AF447 wreckage found

[alenka]

Third interim report, 29 July 2011 (published in English on 4 August 2011)

http://www.bea.aero/docspa/2009/f-cp...90601e3.en.pdf

[airtren]

I have not followed the Stall Warning discussion on this thread earlier, so I apologies for my delayed questions:.

It looks like the STALL Warning OFF, coincides with Pitch NU increase, while STALL Warning ON, coincides with Pitch ND decrease.

What caused the pitch attitude variations?

Originally Posted by DozyWannabe

2:10:12 - *bang*

2:11:55 - *bang*

2:12:08-10 - *bang*

2:12:28 - *bang*

2:12:33 - *bang*

2:12:40 - *bang

2:12:48 - *bang*

2:13:52 - *bang*

2:14:20 - *bang*

I rest my case.

[airtren]

I concur with the thought that knowing the sharing the information about the stick actions in the cockpit is a good thing. In the AF 447 case, it would have allowed the PNF know exactly what the PF was doing, in Phase 2, and Phase 3, which were both critical.

A 3D animation of the stick, shown on a screen could be one way to do it.

Originally Posted by CONF iture

No Dozy, the PROBLEM has always been to know IF and HOW your partner makes flight control inputs.

[DozyWannabe]

Originally Posted by xcitation

DW
are you saying that the nose ups did not cause the stall warning.
Are you trying to correlate stick inputs to warnings.

I'm trying to say that the stall warnings do not coincide with inputs, but with the attitude of the aircraft (which did not always correspond with inputs due to it's stalled state).

Originally Posted by airtren

It looks like the STALL Warning OFF, coincides with Pitch NU increase, while STALL Warning ON, coincides with Pitch ND decrease.

Really? To me it looks like (after the stall) the Stall Warning comes on as the nose begins to pitch back up, then switches off as the pitch-up causes the aircraft to assume an extreme AoA and slow down again. Then the nose comes down again, a little speed is picked up and the stall warning comes back on as the nose starts to come up.

What caused the pitch attitude variations?

Aerodynamic forces present in the stall, in combination with the position of the flight control surfaces at the time. If you've ever made a paper aeroplane and thrown it while pitched nose-up, you'll remember that the nose went up, the paper aeroplane stalled due to the high angle, the nose came back down and usually it made a change in direction of some kind as it fell to the ground.


Either way the path was not always under the control of the pilots, so my view is that while the stall warning logic is unsatisfactory in this extreme circumstance, I believe that if the stall warning did contradict or reinforce pilot behaviour, it was a coincidence rather than a consequence (note the nose going down several times while the PF's SS is back at the stops)

[Fox3WheresMyBanana]

I have some experience lecturing on FBW flight controls, and instructing in a simulator. Aircrew tend to follow A drill, rather than do nothing. The usual reasons for following the wrong drill are rushing into action based on only one or two bits of information (probably the audio warning and the speed readout failure in this case), reverting to type (flying the aircraft/action they are most familiar with, e.g. TOGA loss of IAS), and forgetting the nasty little corners of the aircrew manual (no stall warner below 60kts in this case).
All three reasons for doing the wrong thing are present here.

I've also been hit by lightning IMC in the dark at 30-odd k and lost instrumentation/aircraft systems/AP. It's very disorientating, as would all the loud noises be to them. Add the bumps and you have no physical sense of what the aircraft is doing. Very easy not to recognise the stall in this situation. PNF should be cross-checking and isn't.


Power, Attitude, Trim.

The PF is flying for 15 degrees NU, power is variable as he's not sure of speed. There's no trimming, probably because he's forgotten it.

In fact, I think he's going for at least 12 degrees Nose-Up attitude right from the start of the problem.

Question please, doesn't everybody memorise the Power/Attitude combinations for t/o, climbout, cruise, descent and approach any more?

