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THS 13 degrees nose-up

The BAA report says: "At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The Trimmable Horizontal Stabilizer (THS) went from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight."

Excuse my ignorance, but what is spposed to have this effect on the THS? Explicit setting by the pilot only, or is it somewhat under the control of FWB logic? Does Alternate Law change that?

Also: was that THS setting enough to make stall recovery near impossible?

Just a quick question from an interested bugsmasher pilot (no real experience of high altitude flight dynamics) :)

We know that pitch + power = performance.... and lots of talk here about how that could potentially been the answer here. However, if the aircraft has reached a stalled condition at altitude, is some action required to break the stall ie: nose down, power/idle etc. before going to the known power/pitch? If you have unreliable airspeed, how would you know that you're not stalled any longer and could engage the known power/pitch?

Just my own commentary - if Airbus want the aircraft to be fully protected by the computers, they need to make sure that it's very difficult to reach that non-protected state. It certainly seems that having three pitots of the same type and basic design with similar failure modes looks like a single failure mode that can lead to that non-protected FBW state.

JJFCC

Quote:

Why did the autopilot then auto-thrust disengaged ?

Probably (and it is sorta unclear from the wording of the report) the turbulence caused the AP to drop out.

If the AP can not hold the plane level it gives up and hands the plane to a (presumably more qualified) human. From the brief wording of the report, it sounds like that's why the AP dropped out... Then the PF did some rather odd things.

the difference between missing and confusing indications

From various posts I get the impression that the difference between missing indications and wrong indications is not always fully recognized.

Flying partial panel is easy if some instruments are just shielded off. It's a different story if they show conflicting information (e.g. a toppled horizon). It gets really difficult when not only airspeed shows impossible values, but other airpressure derived readings like altitude and climb/descent rate go to their stops (which they might do if static ports are clogged). Combine this with the sudden transition of a quiet lazy night flight into a nightmare of flashing alarms and horns, tripping autopilot, autothrottle, runaway trim system, law changes and a thick black night in IMC and the old man not available. The crew did not have the option of pressing the "pause" button and sort out quietly which readings make sense and which do not and consider what the hell had hit them. A stream of computer messages just added to the confusion.
It would probably have been much easier to fly this "no pitot" aircraft with a dark panel, using the standby horizon only and the throttles. But alas the displays must have shown a nightmare of utterly confusing and jumping readings, flashing symbols and a cacophony of warnings and alarms. Too much for the poor crew. Manageable maybe for some well trained and fully alert crew but certainly not manageable for most of the pilot bashers contributing to this forum.

Two's in,
I'd agree with your Cognitive Dissonance theory; that sudden, disorientating WTF!?
The only thing I can add is that I hope everyone has, over the past couple of years, covered recovery from unusual positions and thrust/attitude flying in their sim refreshers.
I feel lucky to have trained in the mil where cost was less of an imperative and we were given a little jet to throw around - useful confidence building for those, like moi, who are not exactly God's gift to aviation.

Entering the Deep Stall at High Altitude - ballistically

Quote:

Engine-eer said: "When the system is in alternate law the auto-trim function is disabled. Pushing the stick forward only results in limited elevator motion. Trim must be addressed by the pilot in this mode, so simply pushing the nose down isn’t going to retrim, the pilot has to do it manually.

This still doesn’t address why the trim was moved to the 13 degree nose up position."

I'm a little uncertain about this horizontal stabilizer position of 13 degs nose-up (from an initial 3 degrees prior to A/P and A/T disconnect). Is it a trim-wheel setting or does it refer to the horizontal stabilizer being 13 degrees up at the leading edge (i.e. a nose-down couple setting). If it's the latter then perhaps the pilot was fighting the post A/P disconnect out-of-trim involuntary pitch-up by manually winding in some nose-down trim..... as he sought to oppose that pitch-up.

However if the Shadow's version of events leading to the zoom climb are correct, when the aircraft topped out circa FL380, it was sporting high power and entered its stall quite ballistically, whilst out of trim. I've a hunch that a stall entered thusly at a very high altitude is itself a very different kettle of fish ...... to the common garden variety level flight approach to a stall (the classic 1kt/sec deceleration). Try throwing (i.e. propelling) a paper airplane off a cliff and then compare its trajectory with one dropped in a level flight attitude. I know that propulsion isn't in that equation but you get the idea, right? What I'm leading up to is that it's not a flight-tested regime for airliners and it may well be embedded and unrecoverable at 40 degs AoA. You might have to try configuration changes or engine asymmetry to become aerodynamic again.

I could liken it to a fall into an inverted attitude from a hammerhead tail-slide stall with fwd stick (one of my favourite low-level aero routines). You needed to throw out the ventral airbrake to get a good rate of re-pitch to the downward vertical for recovery (looks very different with/without that airbrake inject - you can tell from the smoke). Without the airbrake, on a video you can see that invtd stall attitude remaining constant for the descent. That was a theory behind Skippy O'Dwyer's death whilst doing that same stunt.

Some dynamic and ballistic entries to stalls/spins can have surprising results. Anybody who's flown inspin aileron on a JP-5A spin entry will know to what I refer.

The BEA's contribution on 27 May was just a data-dump. It's too early to conclude anything about how those AF447 pilots coped with that sudden pitot-initiated maelstrom. But it is becoming apparent that weather and storms had little to do with the scenario. You can pick up ice crystals during a protracted cruise in smooth CirroStratus. That there was some weather around was not unusual for the ITCZ.

Quote:

This is not correct. When the system is in alternate law the auto trim function is disabled. Pushing the stick forward only results in limited elevator motion. Trim must be addressed by the pilot in this mode, so simply pushing the nose down isn’t going to retrim, the pilot has to do it manually.

