problem for a young pilot that has become a «computer pilot» as if it was a game.Many companies do not allow their pilots to fly hands-on above 10.000 feet and a lot of airlines do not encourage visual approach and that goes not only for Airbus, but also for Boeing pilots.In the B777 Emirates accident in Dubai (2014), the pilots had an instrument telling them they were too fast, that’s why they pulled up, but in a bad way because they forgot to push the throttles. Old pilots always push their throttles when pulling up. They probably could have stopped the aircraft before the end of the runway, which does not mean pulling up was a bad option.In the San Francisco B777 crash (2013), four experienced pilots crashed in fine weather because they were relying on their autothrottle. As the majority of pilots now, they never use manual throttle because it is not encouraged, so they feel uncomfortable to disconnect. These Pilots were supposed to obey systems that have been implemented for safety purposes. They’re becoming kind of Pavlov’ pilots.Automation is becoming a risk factor?

Air France B777 Captain: I had a very interesting B-777 simulator session last week with the Traffic Collision Avoidance System (TCAS). I was on a collision course with another aircraft I was seeing. There was a TCAS-alert and I was waiting for a TCAS-command, because the aircraft’s computers “talk with each other”. So I was awaiting this order to disconnect the Autopilot and Autothrottle and fly the avoidance order but the command never came, due to a bug.At the very last moment I decided to disconnect and did a brutal manoeuver to avoid the colliding aircraft. I realized that I expected too much from computer systems and it was a good lesson of what happens when the computer fails.So the conclusion is that there should be limits on automation

Air France B777 Captain: There are two paths the aviation industry can take from here: One path would be more computers, better autothrottles, better autopilots, and more systems to detect whatever mistakes pilots make. Another would be to train pilots to fly manually and learn to avoid errors.In the first case, you do not need any more pilots and there always will be crashes. The computers will only prevent crashes imagined by engineers. A computer will never decide to do what Sully did with his A320 on the Hudson.People talk about pilot errors, but never about pilot solutions, which save lives by not following the checklist, like Captain Champion de Crespigny who flew Qantas Airbus 380 with 469 people to safety in 2010, after an uncontained engine failure, fuel tank leak, hydraulic failure, etc.Computers in aircraft are a good thing, as long as they serve pilots and not the opposite. Maybe I am wrong, but I feel safer in a Boeing, which is like a big solid truck with Apple computers you can disconnect, than in an Airbus, which is like a Space Shuttle with PC computers that have the last word. With Boeing, average or tired pilots will do the job, with Airbus you need the best, it’s not optional.

[Winnerhofer]

This article was cut and pasted by Winnerhofer from some other web site. It has been cleaned up to improve readability. The original work was compiled by Richard J. Ranaudo. (Mod)
Increasing automation has introduced new situational awareness challenges for pilots.
Increasing automation has introduced new situational awareness challenges for pilots.

We’re going to crash! … This can’t be happening!”

These were the last words of the first officer as Air France Flight 447, an Airbus A330, crashed into the Atlantic Ocean on June 1, 2009, killing all 228 persons on board.1 During the final minutes of the flight, the cockpit voice recorder painted a picture of confusion and frustration in the cockpit, likely due to the crew’s inability to understand what was happening.

The Flight 447 accident, according to the findings of the French Bureau d’Enquêtes et d’Analyses (BEA)² was precipitated by loss of three sources of airspeed indications at high altitude due to blockage of the pitot tubes by ice crystals. Subsequently, the fly-by-wire flight control system went into a degraded mode, and the autopilot disconnected, likely startling the pilots.

This required manual handling of the airplane at high altitude — a requirement for which the pilot flying (PF) had no prior training. The PF began a climb to a higher altitude and unknowingly stalled the aircraft. He continued to make inappropriate control inputs until it crashed.

Among the accident’s causal factors, the BEA cited the “ergonomic features” of the warning system design and the manner in which pilots are trained for stall conditions — using methods that would not elicit the appropriate response behaviors in this situation.

In its findings, the BEA stated: “The crew, progressively becoming de-structured, likely never understood that it was faced with a ‘simple’ loss of three sources of airspeed information. In the minute that followed the autopilot disconnection, the failure of the attempts to understand the situation and the de-structuring of crew cooperation fed on each other until the total loss of cognitive control of the situation.”

The crew’s loss of situational awareness (SA) began a chain of events resulting in the accident.
Airmanship and SA
Airmanship skills are defined more broadly as “the consistent use of good judgment and well-developed skills to accomplish flight objectives. This consistency is founded on a cornerstone of uncompromising flight discipline and is developed through systematic skill acquisition and proficiency. A high state of situational awarenesscompletes the airmanship picture and is obtained through knowledge of one’s self, aircraft, environment, team and risk.”³ Maintaining SA in today’s modern transport aircraft requires attention and cognitive skills to sense and process information in a timely and accurate manner. Older-generation aircraft required a focus on motor skills, but modern, highly automated aircraft require more focus on attention and cognition skills.

According to a recent U.S. Federal Aviation Administration (FAA) report on human factors: “Highly automated systems in which the flight crew serves primarily as a monitor may reduce their awareness of system state, leading to longer response times in emergencies and loss of knowledge or skill. Additionally, humans are traditionally poor monitors, and as time spent in a purely monitoring mode increase[s], the ability to remain attentive decreases dramatically as does (their) performance.”4  The transport aircraft accident rate since the introduction of more automated aircraft systems in the 1980s continues to decrease, as shown in International Civil Aviation Organization Document 9683/950, Human Factors Training Manual, and illustrated in Figure 1. While automation has improved safety and reliability, it has introduced new and different challenges to achieving the goal of safe flight operations.5 Stated another way, when it comes to human error, automated systems have not eliminated it, they have relocated it.
Figure 1 — Accident Rates After Introduction of Automated Aircrafthttps://flightsafety.org/wp-content/uploads/2019/01/humanfactors_dec18-jan19_fig1.svg
Source: International Civil Aviation Organization and Boeing

Limits of Human Information Processing
Humans are essentially limited-capacity, single-channel operators, which means that we are serial processors and cannot attend to independent input and output activities simultaneously without suffering a performance loss on other tasks.6Human limitations in attention and memory resources, especially in a high workload or stressful situation, can have a detrimental effect on achieving good SA. Mica Endsley, a noted human factors expert in SA, defined three levels or stages required to achieve good SA: Level 1 — Perception of the Elements in the Environment, Level 2 — Comprehension of the Current Situation and Level 3 — Projection of Future Status.7 These stages can also be mapped into the stages of human information processing (Figure 2).8Figure 2 — Information Processing Modelhttps://flightsafety.org/wp-content/uploads/2019/01/humanfactors_dec18-jan19_fig2.svg

Source: Ranaudo, R., University of Tennessee Space Institute. “Human Factors” course notes, adapted from Wickens, C.D.; Flach, J.M., Human Factors in Aviation, Ch. 5, Academic Press, Inc., 1988, Editors Weiner, E.L.; Nagel, N.C.

