Desitter :- 228 people went to the bottom because a pilot hearing a stall warning pulled the stick back. Given the pilot's actions. a Sopwith Camel in this event would have have had the same outcome, except the Sopwith wouldn't have been screaming "stall" in his ear.

Everybody talks now about the pilot`s performance , but it`s not economic interesting to talk about the 2 F/Os.

If instead of 2 F/Os they had 2 Capts and 1 F/o how it was years ago, probably they had more chances.

Aviation is a big more or less.

Absolutely agree.

This accident looks more and more like a flying skills issue, rather than design or software issue. And by implication an Air France training problem.

It falls under the heading.. "Flight with unreliable airspeed."

In general terms if you suspect that you have "unreliable airspeed" as a pilot, you stick to "datums." Put the power at a sensible figure, and set the attitude at a sensible attitude for that phase of flight. That will keep you safe. Having settled that down, diagnose the problem.

Plane, Path, People. .... or similar.

What you do not do is plant the sidestick in the back stop and expect a good outcome.

Thoughts on the initial climb and later, the implications of deep stall.

• Alt 2 is a roll direct law. This means that the pilot flying will have to control bank angle. Only the aircraft's natural stability will tend to level the wings. Any turbulence will impart a bank angle until corrected.

1. If PF had to fly the wings to keep them level, could he have inadvertently pulled the stick back while making corrections, either through nervous tension or bad personal geometry?
2. And could his instrument scan have been so rusty that he didn't realize he was inducing a climb?
3. Was there anything unusual about the copilots' stature, or technique in gripping the stick? (Realizing we ourselves don't really know who was PF but some guesses can be made).

• Although ACARS does not specifically state that the aircraft later switched into Direct Law, and BEA has not told us (yet), It appears that after a significant period of deep stall, the AOA and A/S on all 3 ADRs had to have been considered unreliable by the system. How can even one Prim stay operational in this situation? If all 3 Prims are not available, the aircraft must be in Direct Law. That would explain the pitch trim staying at 13 degrees after the aircraft actually achieved a deep stall.

Good math, poor aeronautics :-( Groundspeed is the horizonal component of the (inertial) velocity vector, if the airplane is going straight up or down, groundspeed is zero. Vertical speed can be either airdata (baro pressure) or inertial, the differerence between the two would be vertical wind components (up/downdrafts).

Sound asleep? Smooth ride?
 

If the pilot resting had to be called to the flight deck by the PNF, does this infer that the plane wasn't doing anything abnormal, at that point, that would have alerted the sleeping pilot?

Many have asked why the PF continued to pull back as the plane descended since it clearly indicated a stall. Maybe the FO disregarded the Altitude/VS data as well. Consider this:

He almost certainly would have disregarded any airspeed indications, so he's already thinking there's a pitot problem. Next thing he knows, the VSI varies between +7000 and -10,000. He's never seen those values before. Could he have assumed that the entire pitot-static system had gone bad?

The poor fellow now resorts to his last instrument- the attitude indicator. When he pulls back, the stall warning goes off, release the back pressure, and it returns. Catch 22 in his mind. Even if he knew that the stall warning would disappear below 60kt, if he had any idea that his airspeed was indeed below 60, he would probably have reacted more appropriately.

They probably put it all together when the RA started functioning and gave a "TOO LOW TERRAIN" alert, but at 10,000fpm, 15 seconds wasn't nearly enough time.

It must truly have been horrific in the cockpit. Flying in IMC, and none of your instruments or control inputs making any sense. RIP.

Bearfoils earlier post



What would explain the need for constant roll left, to maintain SL?

damage? AIR ? cg? Likewise NU? cg? ICE? All we see is the response, not the stimulus.


Whilst I can visualize the stall I cannot understand the aileron inputs.

The possible causes are updraft/turbulence - very unlikely at altitude in my experience.

Dutch roll - wrong duration of control input.

Asymmetric ice accretion ??? doubt it but..

flight control fault - side stick - computer or hydraulics or roll damper.

If the published data is correct and the aircraft wasn't in a stalled condition then 30 secs of full sidestick in a non protected aircaft should see it upside down.

My money is there is something missing which confused the pilots even more.....

Forgive my ignorance if alternate law will stop this happening - I didn't fly the bus although I had the chance.

Abnormal Attitude Law
 

Hi Check Airman,

I tend to agree. In just 46 seconds (between 2h 10 min 05 and 2 h 10 min 51) the aircraft climbed with ROC up to 7,000 ft/min from 35,000ft to “37,500 ft and the recorded angle of attack was around 4 degrees.” (which is a sensible angle of attack).

They must have ridden in the updraught of a CB to climb that rapidly and still have flying speed. Subsequently, they encounter the downdraught, their instruments don't make sense, stall warnings come and go, and I think they have mistakenly gone for Wind Shear QRH attitude 17 degs with TOGA power.

Edit. Once they were in Abnormal Attitude Law, the Stab Trim remained where it was last. (In this case full nose up)

"The system applies an abnormal-attitude law in pitch and roll if the aircraft exceeds any of these limits in flight.......

Angle of attack > 30° or < - 10° (- 15° for A319 and A321 (??? for A330))
Speed > 440 knots or < 60 knots

The law in pitch is the alternate law with no protection except load-factor protection and without auto trim. In roll it is a full-authority direct law with a yaw mechanical.

