This is phobia. Experienced American Airlines A321 captain's words after takeoff. Airbus doesn't do anything like that. During takeoff from Newyork for 14 to 17kts crosswind suddenly kicks left rudder from 8° to 25 degree causing more than 30° bank and hits runway marking board during rotation which permanently bent the wing leading to a write off. They almost lost control could have crashed. It's simply ridiculous.

vilas... " Anyway it's too late to discuss unreliable speed as Airbus now has mathematically calculated airspeed which they call it digital back up speed. This doesn't require any anemometric input. This supervises the ADR calculations and in case of all ADRs going rogues their speed indications are replaced by the Digital Backup Speed. A350 does it automatically A320 does it through ECAM actions. ​​​​" ​​​​​​​​​​​​​​​​​​​​​ Is that BUSS? Back Up Speed Scale? An option on A330, which Air France took a pass on?​​​​​​​​​​​​​​ ​​​​​​​Still goes to ALT LAW 2 B ??​​​​​​​​​​​​​​​​​​​​​​​​​​​​ Begs the question, should duff IAS have trIggered a change to ALT LAW ? Much ado about a condition that needs merely Pitch and Power? ALSO, AoA is the critical instrument? Where was the AoA instrument? Right, not equipped with one...​​​​​​​How much money did Air France save on F-GCZP....?​​​​​​​​​​​​​​​​​​​​​​​​​​​​
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No! Backup speed scale is an older mod. It doesn't calculate speed just shows a green band like TCAS to fly based on AoA. That also came after 447 as a remedy. Digital back up speed is actual speed displayed on speed tape that pilot flies. It is calculated by injecting weight, load factor and AoA in lift equation. It has different indication for pilot to know it's calculated speed.
​​​​​​​

Long time coming. Is anomometric the new back up?​​​​​ So. Flight into known icing with triple redundant pitot probes known to be susceptible to packing up in an Aircraft that would likely startle our flight crew is not criminal? (Rhetorical)..... thanks vilas, much respect​​​​​​​

Hmmm
 

punkalouver "Many of us are not fully aware of how we will react under various surprise scenarios. Sudden surprise encounter may be the the important factor."

Holy. S. ​(Sacre. M.)​​​​​​ ​​​​​​​​​​​​​​​​​​​​​​​​​​​​

punkalouver..."A dash-8 pilot flying into Buffalo encounters an artificial stall warning well above the stall speed because of a misconfigured stall warning system."

The Stall Bug had been set for Anti Ice. FO switched off Anti ICE, but neglected to move the Stall Bug associated with the system.Captain had assumed the higher Stall trigger was now set for an actual Stall... Still, why did he pull? He didn't. At least not right away. ColganAir SOP for low level STALLWARN was "Minimize Altitude Loss, Full Power". Which, oddly enough, was Air France's also. Cannot push, and minimize altitude loss... As I recall

He pulled instantly and kept 50-100% back pressure on column until he killed everyone 27 seconds later. And the FO put the flaps up unprompted.

You know nothing about what you’re talking about and are an excellent troll.

Here is the digitised FDR/CVR video produced by the NTSB which demonstrates your total ignorance.

He has a long, long history in that regard.

​​​​​​​What Air france delayed installing was not the BUSS because it was simply not deviced yet. Actually BUSS was thought of because of AF447. To my knowledge the pitot static equipment which was installed on AF was prone to icing and a better euipment became available which they delayed installing. Stall warning comes fro purely AoA speed has nothing to do with it. But the low speed stability in alternate law which pitches the nose down comes from speed. When speed is not available control laws change to alternate2 which looses the pitch down capability but stall warning remains available since it comes from AoA.

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I came across the YouTube video below from a PPRune forum a couple of years ago. The video does a great analysis of startle factor & how we, as humans, are wired. It is well worth the 30 minutes of viewing time in my opinion.


Cheers

VH-MLE

If the stall warning was purely from the AoA sensor, why did the warning cut out without a large attitude change in the aircraft?

Because the stall warning is inhibited below 80 knots (IIRC) indicated as no one would ever try to fly that slow. That prevents nuisance warnings on the ground when the aoa vane droops due to low/zero airflow.

The only time the back stick was released the speed increased above the inhibition threshold causing the stall warning to restart. The PF’s response was to pull full back stick again which slowed the aircraft back below the threshold causing the stall warning to stop again.

Triggering of stall warning is from AoA. But below 60kts the system takes it as non computed data and rejects the input to stop the warning.