SA begins with a perception of a stimulus (visual, auditory, somatosensory, etc.), and proceeds to higher levels of cognition. As shown in Figure 3, working memory, which is a component of attention resources, is called upon to assess what is perceived, and may extract information from knowledge, experience or training stored in long-term memory to define the situation and decide what action or actions are required. Based on the result of the action, and the expectation of its outcome, a determination is made either to be satisfied with the result or to seek more cues and repeat the cycle. What are not in this simplified model are effects of stressors such as time compression, confusion and emotions resulting from fear or difficult interactions with others in a team process. Further complications occur when this process is incited by a surprising or startling event. Startle and surprise, however, are terms that are frequently and incorrectly used synonymously. In reality, they are different events with different responses having different causes and effects. A startle occurs quickly, as a result of an unexpected event such as a pistol shot or the blast of a loud horn and elicits a physiological reaction — eye blinks, muscle tightening and elevated heart rate. Surprise, on the other hand, occurs when something does not react or behave as expected, such as a failure annunciation of stall warning when such a failure is not expected.

A confusing automation behavior is a common source of surprise in modern aircraft. Surprises generally manifest themselves in subtle ways, such as discovering a slow loss of cabin pressure; however, surprises can also follow a startling event. “These events are known to interrupt information processing to the point where the selection and execution of actions become reactive and sequential instead of anticipatory and proactive,” according to a 2017 report.9 “Tunnel vision” can then occur, causing a cognitive lockup. Quite possibly, this explains the continued incorrect pitch inputs by the PF in the Air France Flight 447 accident; as the BEA said, “The excessive nature of the PF’s inputs (in a stalled condition) can be explained by the startle effect and the emotional shock at the autopilot disconnection.”

Training for Better SA
The capacity for attaining SA varies among individuals. The reasons are complex, involving differences in cognitive capabilities, combined with knowledge and experience gained throughout life. Nevertheless, some people are much better at SA than others. These individuals also tend to be better at observing and extracting information from their environment, situation or activity. They direct their attention resources more efficiently, remain focused on their goals and ignore distractions. According to Endsley, 88 percent of accidents involving pilot error are due to problems with SA.10 She also believes that acquiring SA is a trainable skill11 and identifies 12 key principals around which SA training programs should be built. They include a host of key behavioral skills such as task management, comprehension, projection, attention sharing, team skills and forming mental models of systems and environments. This training would ostensibly transfer to better SA skills in the cockpit.

Michael Gillen, airline pilot and human factors expert, studied 40 airline crews receiving targeted training designed to mitigate startle and surprise. The research was conducted to assess training effectiveness in both high- and low-altitude scenarios using a Level D flight simulator. The thrust of the training was to enforce call-outs to identify and stabilize an undesirable situation. In an article summarizing the results of his research that appeared in the November 2017 issue of AeroSafety World (ASW),12 Gillen said, “The most significant factor in determining scenario success was problem identification, which was consistent with previous research (showing) when crews make an initial wrong decision, the in-flight issue tends to rapidly degrade.” He added, “The data showed that targeted training can help pilots bridge the cognitive gap when startled, and the fact that trained crews performed equally well in both (high- and low-altitude) scenarios suggested that the training had a broad array of effectiveness.” Gillen believes that startle can be mitigated with behavior-based training. The ASW article was based on a presentation Gillen made at Foundation’s 70th International Air Safety Summit in Dublin in October 2017.

Specific training requirements for airline pilots are found in U.S. Federal Aviation Regulations (FARs) Part 121.13 These training requirements are usually well scripted, involving standardized and relatively predictable scenarios. This type of training, which is termed “brittle,” does not require flight crews to have a high level of SA and may not transfer well to novel and unexpected emergency situations.14 As a result, pilots generally know what to expect during a check ride. At the highest level of information processing, SA is achieved in a perceptual cycle that evaluates and re-evaluates a problem. This high level of processing can come through training, which is why accident investigators in recent years have proposed changing the airline pilot training requirements to include more random and unexpected scenarios. A 2018 report summarized a research program conducted by Delft University, Netherlands, to determine if exposing pilots to unpredictability and variability (U/V) in training scenarios would improve their response performance to startle and surprise events. The test was conducted with 20 experienced airline pilots. A Delft research simulator, shown in the photo below (Figure 3), with a full motion base, visual display and a hybrid aircraft model, was used.Figure 3 — Delft University of Technology “Simona” Research Simulatorhttps://flightsafety.org/wp-content/uploads/2019/01/humanfactors_dec18-jan19_fig3.jpg
Source: Courtesy, Olaf Stroosma and photograph by Theirry Shut, Delft University of Technology

The pilots were divided into two groups of 10 — a control group whose members were given non-variable and predictable training, and an experimental group whose training was U/V. A hybrid aircraft model was in the simulator, for which none of the pilots had previous experience. Variability was achieved for the U/V group by alternating the failure conditions from run to run, whereas the control group practiced the failure cases in succession (non-variable). Before a practice run, the U/V group was only told that a malfunction would occur (unpredictable failure), but the control group was told the details of what to expect (predictable failure).

After the practice sessions, the pilots in both groups were tested in identical failure scenarios that were designed to create surprise or startle. Surprise was caused by engine and control system failures. The presence of startle was assessed post-test with Likert-type opinion questions — for example, “How startled or shocked were you when you discovered the issue?” (1 = not at all, 5 = extremely). The test profile is shown in Figure 4.Figure 4 — Traffic Pattern Flown in Surprise Testhttps://flightsafety.org/wp-content/uploads/2019/01/humanfactors_dec18-jan19_fig4.svg
1. Right engine loses power over 20 seconds.
2. Brief decrease in left engine power, which was restored immediately.
3. Rudder effectiveness decreases 20 percent.

Source: R. Ranaudo, Adapted from Reference 12.