This situation should have been met with.
Take control
Set 2.5 degrees nose-up attitude and 90% power.
Cancel warnings, identify loss of IAS readouts.
Get PNF to confirm diagnosis.
Run through drills.
Recall Captain to flight deck.

What it's met with is:
Take control
Fly unreliable IAS drill calling for 12/15 degrees nose-up attitude
Push power up when stall warner sounds (instinctive)
No correct communication with PNF

I do think the Captain's failure to formally divide the tasks before leaving the cockpit is important to the last point.

[RWA]

I think maybe most of us are being a bit 'unfair' to the pilots. The FDR/CVR confirms that, for just about all of the time, they didn't have speeds - and both the Flight Directors kept cutting out at intervals, so very probably they didn't have working artificial horizons either for long periods. Indeed, late on, the Captain told the PF to use the ISIS, the standby instruments - that's clear proof, to my mind, that they literally couldn't see 'which way was up' (or, very sadly, which way was DOWN) from the normal displays.

Another thing that bugs me a bit is that the 3rd. report confirms without qualification that the THS, as reported earlier, went to virtually 'full up' at the outset and stayed there for good. Despite the fact that there were nosedown inputs at intervals. It ALSO confirms that in Alternate Law autotrim remains in operation.

Been thinking a bit about trim. In the stuff I flew (mostly gliders) it was an 'aid' only - it didn't 'think.' Generally speaking, if you wanted a sustained climb or descent, you moved the stick and then adjusted the trim until the stick forces were 'neutral' - when you wanted to level out you did the same thing over again. Point was, the trim was the servant, not the master.

The autotrim in Airbuses (maybe Boeings as well, for all I know) appears nowadays to go ON adding trim (up or down) after an up or down command unless and until the pilot makes an 'equal and opposite' movement of the stick. I just don't think that's sensible or necessary.

Another factor is Airbus's practice of not providing sidestick feedback. As indicated above, I simply don't know how anyone could fly effectively (not 'seat of the pants' stuff anyway) without it; seems to me that Airbus pilots (Boeing still provide feedback, albeit artificial) are permanently 'flying IFR' at present.

Yet another thing is the sidestick idea in itself. It virtually guarantees that neither pilot (plus the captain in this case) can see what inputs the other guy is actually making; they have somehow to work it out, after the event, from what the instruments show (IFR again). Monitoring what the other guy is actually doing is no problem with the traditional yoke or 'stick between the knees.'

Very much hope that Airbus review their whole 'design philosophy' about sticks etc. (especially the 'feedback' issue) as a result of this accident (plus others, like the Perpignan one). I believe that the spring-loaded, 'no feedback' sidestick was originally introduced purely as a weight-saving measure. Might be a good idea to reconsider that decision, even if it does mean a few extra pounds of weight?

[JJFFC]

The adolescent, his brother and his father

Apart from technical issues, let's deal with the psychology and procedures:

- Should the captain have leave his seat to an adolescent yet he had a bad feeling ("Do you "really" have your licence ?"), furthermore in front of his girl friend ?

- Does it exists a procedure that the Capt. didn't followed that would have prevented him from leaving his seat to an adolescent ?

- Does it exists a procedure that could have allowed the PNF to take control by strengh after the PF has re-taken control without annoucement yet the PF had admitted having lost the plane ?

- Is there a procedure that would have allowed the Captain, when entering the cockpit, to understand that the problem was dealing with the PF mental attitude ?

- Is there a procedure that would have imposed him to discharged the PF and take control or give control to the PF ?

Thank you

[amos2]

1. no
2. no
3. no
4. no
5. no

[Neptunus Rex]

JJFFC

Yes, there is a 'procedure.' It is called Airmanship.

[grimmrad]

What also strikes me is that at no time someone mentions they are going down i.e. going to crash. They state arriving at 100 but no where do I see a human reaction like "oh my god we are going to..." or something alike. Did they not realize it? Probably good for them but maybe not good for their plan of action (survival mode)?