I guess my question becomes why would indicated airspeed have any effect on STALLWARN.​​​ Was AF447 having AoA sensing issues as well? Much has been made of the change in flight law, seems a serious outcome to have for the cockpit to go sideways due to iced pitots? Roll Direct especially? In turb? ​​​​​​​sorry if this is a dumb question? ​​​​​​​thx vilas​​​​​​​​​​​​​​

No. The aircraft had a temporary issue with the ASI’s that recovered quickly and to any competent pilot an ASI is a convenience item. You can easily fly without any speed indications.

The rest was pilot error. Huge errors.

That is an excellent video. I've flown into Duxford many times as a PPL. Food for thought. Much to learn.

Agree... So I guess the next question is why did the AC computer invigorate the STALLWARN? And change (degrade) FlightLaw ? The computer reacted as it did due to malfunctions of a convenience instrument? "Seeking to understand is not seeking to exonerate..."

Thank you for your response....!​​​​​​​

The computer system is designed with the concept that only 1 subsystem will fail at a time. It determines this by comparing the outputs and using the output that at least 2 of 3 agree (within some tolerance) on. In the case of the ice accumulation, one pitot tube plugged - that left 2 in agreement. Then another pitot tube plugged leaving all 3 in disagreement as the stored pressure would have depleted at different rates due to the moisture bleed port.

That's what triggered the change in control law - the system had 3 different opinions on what the dynamic pressure reading was and there was no winner.

I think the stall came about because when the PIC was handed control he slightly pulled the sidestick back while trying to maintain roll orientation. At that altitude and airspeed the plane was close to stalling and the slight mishandling pushed it to give the warning - the pilot then did what would have been fine if the control law was "normal" and gave it full throttle (causing a hard pitch up) and pulled back, confident that the alpha protection would prevent the stall that was already occurring.

Once the altimeter started unwinding I expect that, even if it was noticed, it would take remembering "how an airplane flies" to convince the pilot to shove the nose down and increase the rate of descent in order to exit the stall and resume normal level flight. I think that at some point the pitot tubes cleared and if they had reset the flight computer it would have recovered hands off because enough valid data would be available. To do that would require knowing that the control law had changed - which the PIC did not appear to know.

MEgr
 

"I think the stall came about because when the PIC was handed control he slightly pulled the sidestick back while trying to maintain roll orientation. At that altitude and airspeed the plane was close to stalling and the slight mishandling pushed it to give the warning - the pilot then did what would have been fine if the control law was "normal" and gave it full throttle (causing a hard pitch up) and pulled back, confident that the alpha protection would prevent the stall that was already occurring."


Had the StallWarning been a result of temporary (close to) AOAcrit exceedance, he would have known the AC was in ALTLAW, right? He also would have known ROLLDIRECT was in charge of ailerons, right? The aircraft will NOT Stall in NORMAL LAW. Why would STALLWARN not be sufficient notice to pilots of a change in control action? If the STALLWARN Will sound in NORMAL LAW, would he not expect ALPHAPROT To control AoA?

Thanks for responding, food for thought.

Relying on the protections to prevent a stall has never been an SOP. Flight control protections are the LAST LINE OF DEFENCE, they should never be used to solve a problem because if they fail you’re screwed. That’s why the Airbus stall recovery has ALWAYS been to reduce AOA and accelerate, never “just pull back and let the protections sort it”. It is not a reasonable course of action for an Airbus pilot to gently pull back and let normal law protect you from a stall. The aim is to always fly inside the envelope but have protections if you inadvertently reach the edge, never to go intentionally to the edge and rely on protections to look after you.

There has been an industry wide change in emphasis (all a/c types) in recent years where before a consideration was to minimise height loss whereas now the priority is to aggressively break the stall then recover, as the new emphasis actually results in less height loss.

ahHAH.... "There has been an industry wide change in emphasis (all a/c types) in recent years where before a consideration was to minimise height loss whereas now the priority is to aggressively break the stall then recover, as the new emphasis actually results in less height loss." That makes perfect sense. If "Minimized height loss" was the goal, how to judge that? Especially when near the deck, even in the sim? Pucker ttime.This suggests to me that Approach to Stall on short final was done in Normal Law?? Wouldn't high altitude Stall Warning be "break the Stall? Many thanks, Locked door​​​​​​​

Don’t misunderstand, the priority was always to reduce AOA and increase thrust to end the stall and fly away. Previously the guidance was to recover the descent as soon as flying speed was achieved whereas now the guidance is to delay the recovery until the aircraft is really moving as some pilots were trying to recover too early causing a secondary stall.

The priority is, and always was, get the nose down and get the thrust on. What the AF pilots did is inexplicable.