A moderate nearly direct crosswind was present, and pilots were told to fly a left traffic pattern and call out failures as soon as they became aware of them. A successful landing was the success criterion. The test profile began with a right engine power loss on takeoff at 55 kt (1). After the callout (or after approximately 30 seconds), pilots were instructed to continue the takeoff and were given a lower level-off altitude. A second surprise was an engine power loss after which the pilot was informed that both engines were unreliable but still running (2). When turning downwind, rudder effectiveness was reduced by 20 percent (3). A successful landing was possible only if pilots identified the failures and managed differential thrust to offset loss of rudder effectiveness. The U/V pilots adapted their training and developed a control strategy allowing them to fly a steeper approach with reduced thrust on the good engine and landed safely. Successful landings were made by nine of the 10 pilots in the U/V group and only two of the 10 pilots in the control group. Callout times for failures were not significantly different between the two groups. Regarding the subjective determination of startle vs. surprise from the opinion questionnaires, there was no significant difference between the groups. On a scale of 1 to 5, startle was rated between (slight) 2 to (moderate) 3. Surprise was rated on average a (moderate) 3, with the highest (very) 4 for all events. Overall, the U/V group rated all events as “significantly easier to understand” than the control group. The higher surprise ratings indicated that the failure events were unexpected but not of such significance that the pilots felt threatened. Real-world conditions would likely have caused higher ratings.

Changes in Training
Following the Air France Flight 447 accident, the BEA recommended that unexpected and unusual situations — that is, surprise and startle events — be incorporated into pilot training scenarios. This training takes a behavioral approach that emphasizes problem solving through analysis of failure indicators and their meaning. The objective is to teach pilots how to make sense of a novel or unusual situation, achieve good SA and make better decisions and action responses. The results of the two studies cited in this article give evidence to the efficacy of this training. But completing the picture requires that training include manual control skills training in failure modes. These are still the most basic airmanship skills required of a pilot.


Richard J. Ranaudo was a U.S. National Aeronautics and Space Administration (NASA) research pilot for 25 years and the lead project test pilot in the icing research program for 16 years. After retiring from NASA, he spent five years as manager of Canadair flight test programs, and conducted icing development and certification testing on prototype business and regional aircraft. As a research assistant professor at the University of Tennessee Space Institute, he taught graduate level courses in the Aviation Systems Program, including human factors in aviation, flight test engineering and airport systems.

[safetypee]

Winnerhofer,
The debate is little more than A vs B separate from the root cause of the accident.

The simultaneous malfunction of three identical sensors confused a triple cross monitoring system resulting in an extensive and complicated disruption to normal flight deck displays. The type of sensor has been changed.

With a similar high-level systems view, the recent 737 accident appears to involve a single sensor failure and a weakness in the implementation of a dual cross monitoring system. The result was similarly confusing, with conflicting indications.

Thus these accidents - root cause systems malfunction, are conceptually very similar, if not identical, both unfortunately with the same outcome.

Outcomes, accidents, fatal or otherwise, should not be use to judge the relative merits amongst similar or dissimilar aircraft types.
If comparison is warranted, there would be greater benefit in assessing normal operations, the systems which aid safety or clarify situations, and protect pilots from ‘themselves’.

We should also recognise the problems in adapting ‘facts’ to fit a particular argument.

[llagonne66]

Oups, sorry Mods but we clearly have here a flagrant case of flogging a dead horse :rolleyes:

[Winnerhofer]

The most seminal crash ever supplanting SR111.
The case is yet to come court and with the social mayhem that rocks every France evert Saturday, at earliest will be in 2020!
A top French attorney told me (not specifically about AF447) that the longer a case gets to court, one forgets why one is in court!
Doubtlessly, the media frenzy will return and the question of Bonin's frozen licence will come to the fore as AF still refuse to release his payslips as to whether or not they tally.
An angry Father will not concede on the aforementioned.
Ipso facto, 11 years is too long and AF447 now resembles a cold case.
The pitots froze for 2 minutes but the wheels of justice still can not get any traction.
2020 is just the start but with appeals we are looking beyond 2025 not surprising that France's budget for the justice system is 1% GDP being the lowest of any G7 member.
When an air crash happens, it reflects a nation's status.

[Lonewolf_50]

Oups, sorry Mods but we clearly have here a flagrant case of flogging a dead horse :rolleyes:
I would describe it more as "foaming at the mouth" or "throwing a handfull of spaghetti at the wall and see how many noodles stick."

Coherence, on the other hand, is a stranger to W's posts.
I dropped in to see if anything new was in the offing.
Not really.
gonebutnotforgotten
or as one wise ex-boss, and very good engineer, once told me, 'this [thing] is fool proof, but it's not bloody fool proof'. True of many aircraft. I may keep that one for future reference. :ok:

The question on this accident that concerns me most is:
Are lessons actually learned?
Is better training in play today for A330 pilots?
Do pilots better understand their aircraft systems?
Do pilots get more training time and flying time hand flying?

These would hopefully be worthwhile action items after the final report was produced.
When an air crash happens, it reflects a nation's status. I guess that the US needs to pull the plug and let itself drown in the Gulf of Mexico now that a 767 went down near Houston the other day. :rolleyes:
Valueless spluttering like yours adds nothing to a discussion among pilots.

[safetypee]

Lonewolf 50 et al, Re #1622: ‘The question on this accident that concerns me most is:’

Are lessons actually learned?
Depends on what is identified as a lesson and the willingness to learn.
You can always ‘find’ error, but what else might be learnt as meaningful action. Whereas the limits in certification processes - unforeseen weather threats, could be alleviated with more technology, triple systems become quadruplex (dual become triple), but at what cost.

Is better training in play today for A330 pilots?
After replacing the pitots (revised design) what do you train for, … recovery from a situation which should not reoccur.

Do pilots better understand their aircraft systems?
No, and with increasing complexity is unlikely to improve. Understanding complex systems and the consequences of rare failures challenge the fundamental limits of human performance; we are unable to deal with situations which machines cannot manage on our behalf - because we were unable to manage … …
Also consider ongoing social changes, less teaching of critical thinking, instant communication, the desire and expectation for instant answers.

Do pilots get more training time and flying time hand flying?
Why propose a ‘training’ solution for a problem which might not exist. Hand flying or not, the industry appears to be managing safety very well so far; … perhaps train for awareness, self management, and the avoidance of complacency, … if only we knew how.

[Winnerhofer]

Indeed.
Did you know that NONE of the BEA's recommendations have been implemented?!
A total disgrace!
So that means the accident costed hundreds of millions, 228 lives lost for nothing...

[testpanel]

What would you expect from the french?

[infrequentflyer789]

What would you expect from the french?

Most of the recommendations were to EASA and/or ICAO, so the implementation is not under the control of the French.

[safetypee]

Winnerhofer,
You may have overlooked section 5 ‘Changes made since the accident’ page 215.
Also, perhaps misinterpreting the context of a recommendation, including ‘review’ and ‘evaluate’.
The report is published according to ICAO Annex 13. Specific points can be directed to the aircraft certification authority, or the operations regulator; elsewhere a wider view is given e.g. EASA / FAA.