Yes, while in alternate law (and with the AA over 40º, abnormal attitude law) auto-trim is disabled. However my comment was in regard to the scenario Yipoyan referred to with the Chinese A300 Go-Around. In this instance, had a nose down input recovered the stall, and thus normal law returned, the auto-trim would have moved nose down.

@ Cleared to cross

Why mention the Standby AH? From the swathes of pages about this very distressing accident, I don't see any reference to the MAIN Attitude Indicator on the PFD(s) being U/S ...
ATTITUDE, surely, was the clue they missed - but why? The aircraft seems to have been in trim and flying normally, but perhaps with a bit of turbulence ... I won't go on, but this over-insistence on the Airspeed indications makes me feel that contributors to this (and "the other") forum are making a similar error.

As a long-retired military pilot, I once flew what were then known as "medium range twin-jets" for some years in the ITCZ and had the odd encounter at night with an unsuspected cumulo-bumbulo, so I feel a great deal of sympathy for the two pilots at the controls of 447 that night. My point is really that the thread(s) aren't dealing with the main issue. Aeroplanes aren't like cars, with "just" a speedometer on the dashboard, and you "drive" them differently.

AIRBUS COMPUTER-SMARTER theory...

I will begin with the A310-325 approaching CDG years ago.
Capturing G/P from above the plane overspeeded the flaps placard, obviously, THE SMART COMPUTER decided it is a go-around so throttles up, and nose-up trim!
The dummy in the L/H site pressed the yoke, and pressed the yoke and...
---> THE SMART COMPUTER trimmed further nose up, and trimmed...
So the little thing goes strait up like the smoke, one engine flamed out, the other was near enough and... at speed ZERO...
Yes, you got it, tail-way back to the Mother Earth...
It's said somebody gave a rudder input, like in an ''acrobatic pendulum'', the plane turned sideways the engines regained power by themselves...
The ground looked terrifically close and the front guys... Were, maybe wetting their underwear.
All that from 4000ft. to... God Almighty and back to 1800ft. when, in control, the bird lingered to the RWY.

I know nothing about A330, was only in the rear, from MRS-ORY many times in the '94, '95. Impressed by the wing mechanization, I know guys who said to me that A330 has 5 ways for each computer, for each thing aboard and it's the best of her class!
But the side-stick, and the computer all-knowingly...
Well I hardly understand how close they are to a play-station... and there are some presumed innocent living people in the rear, aren't they!?!

YES!!! the ''AVIGATE-NAVIGATE-COMMUNICATE'' ignored-rule is likely what took them out of sky ''God Bless Them All'',
But they had only 200 seconds from sky-high to death and so many announcements, faults, and an adverse responding computer in rough turbulent weather!!!
And they were JUST HUMANS trying in pitch black night, in rocking clouds to deal with all that havoc???
Just remember, if you know, the Qantas A380 incident!?!
Five mega pilots, hyper-instructors, ultra-experienced guys dealt 2h30min... 150min with announcements, check-lists, and defective gauges, systems and WHAT???!!!???
Finally decided to leave it all aside, go to land and to see on ground what's next...
They smartly decided to wait 90min on RWY, with the engine running, PAX ON-BOARD... a.s.o.!?!
AN THEY HAD ONLY ONE ENGINE EXPLODED!!! I don't say it was easy, NO! Just trying to compare the two situations?!?
In AF447 they were only two F/O, with probably the P/F NOT IN HIS LICENSED PLACE...!!!???!!!

What said the BEA

The BEA gave few informations in this may 27 report but one message :

„ the airplane climbed to 38,000 ft,
„ the stall warning was triggered and the airplane stalled,
„ the inputs made by the PF were mainly nose-up,
„ the descent lasted 3 min 30, during which the airplane remained stalled. The angle of attack increased and remained above 35 degrees,
„ the engines were operating and always responded to crew commands.

Everyone understand that the PF didn't cope with a stall warning.

This is the only thing that said the BEA. Everything else is speculation.

I myself have hit sever icing at FL 320 and it comes apparent as the noise in the flight deck rockets and the windshield, even at night, whitens very quickly. Thankfully for myself it lasted all of 20 seconds.

-Time and time again I can't understand why crews execute the wrong stall recovery technic as seen again in this case. Stall recovery has never been taught different from day one. Pitch down, roll wings level then power!

:confused: Why fight to maintain level if the aircraft is going down? (Referring to nose up inputs, but maybe the pilot was trying to avoid a believed overspeed. Once a pitot is blocked and an aircraft climbs, speed will increase. This might explain why he initially pitched up thinking he was caught in a sever up draft.)
:confused: Why apply TOGA thrust to recover from stall when you have altitude? The thrust coupling would have been a great hindrance to attempts to drop the nose.
:confused: The aircraft is stalled in Alternate Law, it is obvious they had icing, why did the PF use aerolons to recover the wing drop? Inducing a cross control stalls. Correct method, as always been taught, use rudder to recover a wing drop.

-I am sure engine anti-ice would have been on, but did anyone select Wing Anti-ice? Further note, tailplane was probably heavily iced as well not helping stall recovery.

HKPAX You're obviously not a A330 pilot or never hand flown your aircraft high altitude and don't know much about about the plane you "fly". EVEN in alternate law the pitch is a G request, so softly pushing on the stick at high altitude will give the same effect as sofly pushing on the stick at sea level. I know this to be true, as I have had to fly in Alternate law at FL340 because of a dual FMGC failure. If we were talking Boeing, you'd be right. But we are not! Second, a change from level flight to a 7'000ft/min climb then a 10'000ft/min descent in such a short time is definitely gonna be noticed by all as high Gs are involved.