What flight control law the stall training was done in is irrelevant, as the recovery is done inside the flight control envelope unless it is mishandled, in which case the training would be done again until it was done right. I suspect most training is done in alternate law as you can’t fly a recovery until the first sign of a stall, and you can’t achieve the first sign of a stall in normal law.

Locked door
 

"The priority is, and always was, get the nose down and get the thrust on. What the AF pilots did is inexplicable." So what we're left with is, were AB aircraft in Normal Law when practicing Approach to Stall down low? Training is important here, I think, the possibility for startle/confusion is clear, at least to this non big rig pilot ...

And..."I suspect most training is done in alternate law as you can’t fly a recovery until the first sign of a stall, and you can’t achieve the first sign of a stall in normal law." So, clearly PF AF447 knew the STALLWARN was legit, and he had to know they were in some type of AlternateLaw....which also means he knew AoA was a load factor request, and Roll was in DIRECTLAW...​​​​​​​​​​​​​​Thanks for your patience Ld​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

Actually, I'm pretty much convinced that the PF did not know he was stalled - it's simply inconceivable to me that a trained pilot who thinks they are in a stall would continue to hold full back pressure for several minutes while the altimeter unwound to zero.
I suspect he heard the 'You can't stall' and in the heat of the moment either didn't recall the 'in Normal law' part - and/or he never comprehended they were not in Normal control law. Further, he either didn't hear the "Stall Stall", or didn't comprehend it.
To me, this is a danger in telling pilots that you can't stall an aircraft unless it is in fact physically impossible to stall it (there are a few aircraft designs where the basic design precludes being able to get it into stall - I think the 'Verieze' falls into the catagory) - because in a startle/panic situation they may not recall any provisos to the 'can't'.

Agreed. The PF suffered from a fatal combination of poor training and/or systems knowledge.

I also have a theory that he also suffered from automation dependency. He was just trying to keep the FD centered, because he’d never flown without them.

Aren't the Flight DIrectors "OFF", either automatically, or turned off as a checklist item in UAS? From the CVR. "I have no vario..." (VSI).​​​​​​​ So if he mistrusts vertical speed, his descent is not acknowledged until 4000 feet: "We better pull, we are at 4000..." ​​​​​​​Afraid I rely alot on what and how they talk on CVR....it is the only eyewitness account we have. For good or ill, it suggests they (all three) never understood the airplane..​​​​​​​ Except at the end of the recording...​​​​​​​Captain: "Pitch ten degrees...." Then impact...I have a theory why he said that. He was one of the first at the accident scene...it was a witness statement...​​​​​​​

The FD's disappeared with the data loss, and then reappeared at +6000 fpm. You betcha he was following the FD with soda-straw vision on the one item most burned-in as the main concept of flying the airplane

Vessbot
 

Fair enough...were they reliable? That's an important question.... who flies stick and rudder in an electric jet?

Ever since AF447 happened and till the final report came out and even well after that this subject has been beaten to death with over 30000 posts till it was closed. And we are starting afresh treading the same path again.

If it all gets too much of a repetition, we can lock it. However, let's leave it run for a little while to see if it dies a natural death first. If it gets onto generic matters there may be some training and/or learning value ?

The discussion cannot add much to technology that existed in AF447 because in the past thread it has been thoroughly analysed, questioned, even misquoted and subsequently corrected. What the pilots did and why did they do what they did also has been discussed. The process went on for years. So there was nothing left to learn. Now the only interest should be what has Airbus done to avoid repeat or improve the outcome. With the latest modification it's virtually impossible to repeat 447 because in A350 it deals with it automatically without any pilot intervention and provides alternate speed to fly. In other aircraft like A320/330 it's auto detected and pilot is provided with actions to switch to alternate speed. So UAS now only is an issue with unmodified aircraft or aircraft with older modification where pilot identification of the situation is necessary before using the modified display to fly.

Amen to all the above; the 350 can even utilize the data being fed to the engines as additional back up. And GPS altitude. So, very clever in a Sorbonne kind of way and Airbus has moved on. Hopefully training organizations, airlines and pilots for that matter have as well by adopting regular exposure to UAS scenarios and unreliable airspeed. The 330 checklist for unreliable airspeed is very difficult to simulate, as by definition the very scenarios that you’re trying to emulate are nebulous and subject to change.
So it takes a very good instructor to run those sessions, understand them properly, teach at the same time and, demonstrate the procedures. Not just a question of activating the BUSS, although that does tend to be the final result. I can’t speak to the other Airbus types. And team B seemed easier overall.
At the end of the day it’s back to the old recall drills of pitch and thrust; in the old Jumbo it was 2 and a half, two and a half, and two and a half. 2.5 units of pitch, 2.5 units of thrust on the thrust resolver scale on the quadrant, 2.5 on the standby or other AI…. all derived from different sources. Will that maintain level flight at all points of the envelope ? No. Prob not. It will however prevent you pancaking an aircraft in to the sea. AIB have similar drills, dependent on stage of flight, take off, climb etc.
This thread should be laid to rest; some of the comments from the OP ( in particular about stall recovery procedures ) are frankly trollworthy and show us in a bad light.