A significant weakness in the overall safety process is the time delay both in reporting and implementation, the judgement of cost effectiveness against the continuing risk (e.g. pitots fixed), or how to validate the effectiveness of intervention.

[Winnerhofer]

https://www.aerotime.aero/aerotime.team/21361-interview-would-air-france-f447-have-happened-with-boeing

Air France 777 captain appears to misunderstand how the Airbus works. His statement "how Airbus auto trim works. As the co-pilot pulled back on the stick, the pitch trim helped him going backward to trim the aircraft because the computer acts as if Bonin* wanted the speed as low as possible... The pilots were not aware of the fact that the pitch trim was trimming all the way back, because on an Airbus you don’t have an artificial feeling, no stick shakers."

Autotrim only serves to align the elevators with the stabilizer. In Normal and Alternate laws it has NO EFFECT on how the airplane feels or behaves. In the flight control law where AF447 found itself (ALT2) and the sidestick demands g-load. As a result, it's basically a point and PROT) the stick changes from g-load demand to full back law the hard protection is replaced (due to various failures) with a "stability", which is the airplane's natural aerodynamic stability to pitch down when very slow.

However, the transition from g-load to stability mode is based on indicated airspeed. In the case of AF447, the airspeeds were rejected by the flight control computers because it had become unreliable due to the pitot tube issues. This left the airplane in full-time g-load demand.

When at least 2 of 3 airspeed sources were deemed unreliable, the autopilot disconnected. This dropped the job of hand flying the airplane into the laps of the unsuspecting and very-soon-to-by confused pilots, when they least expected it, and probably least prepared to handle it. "Startle factor" is the term used here that describes their diminished mental capacity to perform.

He said "They should have read the pitch trim indicator, which is something you forget to do on an Airbus, because it’s always in trim! They also should have had a visual warning telling them to use the pitch trim manually (Man pitch trim)." This is not correct. At least not for the fist full minute with the stall warning going off. All they had to do initially was to point the airplane down. It did not require any trim action. Now later on, when the angle of attack was extremely high (>45°) and the trim was full nose up, my own tests indicate that manually reducing the nose-up trim may have been required for a successful recovery from the 20,000 ft/min descent they put themselves in.

But instead of nose-down input, which would have worked, they instituted the only stall recovery action they apparently remembered: full power. Except at cruise altitude, they were pretty much already af full power and the extremely minor amount of power still left would produce no results.

Unfortunately, Bonin's initial actions on the stick (be then intentional or as a consequence of something else) were to pitch the airplane up. But the airplane's neutral stability allowed the nose to just stay there.

It did not require trim to hold it there. That was its job. If he had pulled it back and then just let go completely, the result would have been much the same. The lack of the low-speed stability meant that as the airplane approached the stall AOA, there was nothing to pitch it down except the pilot - who was probably trying to follow the ever-reliable flight director which was telling him to continue the climb.

As the airplane began to stall and lose lift, the airplane started to sink, and thus the actual g-load was reduced. The airplane responded to this less-than-demanded g load with all it had at its disposal to increase the g load: Up Elevator. This obviously just made things worse and within a few seconds, the angle of attack increased to 45° and more (though the pitch attitude remained at 15° or less).

What this required from the start was for the pilot flying to FLY THE AIRPLANE. That is, command a pitch and power setting commensurate with level flight (2.5° & 83% N1). Any pitch and power setting remotely close would have kept the crew out of trouble for a long time. It only took about 40 seconds for all of the pitot tube issues to resolve themselves, and they could have been on their merry way like the dozens of other crews that employed that strategy in similar circumstances. However, by the time the pitot tubes were clear, the flight was in a far worse position, having climbed 3000 feet and lost over 100 knots of indicated airspeed. A recovery at this point required far greater skill than the minimal skill required to fly straight and level just 60 seconds earlier that they failed to exhibit.

It is further interesting to note that Airbus seems to have taken this accident to heart in the design of the A350. It has extremely robust airspeed backups (even if all pitot tubes become unusable), and Alternate law maintains all of the same hard protections as Normal law (assuming the physical flight control surfaces are not damaged beyond carrying them out). Further, the autopilot remains engaged in an extended envelope (right up to the abnormal attitude parameters (120° bank, 50° pitch, etc) So, in this case, the AP/FD would not have disengaged at all.

[Bidule]

Interest of quoting this paper almost one year after its distribution?

[gums]

Salute!

It's called ET 302 and serious Boeing problems.

Gums...

[Bidule]

Not sure that the causes of these two accidents are the same or even similar. In fact, I am almost sure that they are not for a lot of reasons, such as phase of the flight including altitude, day/night, mature aircraft ...

[alexd10]

.....Both with planes perfect flyable, both with banal sensor malfunctions, both with inappropriate responses from PF, both with crews untrained for those flight circumstances, both with manufacturers purposefully understating training requirements (do you remember the concierge ?) both with aeronautical authorities closing eyes at serious things for industry's sake......., and comparable number of deaths!

[seagull967]

It is my understanding that the A350 also no longer has the autotrim function in alternate law, is that correct?

[ATC Watcher]

I will not comment on the technicalities of both accidents , not my area of expertise. although looking from the outside that is a lot of preventable accidents happening due of the failure of one sensor , or of one instrument/IRU ( i.e west air sweden ) and inability of crew to recognise it.
Whether it is a design issue , a training one, or other I leave the discussion to you guys.
But on the French Judiciary system , I agree with W. it is a scandal . Last week the trial of the people responsible for the collapse of CDG Terminal 2E , took place, that is 14 years after the event !
The worse ( that i know of) is the UTA DC10 bombing/accident that took place in 1989 in the Libyan desert. The last appeal , closing the case was done in 2008 , almost 20 years after the event , and the suspected perpetrator , a Libyan national. received a pre-trial in Tripoli in 2013 , still awaiting the full trial, we are now 30 years later..

[Winnerhofer]

https://www.telecablesat.fr/actus/31/doc-mag/af447-la-traque-du-vol-rio-paris-10-ans-apres-le-crash.html

New documentary out on 31 May 2019

[Winnerhofer]

From AF447 to AI447
What if the cockpit stall warning had said, “Pierre-Cédric (the co-pilot primarily responsible for pitching the plane’s nose upward for the entire six minutes) you are ignoring my warning that the plane is in a stall and losing altitude. Please take immediate corrective action by pitching the nose down or give me control so that I can rectify the situation.”

https://www.innovationexcellence.com/blog/2019/05/15/lets-stop-calling-it-artificial-intelligence/

[Lonewolf_50]

From AF447 to AI447
What if the cockpit stall warning had said, “Pierre-Cédric (the co-pilot primarily responsible for pitching the plane’s nose upward for the entire six minutes) you are ignoring my warning that the plane is in a stall and losing altitude. Please take immediate corrective action by pitching the nose down or give me control so that I can rectify the situation.” They'd have all still died, since auto pilot was off due to airspeed unreliable .. pitot tube icing. So Pierre-Cedric "gives" the plane to an autopilot that has already gone on holiday.
W, sometimes I wonder if you only post after a few pints.