[GerardC]

But there are thousands of Airbus FBW pilots around the word that do not consider it a problem - this is not about *my* opinion, this is about *theirs*.

Yes Dozy, but there are thousands of pilots around the world that have NO other choice than flying yoke-less a/c.

I recently had a chat with a free-lance captain with both A320 and B 737 ratings.
He told me "when all is OK Airbus is better. In crosswind, windshear, if something goes wrong etc... B is better".

It is clear from cockpit dialogue that neither PNF or Captain (when back) had any idea of what the PF was doing with his SS.

You cannot dismiss this is a true problem.

[DozyWannabe]

Originally Posted by RWA

...both the Flight Directors kept cutting out at intervals, so very probably they didn't have working artificial horizons either for long periods.

The Flight Director is a digital overlay on the ADI - non-presence of FD does *not* indicate that the AH component is not working.

Indeed, late on, the Captain told the PF to use the ISIS, the standby instruments - that's clear proof, to my mind, that they literally couldn't see 'which way was up' (or, very sadly, which way was DOWN) from the normal displays.

He says "Horizon - Standby Horizon", which could just as easily indicate that the two are in agreement and he is drawing their attention to that fact.

I believe that the spring-loaded, 'no feedback' sidestick was originally introduced purely as a weight-saving measure.

Not at all.

Monitoring what the other guy is actually doing is no problem with the traditional yoke or 'stick between the knees.'

Knocking the A/P out by bumping and getting foreign objects jammed in the traditional yoke or "stick between the knees" have caused accidents in the past too - it's not all one-sided.

Very much hope that Airbus review their whole 'design philosophy' about sticks etc. (especially the 'feedback' issue) as a result of this accident (plus others, like the Perpignan one). Might be a good idea to reconsider that decision, even if it does mean a few extra pounds of weight?

Of course, why not just throw away years of development and just make planes the Boeing way to satisfy a minority of pilots who can't deal with having the training wheels off? Yeesh...

@GerardC - that's fine but it's only one pilot's opinion. There are a fair number on this very forum who don't see the lack of backdrive as a problem because they have other methods that compensate for it. Also, as I've said more times than I care to recall, the A320 flight deck and controls layout didn't stop Sully!

[Fox3WheresMyBanana]

Without wishing to sound facetious, couldn't the PNF have asked the PF what he was doing?

I would have thought it's his job to.

Not doing so certainly turned out to be more than his life was worth.

[martinhauptman007]

Here is what an A330 captain said about the crash:

The key ingredient most everyone seems to be overlooking: The flight control laws of an Airbus. An Airbus has flight envelope protections that cannot be overridden by the pilot. This is almost always a good thing because the airplane won’t allow the pilot to overspeed, stall, overbank or overload the airplane. In the peculiar case of [Air France Flight] 447, the airspeed reading was inaccurate because the pitot tubes were blocked — a very rare occurrence in a jet — almost never happens.

But when it does happen, the airspeed then acts like an altimeter: When the airplane climbs, the indicated airspeed increases, and when the airplane descends, the indicated airspeed decreases. My best guess for AF447 is that the airplane was climbing, most likely due to turbulence; I believe they were in a thunderstorm. From a pilot’s perspective, this is a bad place to be. It’s rough and difficult to read instruments. Autopilot disengages due to turbulence or ice on the airframe or pitot tubes. The airplane is climbing, and the pilot is wondering what the **** is going on. Then, as the airplane climbs, with the false readings still indicating increased airspeed, at high altitude the margin between cruise airspeed and overspeed becomes very small, so the airplane overspeeds — or so it “thinks,” due to the false reading. And it’s at this point, provided all of this is what really happened, that they’re ******.