Engine-eer I assume you are an engineer, so I don't expect you know about the auto trim operation on an Airbus, like you wouldn't expect me to know how to change an engine on one.
The auto trim function only ceases when:
-Alpha Floor is engaged (Not available in Alternate or Direct law)
-Below 50ft RA
-Load factor drops below 0.5g
-Aircraft in high speed protection (Not so as aircraft was stalled)
-Pilot manually over rides via trim wheel

Note: In alternate mode. Pitch is load factor and roll is direct.

Nojwod wrote," As expected reading the last few pages, the usual crowd of perfect pilots comes on to disparage those pilots who were imperfect, the only difference between the perfect pilots and the rest are that the perfect pilots strut around here like a bunch of cockerels, the imperfect pilots are out there facing the real world scenarios...

Anyway that aside, to me what was said and the actions of the PF, with no real dissent from either of the other two imperfect pilots who were there, indicate that something either in the instrumentation or the plane's response to inputs was diametrically opposed to what the crew expected to see or experience. Unless you perfect pilots believe that all three highly trained pilots on the flight deck on that dark night were so grossly incompetent that they could not follow basic airmanship as a matter of course, then there must be some factor(s) that the data recorders have not been able to provide and which may never be known.

As for the dogmatic statements by some perfect pilots above that the crew shouldn't have flown into the storm or flew a perfectly serviceable aircraft into the sea, your comments are beneath contempt, not only for their insensitivity but also for their gross simplification of a situation that you in reality know absolutely nothing about. "

I beg to differ in approach:
a. You should expand your horizons by going through the NTSB database of fatal accidents, to find out what mistakes pilots make.
b. That should lead you and everyone taking control of an aircraft to the understanding that if you are not a perfect pilot, quickly get away and never come back. I have seen enough in 36 years of flying, you can trust what I say.

Quote:

Sorry I thought you were referring to this case.

What does it take to have the FC system return to normal law? Does the system do that automatically after it has decided that the AS sensors were previously declared as faulted, or does it have to be reset manually? Is there any indication that the system returned to normal law or that the autotrim system moved the trim from 3 to 13 degrees?

Really do feel for the pilots on this A330, they called the situation wrong and paid the ultimate price.

Question is how does an A330 or to that matter any airbus behave in a 'deep' stall. Do standard stall recovery techniques still work ? Actually has anyone experienced a deep Stall condition in a FBW airbus ?

side stick and unusual attitudes

Sorry to say but lot of crap on these threads.
Let's wait more details.

-What do u think about sidestick philosophy in unusual attitude ?

Now, the PNF is really missing important feedback : what is the colleague doing on his stick ???
Normal flight, you have feedbacks on PFD : attitude etc... but here : with attitude of 40° up, stalled, you don't have a clue of what HE IS DOING !
You can assume he is pushing down BUT YOU DON'T KNOW ! Instruments won't tell you !

Now, the table was certainly out at CRZ, so you see NOTHING of the colleague stick...

I like AB but I would prefer 2 CONNECTED STICKS with VISUAL FEEDBACK on this scenario and if i see that the other one is keeping it fully AFT for too long, I WOULD CERTAINLY NOT LET HIM DO.

Now to think that a normal pilot pulls full aft stick sooooo loooong.... hard to believe...

What u think ??

If my memory serves me correctly, even the dear old VC10 had AoA sensors.

Also there was a Northwest Orient 727 crew who crashed because they forgot to switch on the pitot - static heat before take off.

On the climb out their indicated airspeed was increasing and in response they simply increased pitch to correct the "overspeed", until the jet went into an unrecoverable super stall.

Most swept wing aircraft in a deep stall will pitch up and increase the AoA. Perhaps a stick pusher is required? No VC10 was ever lost to a super stall.

Touch'n'oops

Sorry, I confused Alternate Law with Direct Law. In direct law autotrim is disabled. That is what occurred in the Air New Zeland crash, where the trim was left at the last autotrim position (near stall) and the aircraft then pitched up as airspeed increased and stalled which they did not recover from.

If the aircraft was in alternate law then the autotrim was enabled. If that is the case, then can we assume that the change in trim from 3 degrees nose up to 13 degrees nose up was commanded by the auto trim system? If you push nose down, how long does it take for the autotrim to respond? As somebody asked earlier, could this high pitch trim setting made the aircraft unrecoverable?

REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb

2 - ANALYSIS

2.1 ATC Actions
The aircraft left its cruise level late, on instruction from the ATC. The IAF, the MEL VOR, was flown over at an indicated speed greater than 300 kt whereas speed is limited to 250 kt below level 100. ATC asked the flight crew, who announced a vertical speed of 4,000 feet per minute, to accelerate its descent to level 60, which, according to standard procedure, should be reached 7 NM after passing MEL.
Heading 330 given by approach control tended to bring the aircraft practically to the FAF for immediate interception of the ILS. Heading 310 reduced the closing angle for the aircraft's route in relation to the ILS axis. This angle was still too wide for the aircraft to align comfortably on the ILS and follow it immediately, all the more in that the indicated speed was still about 235 kt on interception.
This type of procedure is a practice that allows for traffic to be accelerated when meteorological conditions are favorable, which was the case. The flight crew could, however, in compliance with regulations, express its disagreement if they considered headings given would lead the aircraft to intercept the ILS too close to the final descent point. They did not do so.
There was no radio communication exchanged during the incident itself.
After the aircraft came out of the stall, the controller suggested to the flight crew that they stay on heading 180. This complies with the operational instruction aimed at keeping any aircraft with reduced maneuverability to the south of Orly. They were then left the choice of heading to return to their final approach as they wished.
New clearance for landing was given at 10 h 49 m 54 s. Note that no superfluous requests as to the cause of the incident were made by the controller.
2.2 Incident Sequence
The CVR transcription does not indicate an approach briefing. The Captain was performing an automatic approach.
In level flight at 3,000 feet, the aircraft crossed the glide slope before intercepting the localizer. The flight crew seems to have attributed non-capture of glide to automatic pilot system malfunction, whereas the system logic subordinates it to that of the localizer, and disconnected the automatic pilot. The systems configuration then became AP OFF and ATHR ON. The aural warnings announcing disconnection of the AP and downgrading from CAT 3 to CAT 1 of the system landing capability were not commented on by the flight crew.
The aircraft was now in being flown manually and locked onto the localizer at an angle of 52° at 210 kt. It was high in relation to the glide slope and to the north of the localizer axis. Aligned and set to descend, the speed was too high and the indicator for deviation in relation to the descent glide slope showed one point. The vertical speed was not commented on.
At about 2,750 feet, when the “altitude alert” signal sounded, the co-pilot selected 4,000 feet as the altitude to reach in the event of aborted approach, in order to cut off the warning signal.
This selection, before the capture of runway alignment, was premature and its value was greater than the level-off altitude following a go around.
Although the throttle levers had been in “flight idle” position, the speed remained high, the aircraft being two hundred feet above the glide slope. The Captain decided to put it in landing configuration. On each of the successive extensions of slats, flaps and landing gear, the speed was close to the maximum authorized value.
The flaps were positioned at 20 degrees as soon as the speed of 195 kt, that is VFE, was reached. A temporary and minimal excess of VFE (two knots for two seconds), perhaps on going through turbulence, was recorded. The speed protection logic then triggered mode reversion, thus initiating CLB mode due to the altitude selected being higher than the aircraft's altitude.
This change was not noted by the flight crew who were apparently not reading the FMA and did not notice the LVL CHG pushbutton illuminated on the FCU. They did not comment on the “triple click” signal.
While the throttle levers were advancing at their nominal speed on automatic by one degree per second, an action, which seems to have been unintentional and unconscious by one of the pilots, on the elevator trim control button led to deflection of the THS, at constant angular velocity, over ten seconds, up to the maximum value of thirteen degrees nose up. Although the characteristic "whooler" aural alarm was heard continuously for ten seconds, it was not commented on by the flight crew and led to no reaction from them.
This was probably the Captain's responsibility, who was at the controls. It may be explained :
either by incorrect positioning of the left hand on the control column which would have caused the thumb to press the trim control button,
or following confusion between two buttons, that of the trim control and that of the instinctive AP disconnect. This pilot has considerable experience on the BAC 111, an aircraft on which the pushbutton on the left control column horn is the automatic pilot instinctive disconnection control. We may surmise that when he sought to counter the aircraft's tendency to pitch up without understanding its origin, confusion could have set in and having reverted to old reflexes in seeking to disconnect the automatic pilot (already disconnected) he operated the control located in the same place as the AP disconnection on BAC 111.
The co-pilot's phrase “take over manually” is not sufficiently explicit. As the aircraft was no longer on automatic pilot, it would have been more appropriate to say “disconnect the auto-throttle”. This may also mean that the co-pilot believed that one automatic pilot had remained active.
In any event, deflection of the THS created a strong nose up force to the aircraft that the pilot countered by energetic efforts on the elevators, which put the aircraft in a totally out of trim situation.
This out of trim situation was the second crucial feature in the sequence of events in the incident, the first having been the AFS mode reversion.
It seems that the flight crew was unaware of this total out of trim situation. They did not carry out the instructions provided for in the event of “High Pitch Force” or “Abnormal pitch behavior” that provide a response to this situation.
As the auto-throttle was still in operation, the pilot overrode it by manually moving the throttle levers to flight idle for ten seconds before suddenly pushing them back to the maximum thrust position. Four seconds later, he moved them rapidly to flight idle for two seconds, before again pushing them to maximum thrust.
To try and explain the first positioning of the throttle levers to maximum thrust, we can propose two hypotheses :
the Captain, noticing the strong reduction in the VC trend, may have thought that the speed was going to decrease significantly. He may have advanced the throttle to avoid stalling,
the Captain, noticing the problem in the pitch attitude, which would prevent him from continuing his landing, seems to have decided to climb so as to obtain more favorable conditions to deal with the problem. No reason was found for the two other movements of the throttle levers and interviews with the flight crew did not contribute to an understanding of this. It is also clear that the crew, after such a stressful event, could neither remember all their actions, often probably of an instinctive nature, nor even less explain them.
Under the aerodynamic effect of THS deflection and under the mechanical effect of thrust, the aircraft was thus subjected to a nose up force that could not be controlled by elevators. It rapidly assumed an extreme pitch attitude and angle of attack.
The level of force applied on the elevators with just the left hand, while the right hand was maneuvering the engine throttle levers, induced load on the aileron controls. The aircraft then went into a regular and slow roll.
The flight crew was thus confronted by four problems, with the need to:
Hold the aircraft on a descending path
Counter the nose up tendency and control thrust
Pilot the aircraft by switching to instrument flight
Analyze and decide. The Captain reached a point of saturation and so announced a MAYDAY situation, meaning he indicated that he was in a critical situation. It should be noted here that the flight crew neither acted in a coordinated manner nor relied on rules for dealing with an emergency situation. The Captain did not delegate any task or action to the co-pilot who, in turn, proposed no emergency action. Any notion of managing the flight crew seems to have been forgotten.
The FD indications on the pitch attitude to be followed to reach an altitude of 4,000 feet could only be interpreted with great difficulty by the flight crew. Also, due to high pitch attitudes, the PFD was automatically purged, to leave essential information only.
The aircraft thus reached an altitude of 4,100 feet on the verge of a stall, with a minimum recorded speed of about 35 kt. The protection system against high angles of attack cut in and reduced THS deflection from –12.7 to –8.8 degrees, and as a result, the angle of attack from 42 to 30 degrees. The PF does not seem to have noticed the THS pitch down movement, particularly given that a movement of the THS commanded by the automated systems is not announced by the “whooler”. This triggered a reduction in pitch attitude. The aircraft did, however, stall; the “Cricket” stall warning signal and stick shaker were only activated later during descent (see paragraph 2.3.2 below).
Immediately before, during and after the stall, due the unreliability of the total pressure, the ADC no longer provided speed data, resulting in automatic disconnection of the ATHR, with the throttle levers remaining in the maximum thrust position.
Just before the stall, the Captain pulled the control column fully back, bringing the elevator to 23 degrees nose up. He then pushed it fully forward, while continuing to counter the roll of 75 degrees to the right with the ailerons. The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable.
During the descent, the pilot, helped by the automatic setting of the THS to –8.8 degrees, reduced angle of attack, gained speed by reducing drag, performed a gentle pull-out (load factor of 2 g for five seconds) and adjusted power. The aircraft came out of the stall at a height of eight hundred feet, still out of trim. The flight parameters were apparently stable thanks to thrust modulation.
Alpha-trim protection was automatically cancelled as soon as the aircraft came out of the stall : the THS returned to its previous deflection of –12.7 degrees. This automatic movement, without a “whooler”, seems to have gone unnoticed by the Captain. The Captain flew the aircraft, still totally out of trim, on a slightly rising trajectory, and set thrust to around 60% of N1. The speed decreased regularly and reached 140 kt. This situation carried a high potential risk : in the event of an increase in thrust for any reason, the aircraft would inevitably have started climbing with a high angle of attack.
The co-pilot, reading the ECAM, announced “Pitch trim off”. In fact, the drifting caused by the rolls had disturbed angle of attack assessment and led to their automatic disconnection. The co-pilot re-engaged them and performed tests by deflection in both directions. The “whooler” was identified and the co-pilot declared the trim setting system to be operational. He reduced deflection to –8.4 degrees. This action to reduce the THS angle was beneficial. It nevertheless remains an example of simultaneous piloting, performed without the knowledge of the pilot flying.
On an outward leg on heading 120, the aircraft at 195 kt and at 2,000 feet was now only slightly out of trim (THS –8.4 degrees nose up; pitch 8° nose down).
The Captain at first refused to use THS trim. About eighty seconds later, inputs recorded on the FDR and selector noises on the CVR show that he used it but without announcing it, by short touches identical to his way of using trim before the event was triggered. Five minutes after total deflection of the THS, the aircraft was correctly trimmed and piloting had returned to normal.
Landing took place in configuration with slats and flaps 20 , which in the final approach, led to the announcement “too low flaps” from the GPWS. LOC interception took place by visual alignment with the runway axis. The aircraft crossed the glide slope, remained above then, finally, went below it. These deviations were not announced. The “glide slope” aural warning was heard on final approach.
On final approach, on reducing speed, the AFS triggered a mode reversion from VS to SPD. As the auto-throttle was disconnected and the flight crew was getting ready to land, this new mode reversion went unnoticed.
To summarize, this second approach was neither prepared nor stabilized.
Note : the CVR shows no attempt to determine the anomaly felt on the longitudinal attitude control system, THS and pitch. More generally, there would not seem to have been actions which could be called “return to basics” on the part of the flight crew. In the present case, this would have involved:
setting the aircraft trim, if necessary using the mechanical control wheel,
returning to standard flight situation, normal visual flight circuit, briefing and check .list,
possibly reactivating certain elements of the AFS, after consulting the ECAM. As soon as the situation seemed to have stabilized, conversations resumed in the cockpit. Neither the auto-throttle, nor THS deflection, nor the variations in thrust were mentioned. Neither was mode reversion from VS to LVL CHG brought up. The conversation mainly concerned the AP. The flight crew did not carry out a briefing for the new approach.
2.3 Operation of AFS Protection
2.3.1 Protection of Speed Envelope
The aircraft speed exceeded VFE before capture of ILS. Note that in these circumstances, protection against an overspeed is ensured according to the two following thresholds:
when the speed becomes equal to VFE, by switching to LVL CHG mode.
when the speed reaches VFE + 4 kt, by sounding a Continuous Repetitive Chime. The choice of LVL CHG as protection against excess speed led, in the circumstances of the incident, to an increase in thrust at a moment where the goal was to reduce speed, this being incompatible with the goal sought.
We may note that, if the automatic pilot had been active, it would have caused a nose up attitude, which would also have surprised a flight crew in the middle of intercepting a localizer and whose first objective was to reach the runway.
2.3.2 Analysis of the Stall Protection Logic
Stall protection is organized around three angle of attack thresholds, that for Alpha-floor, that for Alpha-trim and that for triggering the stall warning (see 1.16.1.4).
Alpha-floor protection could not play its role as, when angle of attack of 14.5° was reached, the throttle levers were already on maximum thrust.
Alpha-trim protection was triggered at a value for angle of attack of slightly less than 15° in conditions where the flight dynamics were close to the extreme. It should be noted that it also functioned after coming out of the stall by giving the opposite order to the THS.
The stall warning did not sound and the stick shaker did not operate in the flight phase prior to the stall. When questioned, the aircraft manufacturer indicated that the cause for non-operation of these two warnings was the disturbance of the angle of attack sensors due to the dynamics of the aircraft's movements, with the speed having dropped below 60 kt before the angle of attack reached 17.5°. The flight crew had, however, been warned of the approach of a stall by buffeting.
3 - CONCLUSIONS