[alexd10]

They'd have all still died, since auto pilot was off due to airspeed unreliable .. pitot tube icing. So Pierre-Cedric "gives" the plane to an autopilot that has already gone on holiday.
W, sometimes I wonder if you onlly post after a few pints.

You on the other hand are a little malicious , since we all know very well that the autopilot it's only one of HAL's avatars on the flight deck

[Lonewolf_50]

@alexd10, there is no value accrued to encouraging a bloviating fool to post on Tech Log, but there may be some value in discouraging the same.

You get what you incentivize, condone, and encourage. Psychology 101.

(and yes, on the technical side, you are correct. Brevity in this case was being used to respond to low quality garbage.)

[Winnerhofer]

https://www.planetepluscanada.com/emission/PHIS22291/af447-la-traque-du-vol-rio-paris
Watched it last night.
Absolutely thrilling.
Most poignant moment: the faces of investigators listening to the DCVR.
Surreal...surreal!
They were shocked and just were stunned into silence...faces were contorted with angst forever etched in disbelief.

[Winnerhofer]

AF charged, Airbus no case to answer.
https://www.huffingtonpost.fr/entry/rio-paris-proces-pour-air-france-et-un-non-lieu-pour-airbus-reclame-le-parquet_fr_5d2ee388e4b02fd71ddcd16c?utm_hp_ref=fr-homepage

[saviboy]

https://www.planetepluscanada.com/emission/PHIS22291/af447-la-traque-du-vol-rio-paris
Watched it last night.
Absolutely thrilling.
Most poignant moment: the faces of investigators listening to the DCVR.
Surreal...surreal!
They were shocked and just were stunned into silence...faces were contorted with angst forever etched in disbelief.

The video is not available anymore. Any other place we can watch this documentary?

[Bidule]

AF charged, Airbus no case to answer.
https://www.huffingtonpost.fr/entry/rio-paris-proces-pour-air-france-et-un-non-lieu-pour-airbus-reclame-le-parquet_fr_5d2ee388e4b02fd71ddcd16c?utm_hp_ref=fr-homepage


Not sure. The news report the recommendations of the prosecutor but the investigating judges have the final word and can decide anything they want: all parties charged, all parties released or any mix (subject to a possible later appeal).

.

[Winnerhofer]

The video is not available anymore. Any other place we can watch this documentary?
Only clips for now:
https://www.youtube.com/playlist?list=PLdiyQQhuhMu03Cx-Qokg5ww4ls1Zxgrj5

[saviboy]

Only clips for now:
https://www.youtube.com/playlist?list=PLdiyQQhuhMu03Cx-Qokg5ww4ls1Zxgrj5

Thanks. seems very interesting. Hopefully, they make the whole thing available soon

[Winnerhofer]

https://www.youtube.com/watch?v=ZrtfUZRk5h4

[Winnerhofer]

https://youtu.be/Wnh_RhK4qas?t=422

[Winnerhofer]

https://www.airbus-win.com/wp-content/uploads/2017/11/airbus_stall_vl_mix.mp4

[Winnerhofer]

https://www.youtube.com/watch?v=bBgJhFQAqrM

[Winnerhofer]

https://globoplay.globo.com/v/7627502/

[Winnerhofer]

https://www.youtube.com/watch?v=uzxB-y-0N6Q

[CVividasku]

I don't understand how airbus allowed the PHR to trim itself up to full up.
There is no situation (apart from something very remote) in which this would be safe or even reasonable.
Every light GA pilot knows that you don't trim an aircraft below 1.3Vs...

This single feature caused at least to accidents and hundreds of deaths.

[CVividasku]

I forgot to mention that I watched the entire video above. This guy seems to come from nowhere but his analysis is one of the most accurate that can be found on this type of video. Only the official sources would be more precise, some of which are not available to the general public.

[Goldenrivett]

I don't understand how airbus allowed the PHR to trim itself up to full up. ...
This single feature caused at least to accidents and hundreds of deaths.
I disagree. The aircraft trimmed full nose up in response to the co-pilot's continuous back stick demand for more nose up.

One of the holes in the cheese could have been closed with "active side sticks" so that the other pilot may have recognised the gross handling error of constantly pulling back.

[Uplinker]

@ CVividasku; irrelevant. The "pilots" of AF447 caused the aircraft to crash - obviously not deliberately - RIP.

Hold full back-stick, or yoke in any aircraft, and it will stall. Keep holding full pitch-up during the stall and descent, and you will crash. The standard stall recovery is to immediately pitch down - this should be instinctive to experienced airline pilots.

Yes, the Airbus side-sticks are not easily visible to the other pilot, especially in dark conditions. I would add simple software to bring up the square ground control check display on both PFDs if a side-stick was held at or near a limit in flight for more than, say, a few seconds, so the other pilot would be alerted to what the first pilot was doing with their side-stick.

[CVividasku]

I disagree. The aircraft trimmed full nose up in response to the co-pilot's continuous back stick demand for more nose up.

One of the holes in the cheese could have been closed with active side sticks so that the other pilot may have recognised the gross handling error of constantly pulling back.
Active sidestick is not something new, Airbus could have coupled both side sticks easily, however it added some weight so I assume that was the main reason why they did not do it.

Yes, holding full back stick without a good reason and with no protection is stupid, but accompanying/encouraging/amplifying a stupid movement is stupid too, isn't it ?
Actually, there are two other important examples that show the error in Airbus design :
- The MCAS accidents (from Boeing) showed that uncommanded/uncommandable/hidden/insufficiently visible trim runaway is dangerous, but Airbus too is capable of surprising trim runaways.
(Actually, since Airbus hides in fact the entire THS from the pilot, if the pilot is made aware of a THS movement it is necessarily a surprise)
- The XL airways crash at perpignan showed the sheer danger of a fully upwards THS. Even with full down stick, they could not impose the correct trajectory on the aircraft.
Instead, the aircraft imposed them with a deadly climb up to more than 50° nose up pitch.

The THS, or more generally pitch trim, should only relieve the efforts on the stick. A correctly designed aircraft should (that's only my opinion as a pilot) always be controllable with a trim completely ran away in the wrong direction. And if that's not possible by the law of physics (as seems to be the case of the airbus) there should be serious measures to prevent this type of accidents :
- The THS cannot move to an area where the airplane won't be controllable in an automatic/hidden fashion, or
- The THS should revert automatically to a desirable position when the pilot applies large stick inputs that cannot be satisfied by the elevators only.