Think back to the Airbus flight envelope protections I mentioned, and the fact that the pilot can’t override them. The airplane computers “think” the aircraft is overspeeding and therefore continue to increase the airplane’s angle of attack. That only makes it climb steeper, thus perpetuating this cycle of increasing indicated airspeed and increasing angle of attack. This continues until the airplane is at a ridiculously high nose-up attitude and stalls, regardless of pilot inputs.

This is why we really need to wait for a full analysis, so that investigators can figure out what the pilot inputs were and whether or not they were consistent with what the flight control surfaces were doing. In other words, were the pilots ******* up the control deflections, or were the Airbus flight computers ******* up the control deflections? Because the airplane eventually stalled, I can only surmise that it was the computers ******* up, because when the computers do their jobs correctly, they increase angle of attack in this situation — again, regardless of pilot input.

So the airplane stalled. One plausible theory is what I just described. (There are other scenarios in which the flight control laws are degraded and the airplane can stall under certain circumstances, but that’s a whole other set of seriously complex stuff. Who knows though? Maybe that’s actually what happened.) Even if this guess doesn’t explain precisely what took place, it constitutes a design flaw in the Airbus that needs to be fixed in that the flight envelope protections need to be disabled if they’re receiving inaccurate information.

Source:An Airbus Captain s Take on the Air France Disaster

[Victor2]

Management of Risk

A bit late in the day but thought that I would make an observation!

Apparently neither pilot was trained in high altitude flight. If that was the case they would not have practiced stall recovery in that regime. Neither is is logical that when pilots spend 60+% of their flying in this environment such an omission is tolerated.

Safety in aviation is usually calculated reference to the risk ratio of 1 in 10 to the -6 or 10 to the -7 depending on the critical nature of the system under consideration. The reliability of the airspeed sensors would come into this consideration i.e. the likelihood of failure is extremely remote. This all changes when such an event occurs. This was apparently the case with the A300 where such previous failures had occurred and a "fix" was in the pipeline.

While it would not be reasonable to stop all operations while "the fix" was being manufactured and incorporated, it would be more than reasonable to join the dots and realise that the reduction in risk should be ameliorated. In this case by highlighting the situation to the crews and by providing additional training to recognise and deal with the problem itself and the possible outcomes. In my view this is not "the benefit of hindsight" it is what management of safety and risk is all about.

[DozyWannabe]

@martinhauptman007 - Unfortunately the aircraft was neither in an autoflight regime, nor did it have active hard protections (due to Alternate 2 Law caused by the blocked pitot tubes). So that article is misinformed.

[RWA]

Quoting Dozywannabe:-

"Of course, why not just throw away years of development and just make planes the Boeing way to satisfy a minority of pilots who can't deal with having the training wheels off? Yeesh..."

Fair enough in its way, Dozy, mate.

But looking at it another way, for a bit longer than aeroplanes have been around, bicycles have. It would be perfectly possible, with today's 'electronic aids,' to design a bicycle that didn't need handlebars; so that the rider could turn just by 'body lean,' with his/her hands in their pockets....

But no-one has yet designed a bicycle that works that way. I'd venture to say, because yer av'rage rider would get a bit confused......

So precisely WHY, in your opinion, did Airbus opt for 'no feel/no feedback' etc.? A revolutionary change, after the best part of a century of producing aeroplanes that all 'worked' the same way?

My own view is that it was a matter of 'less weight/lower cost.' I can't think of any other reason?

Maybe you can?

[bearfoil]

xcitation. Way too early for this, I warn. In the desription of fox3banana I see a Pilot (if description is accurate), displaying some troubling issues.

First, there is a friction in the PF/PNF dynamic. PNF has taken role of leader.

Second, PF appears unwilling to admit mistake, and "insists" on taking control.

He appears to act without "executive function", internally.

Oppositional, lack of executive thinking, and poor impulse control.

This is admittedly unsupported, and I apologize for even bringing this to the front. However, the investigation might seem to be heading into a Human Factors/Dysfunction moment.