Lots of people do. I think you should read the full accident report. You’ll find a lot of information there.

Out of curiosity, did Airbus modify the stall warning logic, ie the 60kn lockout?

The dust has settled on this accident; time to look at the residual patterns in this and other complex events.

Consider the human; not stick and rudder skills. The crew were qualified pilots; more training for them implies more training for all qualified pilots. If not why not, why would we be different.

The indications are that in this incident and similar, the circumstances exceeded human capability at that time in that situation. It is difficult to change human limitations, so change conditions of work.

Modified pitot tubes. BUSS recognises the importance of speed in surprising, albeit temporary situations. New research on how to alleviate the limitations of 2 out of 3 logic if all three systems fail (EASA).



Designing for Situation Awareness in Complex System

https://www.researchgate.net/profile...ication_detail

Note: "Expertise, therefore, can be seen to play a major role in the SA process. For novices or those dealing with novel situations, decision making in this environment will be an arduous task, requiring detailed mental calculations based on rules or heuristics, placing a heavy burden on working memory."

Expertise / novice relates to individual capability, not total flight time or which seat you sit in, it involves what is known (know what and know how), what can be recalled and related too in exceptional circumstances.


The Effectiveness of Airline Pilot Training for Abnormal Events

http://journals.sagepub.com/doi/pdf/...18720812466893

"… during a real flight, pilots’ responses frequently differed from accepted standards and showed greater variability."


An analysis of flight crew response to system failures

https://www.yumpu.com/en/document/re...ystem-nlr-atsi

"The results show that in 17% of the sample, crew response to system failures was inappropriate. The percentage of inappropriate flight crew response decreases from 25% for earlier generation aircraft to 4% for the newest generation.
The percentage of inappropriate response shows differences when various systems are compared, the lowest percentage of inappropriate responses occurs for flight control system malfunctions (8%), the highest percentage for instrument failures (48%). 11% of the investigated cases of inappropriate flight crew response involved wrong detection, 38% involved wrong diagnosis/decision and almost 51% involved wrong action.
Annunciators have a pronounced effect on the probability of failure detection.
Inherent cues play a relatively large role in decision failures. Inherent cues such as vibration, loud bangs etc., can be compelling, but are often not very conclusive or even misleading."

They didn't need to get rid of the feature, just emphasize that it is there in the first place in case someone else tries to recover from a stall when they're already under 60 kts.

Salute!

Thanks, JT, Td and vilas.

Many lessons to be honored with that tragic crash, and prolly more than crew coord, systems knowledge, side stick implementation, and such.

When I first read the CVR beside the FDR I cried... screamed at those guys. The first pics of the plane on the floor of the sea hit me as something from my past. I had been there ....... you know, you can not stall this plane, why am I going down so fast but the plane is not shaking or rolling a lot, and horns are going on and off.... Oh well....

I would invite those who wonder what some of us are talking about, then go to the closed thread and wade thru all the opinions, real world experiences and the technical stuff. Otherwise......

Gums sends....

alf5071h , 29th Mar 2023 07:14"The dust has settled on this accident; time to look at the residual patterns in this and other complex events. Consider the human; not stick and rudder skills. The crew were qualified pilots; more training for them implies more training for all qualified pilots. If not why not, why would we be different."

What a breath of fresh air. I couldn't have put it that way in a million years . (Obviously?) I have tried to ask questions from the point of view, (not that I could ever imagine the level of emotions) of the flight crew, shocked, puzzled, angry, etc. ​​​​​​​​​​​​​​frustrated.​​​​​​​ ​​​​​​​You put it well...and I am personally grateful. ​​​​​​​I have learned, alot. Thank everybody for every post. Every one....​​​​​​​

I'm not sure what you mean by considering the human without the stick and rudder skills, as it applies to this. The crew were qualified pilots in the sense of an official requirement being met by a bunch of boxes being checked, but lacked the stick and rudder skills necessary to meet the situation. To more training being required for them implying more raining being required for all qualified pilots, yes and yes.

All that was required was indoctrination (even on ground would do) that when in alternate law at cruise level you leave the pitch alone and just keep wings level and if pitch change is required don't make it without looking at PFD to ensure that the pitch is below 5°.