To me, this sounds like common sense.
Hold full back-stick, or yoke in any aircraft, and it will stall. Keep holding full pitch-up during the stall and descent, and you will crash. The standard stall recovery is to immediately pitch down - this should be instinctive to experienced airline pilots.
In the case of the XL airways crash, they applied full pitch down and would have been able to recover the aircraft in this dire situation, if only airbus had not trimmed itself automatically fully up.

Try to answer this question positively : is there any good reason to allow the THS to go fully upwards or fully downwards, in a way that will make the aircraft uncontrollable ?
Is there any good reason to allow the THS to go automatically and unknowingly outside of a safe zone that could be computed from the current CofG ?

[vilas]

When you pull or push the stick it is to change the attitude which you have to see on the PFD. 447 guy just pulled never looked at the pitch. They didn't see anything nor hear the stall warning. AT FL350 pulling 16° pitch is irrational. The pilots didn't know unreliable speed procedure and stall recovery procedure either. That may have triggered the fear factor causing loss of cognitive awareness. That's why all their actions appear irrational. Connected stick may have some virtue but if pilot doesn't know if pull is correct or push then it's not going to help.
Anyway ultimately the automation has come to rescue again. Now there's fourth source that is called Digital Back Up Speed it's calculated speed from load factor, CG etc. without any anemometric data that compares normal ADR speeds. Whatever is outside threshold is rejected through ECAM actions. If all are wrong then digital speed is displayed which you fly. In A350 it's automatically done. So no more 447.

[Bidule]

......
- The XL airways crash at perpignan showed the sheer danger of a fully upwards THS. Even with full down stick, they could not impose the correct trajectory on the aircraft.
Instead, the aircraft imposed them with a deadly climb up to more than 50° nose up pitch.
.........
In the case of the XL airways crash, they applied full pitch down and would have been able to recover the aircraft in this dire situation, if only airbus had not trimmed itself automatically fully up.


You should read the Accident Report for this Perpignan flight, which by the way was not a commercial flight. You will then see that it is much more complex than what you summarised to try supporting your views.

.

[Uplinker]

"(Actually, since Airbus hides in fact the entire THS from the pilot, if the pilot is made aware of a THS movement it is necessarily a surprise)"

The THS is not "hidden"; the trim wheels either side of the thrust lever quadrant clearly show any THS movement. Auto trim would not be a surprise to a properly trained Airbus FBW pilot.

Mechanically coupled side-sticks would need to have joints, bearings, levers etc, and would require a mechanism to uncouple the sticks, all of which could jam and cause more problems than it might solve.

Hence, if the side-stick position indication display - see below - that we use to check our controls before take-off were to reappear on both PFDs in the event of a stick being held at or near a limit in flight, then both pilots - and a third pilot - would be able to see on both PFDs what was happening. It would only take a couple of lines of extra program code in the software to add this feature.

From Airbus FCOM:
https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1402x1020/410f3c53_d280_48af_bd39_65b9fde212b6_3893660ecdbdb9a1678ca33 37f150f0362517472.jpeg

[Max Angle]

I could never understand why this is isn't a standard feature, the cross should be visible anytime the aircraft is being manually flown. Of course this would require Airbus admitting that the flight control system has a few shortcomings which they are never likely to do.

[iceman50]

No thanks, the "Bird" is available. Attitude is important not stick position. It has been removed earlier in the rotation by Airbus as it was being used as a rotation "attitude", which caused an interesting departure from J'Burg for one carrier.

[CVividasku]

When you pull or push the stick it is to change the attitude which you have to see on the PFD. 447 guy just pulled never looked at the pitch. They didn't see anything nor hear the stall warning. AT FL350 pulling 16° pitch is irrational. The pilots didn't know unreliable speed procedure and stall recovery procedure either. That may have triggered the fear factor causing loss of cognitive awareness. That's why all their actions appear irrational. Connected stick may have some virtue but if pilot doesn't know if pull is correct or push then it's not going to help.
Anyway ultimately the automation has come to rescue again. Now there's fourth source that is called Digital Back Up Speed it's calculated speed from load factor, CG etc. without any anemometric data that compares normal ADR speeds. Whatever is outside threshold is rejected through ECAM actions. If all are wrong then digital speed is displayed which you fly. In A350 it's automatically done. So no more 447.
Where did you see 16° pitch ?
I read 11°, which is still way too much of course.

In this accident, I think contrarily that too much automation is the cause.
Since RVSM, it is not possible anymore to hand fly at high altitudes. And how much sim time is there to train hand flying at altitude ? Maybe less than 10 minutes in the entire type rating and then less than 5 minutes every three years...
If hand flying at altitude was allowed, it would not have disoriented them that much.

Let's simplify the matter. Have you heard of a single GA crash where the pilot lost control, stalled or crashed, with no medical condition, in clear skies, while attempting to fly straight and level ?
Well I don't think so because flying straight and level is basic flying, which GA pilots are trained for and do all the time (most light GA don't even have an AP let alone FDs). Or if it happened, said pilot should never have gotten his license in the first place. But it's perfectly possible to have three full ATPL pilots with less than 3 hours (total) manual flying at altitude and 0 minute real manual flying at altitude in the aircraft.

Light aircraft do crash (even a lot) but for other reasons.
You should read the Accident Report for this Perpignan flight, which by the way was not a commercial flight. You will then see that it is much more complex than what you summarised to try supporting your views.

.
Can you tell me in which ways ?
I read the report, I know it wasn't the designed, nominal functioning of the airbus because the AOA froze, but the THS able to go fully up is nominal.
Here is a google translate from the report :
At 15 h 45 min 19, the stall warning stopped. The captain's longitudinal input is still full forward. The elevators reach their maximum nose-down position at approximately 11.6 degrees.
The bank was 40 degrees to the left and the Captain gradually canceled his lateral order. One second later, the aircraft is in a 7 degree pitch attitude. Its wings were close to horizontal and its speed was 138 kt. The Captain canceled his longitudinal order. At 15 h 45 min 23, the pitch attitude and altitude then began to increase. The altitude reached approximately 2,250 ft. The Captain immediately gave a longitudinal stop forward order.
With 7° pitch attitude, wings level, 138kt, TOGA. With a THS at neutral the aircraft is saved. With a THS fully up, 2-3 seconds without a fully down order on the sidestick killed them, with a 50° increase in pitch in less than 20 seconds.
On any normal aircraft, this pilot would have completed his test with no problem at all.
The pilot should have been made aware that his trim was doing a runaway.