3.1 Findings
The flight crew was properly licensed to conduct the flight. A third pilot undergoing familiarization was in the observer's seat.
The meteorological conditions were excellent.
The aircraft was normally certified and maintained. No non-availability of equipment (with the exception of the FDR) was noted. Ground checks after the incident, and subsequent flights of the aircraft showed no evidence of any operating anomaly.
The Captain, at the controls, started an automatic approach.
Approach control asked the aircraft to shorten its path, which led to ILS interception closer to the runway than provided for by standard procedure.
According to the systems logic, the glide, encountered before the localizer, was not automatically captured . The Captain then disconnected both automatic pilots, leaving the auto-throttle in operation.
An altitude of 4,000 feet was selected before establishment of the aircraft on ILS as go around altitude. The go around altitude in the procedures is 2,000 feet.
When flaps were selected at 20 degrees, the speed was slightly greater than VMAX, which activated speed protection, leading to reversion of VS mode to LVL CHG mode.
Due to the altitude selected being greater than that of the aircraft, the auto-throttle commanded an increase in thrust. The pilot maintained the aircraft on descent.
He accidentally caused the trim to its electrical stop at thirteen degrees nose up, which put the aircraft in a totally out of trim situation.
To counter the effect of THS deflection, he moved the elevator control to its mechanical stop of fifteen degrees nose down, by effort applied on the control column.
A sudden increase in thrust was commanded manually.
Under the effect of the additional force, the aircraft pulled up rapidly. The pilot continued to counter by continuous effort on pitch and by temporarily holding the thrust levers in the idle position. He neither corrected trim, which remained on pull-up stop nor disconnected the auto-throttle.
The aircraft took a path with a very steep slope, with roll angle reaching extremely high values. It climbed to an altitude of 4,100 feet and minimum speed recorded was 35 kt. Alpha-trim protection reduced the THS deflection by four degrees.
Under the effect of strong drift on full and rapid rolls, the angle of attack sensors were disturbed, which led to automatic disconnection of the two pitch-trims. The auto-throttle was inhibited for the same reasons.
Due to the dynamic of the aircraft's movements, the stall warning and the stick shaker did not function in a preventive manner.
The flight crew regained control of the aircraft after the stall. 3.2 Probable Causes
The direct causes of the unusual attitudes and the stall to which the aircraft was subjected were a movement of the THS towards the full pitch-up position and a rapid increase in thrust, both of which maneuvers were the due to the Captain, following an AFS mode reversion which was not understood. The pitch-up force caused a sudden change in attitude that the flight crew was unable to contain with the elevators.
The following elements contributed to the incident:
Too rapid an approach, due to a late start in the descent, followed by a reduction of the standard procedure.
Inadequate crew resource management.
Premature selection of the go around altitude and precipitous setting of the configuration with slats and flaps at 20-20, which led to activation of the speed protection.
Difficulty in understanding the action of the auto-throttle increasing thrust in its overspeed protection function. 4 - RECOMMENDATIONS