Understand that the situation is incredibly challenging. I have experienced panic while flying in wind shear, and it took all the energy I had to properly focus. These guys had one hurdle after the next, and many all at once. Each person can revert to less than effective performance when in this sort of challenge. That is why the sterile cockpit, Alcohol rules, and distractions are taken so seriously.

Astronauts (Used to) undergo extreme Physchological evaluation; some of the testing was barbaric.

No authority can loosen these rules for those entrusted to transport People by Air. We cannot let a loosening of flight chsallenges to degrade stress/performance requirements.

No criticism intended, and it may be only that this Pilot did not bring his "A" game to this flight. That is as far (and as lenient) as the situation can allow, for the sake of safety.


RWA Have you ridden a SEGWAY scooter? Two wheels, the handlebars are to support only your arms, and it turns by the cg change of your body.

It's been around for many years.

Also. FBW. It is early, but the HUMAN BRAIN has been shown to change tune a radio by wirelessly comanding the change by "thinking". I kid you not. "Mind command" is not far off. With the fine tuning of the kit now working, it is conceivable a pilot may fly without touching anything! It also warns to be very very cautious of distraction?

AIRBUS. RWA, don't leave out another motive for a "change" in flight controls. Complexity for the sake of marketing. NEW!! DIFFERENT!! CHEAPER!! and did we say NEW!!

[airtren]

Thanks again for posting the graphs.

If one plugs in the Stick and Thrust graphs as well, one will see that on the Pitch graph the Pitch Nose Down, and Stall Warning OFF/ON/OFF corresponds to either Thrust action - reduce Thurst - or Stick action ND, or both. Thrust and Stick variations after the A/THR disconnect are both PF/NPF actions.



This brings Pilot action (thrust and stick) into correlation with all 10 OFF/ON/OFF Stall Warnings that occurred bellow FL350.

Regarding the interpretation of "coincidence" rather "consequence", it may be suffice to wonder if it really makes a difference, as the result was the same, one way or another: an addition to the other factor(s) of confusion.

While the reasons of the limitations are understood, with a systems engineering hat on, a behavior similar to the Stall Warning, would be ennoying if one had it on his car, or computer, or TV, or some other appliance, etc.... and would want it fixed. And sadly, one certainly would not want to have a chance to have it at all, in a "Hospital Surgery Room" or an airplane cockpit, in a critical life or death situation. (sad)

Originally Posted by DozyWannabe

I'm trying to say that the stall warnings do not coincide with inputs, but with the attitude of the aircraft (which did not always correspond with inputs due to it's stalled state).

Really? To me it looks like (after the stall) the Stall Warning comes on as the nose begins to pitch back up, then switches off as the pitch-up causes the aircraft to assume an extreme AoA and slow down again. Then the nose comes down again, a little speed is picked up and the stall warning comes back on as the nose starts to come up.
....
Either way the path was not always under the control of the pilots, so my view is that while the stall warning logic is unsatisfactory in this extreme circumstance, I believe that if the stall warning did contradict or reinforce pilot behaviour, it was a coincidence rather than a consequence (note the nose going down several times while the PF's SS is back at the stops)

[CONF iture]

Originally Posted by DozyWannabe

But there are thousands of Airbus FBW pilots around the word that do not consider it a problem - this is not about *my* opinion, this is about *theirs*.

... surely you must therefore consider that the theory which supports your personal preference may not necessarily be the solution in all cases?

Let them have their own voice then ... In this AF447 time, not too many Ziegler on the board I must say.
Never seen it as THE solution - Just a waste of a very valuable source of information.

Also, as I've said more times than I care to recall, the A320 flight deck and controls layout didn't stop Sully!

What's your point here ?
Don't mix everything.


The bare minimum I would expect to read in the findings (and I'm not even talking about recommendations) :

• The sidestick ergonomy as implemented by Airbus deprieved both PNF to actually realize what control inputs were applied by the PF.

But BEA is absolutely unable to formulate anything in that direction.