My view is that the responsibility of the pilot does not exonerate the manufacturer from having to provide the pilots with an intuitive, safe aircraft, that won't do anything dangerous unexpectedly and with no information. In short, that is the contrary of MCAS style design. Am I wrong to think so ?

[vilas]

You should read the Accident Report for this Perpignan flight, which by the way was not a commercial flight. You will then see that it is much more complex than what you summarised to try supporting your views.

Perpignan was due to pressure washing of AoA probes which is not to be done. Water ingress into No.1 and 2 probes which froze at higher threshold after takeoff. No.3 which correct was kicked out by the rogues. Unscheduled last minute check of low speed protection with gear down airspeed reduced very low and when aircraft dropped wing it transitioned to direct law. The THS auto trimmed full up due to wrong SW threshold of 1&3. In normal law THS stops trimming at alpha prot.
Lastly 447 was beaten to death by 24000 posts on pprune. Nobody can discover anything new that wasn't already.

[vilas]

CVividasku
In 2006 or 2008 Airbus considered connected side sticks and didn't find it particularly useful and rejected it. In 2014 about the SFO crash NTSB asked Boeing to have look at their throttle hold function Boeing will keep looking but not going to do anything about it. High level handling is not possible because the planet is RVSM.
What is possible is to explain the pilot the normal attitudes at higher levels and tell him that at those levels in alternate law pulling on the stick without looking at PFD can be fatal. It is possible to teach him stall recovery as is being done. Tell pilots that even on autothrottle you cannot fly an approach without monitoring your speed. When automation reaches those perfect levels nobody will higher someone to sit in the cockpit. Already technology is moving towards that. It's matter of which is easier to eliminate, the human error or the human himself?
Already Airbus and Boeing have created a speed without anemometric input. Airbus calls it digital speed, Boeing calls it synthetic speed? That can be used in 447 situation. A350 has auto TCAS, auto EMER descent. It's not Airbus or Boeing it's the march of technology.

[pineteam]

The pilot should have been made aware that his trim was doing a runaway.


Any properly trained Pilots should notice if the trim is doing a runaway. It's barely moving in normal flight ( on A320 at least) and if for any reasons it's going crazy, it's easy to override it manually.

[CVividasku]

Any properly trained Pilots should notice if the trim is doing a runaway. It's barely moving in normal flight ( on A320 at least) and if for any reasons it's going crazy, it's easy to override it manually.
Really ?
I did the complete A320 TR and flew for only 4-5 minutes in direct law with man pitch trim.
Then I never had to worry about this wheel ever again.
I never had any trim runaway exercise or anything similar.

Plus, the wheel is not in the primary visual circuit, not even in the secondary visual circuit, and many accidents showed that it's not that easy to notice and override manually (Boeing had the same flaw with MCAS). And if you missed the movement, there is not a single indication that visibly indicates that there is something dangerous back there.

[Uplinker]

........In this accident, I think contrarily that too much automation is the cause............The pilot should have been made aware that his trim was doing a runaway...............My view is that the responsibility of the pilot does not exonerate the manufacturer from having to provide the pilots with an intuitive, safe aircraft, that won't do anything dangerous unexpectedly and with no information. In short, that is the contrary of MCAS style design. Am I wrong to think so ?

Automation is a fact of airline flying in today's busy airspaces. Going back to less or no automation is simply not going to happen. Pilots must only use the appropriate level of automation for the task, therefore pilots need to be properly trained how to understand and use the automation correctly. This is where a lot of problems seem to be arising. My classmates and I spent about 6 weeks in a classroom being taught about the Airbus FBW aircraft; followed by 4 weeks in the Sim; followed by 6+ weeks line training; followed by our final line check. Does this still happen, or is it a few days in front of a CBT computer before a reduced Sim and reduced line training?

The Airbus THS movement is clearly shown by the two black and white painted trim wheels.

After being type-rated on a number of conventional turboprops and jet transports, I found the Airbus FBW to be very intuitive - as long as you understand how the FBW works and how it helps you. I have observed some pilots who think it is fighting them etc., because they don't understand it.

Airbus FBW is a very good design and well engineered product - an order of magnitude better than what existed before its introduction. Nothing can ever be completely fool proof however, which is why the authorities rightly demand ATPL licences and type ratings - to ensure that aircraft are flown by capable professionals, not fools.

[pineteam]

Really ?
I did the complete A320 TR and flew for only 4-5 minutes in direct law with man pitch trim.
Then I never had to worry about this wheel ever again.
I never had any trim runaway exercise or anything similar.

Plus, the wheel is not in the primary visual circuit, not even in the secondary visual circuit, and many accidents showed that it's not that easy to notice and override manually (Boeing had the same flaw with MCAS). And if you missed the movement, there is not a single indication that visibly indicates that there is something dangerous back there.

Yes really. I mean on Airbus, if you release the side stick and the pitch is going up or down then there is a big chance it is related to the trim. I had a case while hand flying on the real aircraft that every time I was releasing the side stick the nose was going down. During the whole approach I had to keep constant back pressure similar like the flare mode but much less. I did not trim the aircraft manually cause I was still in normal law, aircraft still under control with light back pressure on the sidestick and no ECAM but I would definitely if it was a violent pitch up or down moment.

[vilas]

In Airbus computers are monitoring. Any uncommanded stab the ELAC will be knocked out and passed on to the next. There's simply no abnormality like runway trim. There's jam stab. Anyone who has done it in conventional aircraft knows how tough it is. Not so in Airbus because elevators are held in the given position.

[Goldenrivett]

Let's simplify the matter. Have you heard of a single GA crash where the pilot lost control, stalled or crashed, with no medical condition, in clear skies, while attempting to fly straight and level ?

On any normal aircraft, this pilot would have completed his test with no problem at all.
The pilot should have been made aware that his trim was doing a runaway.

My view is that the responsibility of the pilot does not exonerate the manufacturer from having to provide the pilots with an intuitive, safe aircraft, that won't do anything dangerous unexpectedly and with no information. In short, that is the contrary of MCAS style design. Am I wrong to think so ?

Would you call a B737-300 a normal aircraft? Would you think the crew of a B737 would recognise the pitch trim winding slowly backwards with the AP engaged on an ILS APP as the speed reduced? I suggest you read B737 GA at Bournemouth (https://assets.publishing.service.gov.uk/media/55265d3ded915d142a000018/Summary_-_AAR_3-2009_Boeing_737-3Q8__G-THOF_06-09.pdf)

"During the go-around the aircraft pitched up excessively; flight crew attempts to reduce the aircraft’s pitch were largely ineffective. The aircraft reached a maximum pitch of 44º nose-up and the indicated airspeed reduced to 82 kt. The flight crew, however, were able to recover control of the aircraft and complete a subsequent approach and landing at Bournemouth without further incident. "

Crews need to be constantly alert and not become "passengers" by assuming their aircraft will perform flawlessly every time.