4.1 Measures Taken
After the incident and on the basis of the first facts established as communicated by the BEA([3]), the French Civil Aviation Authority (Direction Générale de l'Aviation Civile) informed French operators of the Airbus A 310 and A 300-600 (these two types have identical protection). It asked them in particular first to draw the attention of flight crews to the need to respect limit speeds provided for different aircraft configurations and, secondly, to ensure they are fully informed as to the logic of the protection system in the event of abnormal speed.
The DGAC also warned the civil aviation authorities of the countries using these aircraft, recommending them to take similar action with the operators under their authority.
4.2 Intermediate Recommendation
Following several accident investigations in which the Bureau Enquêtes-Accidents participated, the following recommendation was issued on 24 January 1995:
Various incidents or accidents (see list below) involving public transport aircraft show the following common characteristics:
1. Configuration: Automatic Pilot and/or auto-throttle lever (or auto thrust) in operation.
2. Circumstances: pilot flying overrides (voluntarily or involuntarily) the Automatic Flight System, or acts contrary to the indications of the Flight Director.
3. Aggravating circumstances:
  a) the pilot flying is not always aware of his action in opposition with the Automatic Flight Systems and never perceives the consequences thereof,
  b) the pilot not flying (even instructors) is not aware of the conflict between the pilot at the controls and the Automatic Flight Systems.
4. Consequences:
  - the reaction of the Automatic Flight Systems leads to potentially dangerous configurations: out of trim, engine thrust incompatible with the trajectory chosen by the pilot, etc.
  - Flight crew, either is not aware of the situation, and thus cannot take corrective measures,
    or observes the aircraft configuration without understanding the causes. This incomprehension (also related to limited knowledge of systems) leads to a loss of time in analyzing the situation, or even to an erroneous analysis, generally associated with a lack of adequate communication between crew members
    This has led to highly dangerous attitudes: extreme attitudes or rolls, loss of speed (including stalls) or excess speed, etc.
As a result, the Bureau Enquêtes-Accidents recommends:
- that a study be launched so that the pilot's priority over all Automatic Flight Systems is maintained in all circumstances.
This could be done :
a) by the disconnection of Automatic Flight Systems (automatic pilot and auto .throttle lever or auto thrust) in the event of conflict between the pilot's actions and those of the Automatic Flight System or Flight Director.
b) and/or by clear information in the cockpit (possibly an alarm) warning the flight crew of such a conflict.
List of events:
- Incident to an A 300 .B4 on approach to Helsinki (Finland) on 9 January 1989
- Accident to the A320 .231 VT .EPN at Bangalore (India) on 14 February 1990
- Incident to the A310 D .ADAC on approach to Moscow on 11 February 1991
- Accident to the B747 .400 F .GITA at Tahiti .Faaa on 13 September 1993
- Accident to the A310 .300 F .OGQS near Novokuzniesk (Siberia) on 22 mars 1994
- Accident to the A300 .600 B1816 at Nagoya on 26 April 1994
- Incident to an A310 .325 on approach to runway 26 at Orly on 24 September 1994
4.3 New Recommendations
4.3.1 Speed Protection System Activation Display
The flight crew noticed neither the initiation of the flight envelope speed protection nor the mode change which resulted from it. Further, we may note that the denomination "LVL CHG" is inappropriate to indicate activation of speed protection. LVL CHG is the process used and not the goal.
The BEA considers that recommendation 4.4.2 issued in the context of the investigation into the accident that occurred on 20 January 1992 near Mont Ste Odile corresponds to the problem identified here. It is repeated below, with the grounds given:
In its analysis of this accident, the commission has been led to note deficiencies in the effectiveness of the display to the flight crew of the various active modes, the references used, actions in progress and targets pursued with regard to the Autopilot devices, notably in the vertical plane. Most particularly, in the opinion of the commission, the total information presented is inadequate in terms of its likelihood of alerting a crew, who at a given moment have an incorrect mental picture of the state of the automatic devices. In practice, a good number of observations made by the commission apply to one degree or another to all new-generation aircraft …
Consequently, the commission recommends that for all new-generation aircraft:
- consideration should be given by the competent authorities and organizations with a view to improving, in a standardized fashion on an international basis, the presentation and the symbols for displays and information relating to the different Autopilot active modes, notably in the vertical plane.