[vilas]

The pilot should have been made aware that his trim was doing a runaway.
This was not a runway at all. It trimmed as designed. Airbus design the system trims for you. This test profile was only meant for a test pilot not a line pilot. That too the pilot suddenly decided to do it at low altitude without any briefing. When NO.3 ADR triggered a stall warning they should have abandoned the exercise. But they dropped speed below that. Even in alternate law if you don't keep back pressure on stick the nose will drop and it will stop trimming.

[Mr Optimistic]

[Pax] Have Airbus modified the stall warning logic, ie the blanket inhibition below 60kts ?

[Uplinker]

Really ?
I did the complete A320 TR and flew for only 4-5 minutes in direct law with man pitch trim.
Then I never had to worry about this wheel ever again. You should look for and notice the THS trim wheel movement during every flight. That and the speed trend arrow tell you what is going on with your aircraft.

Plus, the wheel is not in the primary visual circuit, not even in the secondary visual circuit, and many accidents showed that it's not that easy to notice and override manually........ Come on, both trim wheels are in plain view next to the thrust levers, they most certainly should be in your scan. To override THS trim you simply put a hand on a trim wheel and it will stop and the autopilot will disengage. And if you missed the movement, there is not a single indication that visibly indicates that there is something dangerous back there. There is nothing 'dangerous back there' to a properly trained Airbus pilot. I think you have been very badly taught the Airbus and also your scan needs revising and improving. I think your problem is with your 'trainers' not with Airbus design.

[CVividasku]

The THS is not "hidden"; the trim wheels either side of the thrust lever quadrant clearly show any THS movement. Auto trim would not be a surprise to a properly trained Airbus FBW pilot.

Mechanically coupled side-sticks would need to have joints, bearings, levers etc, and would require a mechanism to uncouple the sticks, all of which could jam and cause more problems than it might solve.

Hence, if the side-stick position indication display - see below - that we use to check our controls before take-off were to reappear on both PFDs in the event of a stick being held at or near a limit in flight, then both pilots - and a third pilot - would be able to see on both PFDs what was happening. It would only take a couple of lines of extra program code in the software to add this feature.


I think there is something inconsistent in what you're saying.
You're saying that the THS is not hidden, and that the trim wheels clearly show any THS movement.
But at the same time you say that the opposite sidestick is not visible enough.
In fact, the opposite sidestick is approximately as visible as the trim wheel, if not a bit more. It is in the peripheral vision, not in the primary or secondary visual circuit.

So I don't see why you would oppose making the THS more visible, while advocating for making the sidestick more visible.

I understand even less when considering that pitch control is achieved with both THS and elevators, trim wheel and sidestick.

Airbus FBW is a very good design and well engineered product - an order of magnitude better than what existed before its introduction. Nothing can ever be completely fool proof however, which is why the authorities rightly demand ATPL licences and type ratings - to ensure that aircraft are flown by capable professionals, not fools.
Reality is a bit different.
Airbus design directly contradicted the usual rules that existed before. And uncommanded THS movement is directly involved in this.
Aircraft are supposed to have a positive longitudinal static stability. Airbus FBW does not behave like that, "thanks" to THS moving automatically.
It has been deemed acceptable only with protections, and when those fail, you have an aircraft that would not be certified, with no information to the pilot.
Would you call a B737-300 a normal aircraft? Would you think the crew of a B737 would recognise the pitch trim winding slowly backwards with the AP engaged on an ILS APP as the speed reduced? I suggest you read B737 GA at Bournemouth (https://assets.publishing.service.gov.uk/media/55265d3ded915d142a000018/Summary_-_AAR_3-2009_Boeing_737-3Q8__G-THOF_06-09.pdf)

"During the go-around the aircraft pitched up excessively; flight crew attempts to reduce the aircraft’s pitch were largely ineffective. The aircraft reached a maximum pitch of 44º nose-up and the indicated airspeed reduced to 82 kt. The flight crew, however, were able to recover control of the aircraft and complete a subsequent approach and landing at Bournemouth without further incident. "

Crews need to be constantly alert and not become "passengers" by assuming their aircraft will perform flawlessly every time.
Well, with AP engaged the trim can do what it wants.
I never flew the B737, so I don't know how that one behaves, but I have a clear idea of what I would think ideal.
It would be ideal if the stick longitudinal position represented the total pitch moment. Fully back : everything is pulling fully up (THS and elevators), and vice versa.
So if your aircraft is slow, you feel it because your hand/arms are backwards. That is, if your airplane is an awkward position you will feel awkward too.
And the trim only purpose would be to set the zero force position.

If I recall correctly, light aircraft with an AP work like this, and you've never heard of a pilot who applied the right flying technique stall and crash in this type of aircraft (or if you did, it was because of other factors such as flying recklessly into conditions that they're not trained or equipped for). And they have much less yearly experience than airline pilots.
There is nothing 'dangerous back there' to a properly trained Airbus pilot. I think you have been very badly taught the Airbus and also your scan needs revising and improving. I think your problem is with your 'trainers' not with Airbus design.
I'm sorry but my airline uses the standard airbus TR. The trim wheel was never in the scan. The amount of manual flying in degraded situations is minimal, just read the latest syllabus to count how many minutes there are...
And if this type of unexpected THS behavior crashed at least 4 medium/large hulls (I'd have to look for others) then I don't see how you can deny that it's dangerous.
Did you imagine yourself for one second with the THS going unexpectly full up ?
Even if you noticed, did you imagine yourself pushing down the wheel ? How many turns would that be ? How much time would it take, with both hands ? What else could you be doing at the same time since you would have to look at the small numbers in the pedestal ?

[CVividasku]

For the sake of honesty, I just read again about the flydubai crash. It showed that there were also accidents where the pilot was in full awareness of the THS position.. So I guess there is no simple answer. Maybe mixing the advantages of both systems would help.
A system in which the airplane helps the pilot but in complete transparency.

[Vessbot]

Given how the crew spent 90-95% of the time with the stick aft of center requesting nose-up response, the argument over how “hidden” the airplane’s lack of nose-down authority was, seems to me kind of moot.

[Xray4277]

I know AF4447 has already been discussed almost endlessly elsewhere on here, but having just read Bill Palmer's book, the one thing which I had never really thought of before is this.- in less than the time it takes to read a chapter of the book, AF447 went from close on 7 miles high to crashing into the ocean. 4 minutes and 23 seconds from AP disconnect to oblivion.

Sobering to say the least and a poignant reminder that human weaknesses and human errors are so often pivotal in any disaster.