JJFFC - Do you agree to this test ?
In a test, any pilot who ears a stall alarm who hadn't nose down within a quarter of a second should be fired.

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Disagree.

1. maintain aircraft control
2. analyze the situation
3. take appropriate action

A reaction to a stall warning, absent other confirming indications, is inappropriate. Maintiain aircraft control(#1) sometimes means 'do nothing immediately or drastic', verify a/c performance state(#2) and then proceed to ignore waring(if false) or reduce AOA if warning/stall is confirmed (#3).

Agree with you entirely when you mention cognitive dissonance - it's involved somewhere.

From what I've heard :ok: until you've been involved in an aircraft coming "unglued" you have no idea how quickly your comfy world can turn to a crock of S**** and subsequently just how difficult it can be to metaphorically "step back" and analyse the situation objectively.......

We may well eventually discover what information the AF crew had available to them - we'll sadly never know what they perceived.

You are fired

As 80% of the pilot considering what is said in the report above :
" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable."

Don't think. Nose down.

Some points:

> Let's not use the term "deep stall" in reference to this accident. A "deep stall" is a specific kind of stall where the attitude of the aircraft is such that the wings block airflow to the horizontal stabilizer, making elevator inputs useless for recovery. Almost always involves a "T"-tail design, which does NOT include any Airbus aircraft. (oopps - edited to include NOT)

This was a pronounced, possibly extreme, and prolonged stall (it appears), but NOT at any time a "deep stall."

> I find huge fault with an audible stall warning system that cuts out as the AoA gets worse, and then cuts back in again during recovery. Yes, a good pilot should be able to recognize a stall by other means than the audible alert - but an alert that a) stops while the situation is still getting worse and b) begins screaming again when the pilot does the RIGHT thing (lowers AoA for recovery) is just ludicrous.

A/P Not as Smart as Touted

The A/P should have rejected the errant airspeeds, gone into pitch and power hold mode, and stayed in normal law.

Quote:

Correct method, as always been taught, use rudder to recover a wing drop.

Really?

Does anyone else disagree with the above post?

I recall the UK CAA sending out a memo around about the use of rudder in stalls...

Right back to the basics ...
Rudder should be used to maintain balance only...

Perhaps they reacted to winshear, rather than stall.

Full back stick and TOGA, then hold both until the aircraft flies out of the problem.

Not enough thrust at high level, protections not there so the computer cannot stop the pilot holding the aircraft in a stall.

Mind set on the wrong cause of sudden loss of airspeed.

The dreadful fact seems to be that they had a flyable aircraft that they failed to fly.

With respect to the "we have no valid indications" comment, is it possible that the crew were just so convinced that they were in a nose-down dive (idle throttle, pulling back on stick) that they simply concluded that any instrument which contradicted this belief (such as attitude indicator pointing up) must be wrong?

The way I read the report it continously stated that the plane was in a nose up attitude. And the airspeed very slow. And it seems to me that they had no control over the stabilizer/elevator.

Birgen Air flt 301

Just for the record the Captain discovered his airspeed was out in the beginning of the TO roll before V1 but elected to go anyway. It's on the CVR.

The taped static port occurred on the Peruvian 757. Unsure if they were aware of it during take-off.

I can't help feeling there is a bit of the Eastern 401 problem here. If they were dealing with all sorts of other warnings, was anyone looking at attitude, altimeter, R.O.D.? An additional factor; could the PF be inadvertently holding full nose-up control? Unlikely on a conventional aircraft, but could he have been so busy with the other problems that he didn't realise he was doing it? The call at ten thousand is unusual; surely someone would have reacted to that, unless it was a Pavlovian call in the confusion. I don't think we will be able to know much else until the full CVR is made available.

The maddening part of Birgenair is the Capt merely had to reach forward to his outboard instrument panel and rotate his Air DATA switch from NORM to ALT.

AeroPeru 603 was a through flight from KMIA to Chile. The arriving 727 was grounded for maintenance upon arrival Lima, so they hurriedly pressed the 757 into service. I don't know if it was a dedicated 757 crew, or a crew who normally flew both and was expecting to continue with the 727.

This accident is pretty well covered on wiki. I don't know how many line pilots would have been successful in the same circumstances, but the problem was surely more challenging than AF447.

New stall recovery procedure

This is interesting, sorry if posted already:

Revised stall procedures centre on angle-of-attack not power

Very relevant indeed.

Quote:

Let's not use the term "deep stall" in reference to this accident. A "deep stall" is a specific kind of stall where the attitude of the aircraft is such that the wings block airflow to the horizontal stabilizer, making elevator inputs useless for recovery. Almost always involves a "T"-tail design, which does include any Airbus aircraft.

Agreed. "Deep Stall" has developed a second usage in the media, where it seems to mean a rapid breaking stall from a high pitch attitude. I've even caught myself using it that way from time to time. :(

I noticed a mistake in my original that you quote - a critical missing "NOT"!

The real key to this accident will be to figure out why the PF thought holding full back stick all the way down was the correct response. I don't jump to a conclusion that it was simply "error." I'd like to see as good a re-creation as possible, from the data, of what the cockpit environment was actually telling the crew (alarms, instruments, ECAM messages, seat-of-the-pants, etc.).

Two of the clues that normally identify a stall would have been missing (airspeed) or perhaps disguised (buffet in the middle of convective turbulence - the pilots clearly were expecting buffets from turbulence, having changed course and warned the cabin). Pitch on the AH is not a trustworthy indicator of AoA (one can be 20° nose-down and still stalled with a 35° AoA).

I can't conceive of holding full back stick for 4 minutes in any aircraft. But I also can't conceive of any other trained pilot doing it unless some outside influence was suggesting such a bad idea was really a "good" idea. So "why"?

In a test : Any pilot that doesn't nose down earing a stall warning should be fired

@ Flight Safety:ok:

Thank you for your 20:24

Your link :

"A formal document detailing the rationale for the revision points out: "There have been numerous situations where flight crews did not prioritise [nose-down pitch control] and instead prioritised power and maintaining altitude."
Operational experience has shown that fixating on altitude, rather than the crucial angle of attack, can result in an aircraft stalling."

Try the test : a pilot that doesn't nose down immediately when earing a stall warning has not understood what is a stall : the plane is no longer a plane, it is a cucumber.

If you don't nose down, you are dead within a minute or two.

The trouble is that :

" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable."
REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb

Quote:

Originally Posted by thcrozier (Post 6479576)

"Deep Stall" has developed a second usage in the media.

The same has unfortunately happened with "FBW".

"Fly-By-Wire", as such, simply denotes using "electrical signalling" (the old-fashioned British term), i.e., using an electrical connection between the pilot's controls and the hydraulic servo-control units that move the flying control surfaces, instead of cables and rods.

Since.... it has become a synonym for hooking up all kind of digital electronic systems between the pilot's controls and the flying control surfaces, leading to the "now why is it doing that !!??" syndrome, and the mistrust, expressed here time and time again, of digital systems and software in general.

The real issue with "FBW" here seems to be with the digital part of the system... in which case reference to the "DAFS" (Digital Air Flight System) would be more appropriate... but I agree, the term "FBW" has now unfortunately become part of the vocabulary.

Concorde used FBW, in the real sense, but all of the rest of the AFCS (AP, A/S, A/THR, A/TRIM, SFC, etc.) was purely analog.
And FBW worked fine all the time... there was a mechanical back-up, which basically was never called on in service.

Stall Recovery Parachute

I understand if that a stall is not dealt with properly immediately - or incorrectly - it may develop into a unrecoverable stall.

At what stall-angle (angle of atack) will the elevator be virtually useless to lower the nose? 30 og 40degrees?

Will it be possible to recover from 40 AoA stall using alternative methods? (asuming the elevator is not able to get the nose down) Indtroduce rotation /spin /wing-drop using rudder or ailron or single-side engine power.

Also - At high altitude - why would anyone use engine force to recover from a complete stall - concerning the potential disastrous delay it introduces to lowering the nose and AoA.

And would it be a idea to introduce an obligatory "stall recovery parachute" - it would perhaps be the only option to safely get a severely stalled aircraft into back in business.

Are even large passenger planes tested for a severe stall in real life?

High Altitude Operations

It might be useful for some to look at this:

http://www.faa.gov/other_visit/aviat...Operations.ppt

The notes for slide 29 are very interesting.

@Flight Safety:ok:
p29:

An airplane wing can be stalled Any airspeed, any altitude, any attitude
Pilot Tip:
If the angle of attack is greater than the stall angle, the surface will stall. Attitude has no relationship to the aerodynamic stall. Even if the airplane is in a descent with what appears like ample airspeed - the surface can be stalled.
Understand the difference between:
“Approach” to stall recovery
Stall recovery
Dramatic difference in recovery technique
Know the Difference

p43
http://www.faa.gov/other_visit/aviat...Operations.ppt
High altitude - stalls

Low speed buffet mistaken for high speed buffet
Actual full “Stall Recovery”
Higher altitudes:

Available thrust is insufficient
Reduce the angle of attack
Trade altitude for airspeed.

Could all the pilots on Earth, read that.

Quote:

Yes, while in alternate law (and with the AA over 40º, abnormal attitude law) auto-trim is disabled.

Then is this site in error, because it states auto trim is available in "alternate law"? The only time auto trim is not functioning is in "direct law".

Airbus Flight Control Laws