When the aircraft has recovered from its abnormal attitude, the flight control laws in effect are :
in pitch : alternate law without protection with autotrim.
in roll : full authority direct law with yaw alternate law."

I think roll drops to direct in alternate law, but it is still a good question - if the aircraft was level it should stay that way. BEA don't indicate the cause of the first left roll - maybe turbulence, maybe the wing stalled, or maybe some input from FBW. They made a left turn shortly before - were they still in the turn when normal law dropped out, and what would that do ?

IMHO Air France seems set up to take the brunt of the blame along with it's pilots and procedures. We now know (it seems) that the least experienced pilot was at the controls when the :mad: hit the fan. This will be a hard pill for the public to swallow, and AF's reputation may already be in a downward spiral. Could AF be going the way of Swiss Air? It may just be heading that way.......

CVR crucial
 

When can we expect to see a transcript of the CVR - I would have thought that this is now crucial to a proper understanding of what the pilots thought they were dealing with.

Razoray
No AF will not go the same way as Swissair.

Everyone in SR was worried about flying with crossair but management was using cheaper pilots to undermine SR pay scales.

Unlike the French the swiss had no qualms about buying foreign expertise.

Air France will not fail as the government will always protect it financially and AF have a protected market as the average french citizen believes if it's not french then it's not worth eating, using or visiting.

Some rude articles come up in not so marginal media outlets..

Wait for notorious pre occupied Fox news to have a go on the french..

'Baby' pilot at controls of doomed Air France Airbus | The Australian

I'm afraid when I read all these comments about speed
 

Stall has nothing to do with speed : it has to do with angle of attack.

It's incredible to read at all those posts wondering about the speed.

A real pilot earing a stall alarm should not even care about the speed.

Stall alarm = nose down instead you are dead.

Airspeed and software
 

Hello,

I read yesterday a part of this thread about what to do when the airspeed is not available.

If, as said earlier in this discussion, the pitch and thrust behavior should give enough clues to the pilot to find a solution to the problem, why can't these clues be submitted to a computer, and have the computer calculate the airspeed from these clues ?

In other words, shouldn't the autopilot software be improved to take into account this calculation and enable the autopilot to go on instead of tripping off (1)?

In other words, imagine we are not talking about an airliner but about a costly military drone. Wouldn't you want the drone to come back safely when this kind of problem occurs and to develop the necessary software ?

(1) " the computers controlling the flight switched off the autopilot after becoming confused by conflicting speed readings, caused by the icing up of pitot tubes monitoring the plane's velocity" : Air France crash inquiry details pilots' battle for survival | World news | The Guardian ; "From 2 h 10 min 05, the autopilot then auto-thrust disengaged" :http://www.bea.aero/fr/enquetes/vol....mai2011.en.pdf;

Regarding the initial stall warning:

and
These two paragraphs make me wonder if the stall alarms were really spurious.
At that altitude the buffet margin at M0.82 for G - onset should be around 1,5 - 1,6g, maybe even lower given the fact that additional Roll input was commanded..
Also speed might already have been reduced to M0.8 at that point further reducing the margin.
Edit: Stall warning activates even before that, thanks @HN39 for the comment. /Edit
A firm Nose-Up input should be able to achieve this.
Please note: Protections were already lost at that point and the Stall warning appears to have been subsequent to the Nose-Up stick command.
Please also note the subsequent Roll inputs by the PF.
either they were in significant turbulence or it was a sign that the aircraft was already in the incipient stage of the stall. These big Irons with full wing tanks and immense roll inertia normally don't have much tendency to 'wobble'.

Not quite. quote: "In level flight at FL350 and M.82 the pitch attitude (=AoA in level flight - HN) was 2.5 degrees". AoA=4 degrees is approx. the stall warning threshold at M.8 and results in a normal load factor of 1.39. If that LF is maintained during 9 seconds V/S=7000 ft/min.

P.S.: OTOH, at FL375 and M.68, AoA=4° corresponds to LF=0.78, i.e. a reducing V/S. At 215 kCAS and 700 fpm the flight path angle is about 1° up, i.e. deck angle is 5° up.

Not the first one to question pilot response but how would you handle a stall warning with the HST at 13dg nose up ??

The use of rectangles and diamond boxes on page 8 and henceforth differs from conventional flowcharts where "yes" and "no" are usually written along the lines rather than inside boxes. In flowcharts, diamond boxes are usually used for questions rather than answers. The use of the green color in combination with the word "no" is confusing.

I´m very disappointed from latest BEA report.
It is not what it tells. Its about what they actually know and dont want people (either public in general, or aviation experts not belonging to their investigation) to know at this moment.:=

At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have no valid indications". At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%.
When,who and why the levers were retarded to IDLE?

Around fifteen seconds later, 2:12:17? the PF made pitch-down inputs. In
the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.

How long the pitch down inputs lasted? what effect was achieved?

At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred". About fifteen seconds later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said "go ahead you have the controls".
What inputs were being provided by each pilot?


The angle of attack, when it was valid, always remained above 35 degrees. The recordings stopped at 2 h 14 min 28.



We have to believe (faith based) their "new finding" "the inputs made by the PF were mainly nose-up", as BEA report doesnt provide the full sequence of pitch commands. It could even be pitch down input from 2:12:17 to impact, without being in contradiction with "history of flight" para.

I´m ashamed that they dont tell what dialogues were ongoing in the cabin, what diagnosis they achieved (either wrong or correct),...and lots ogf things BEA surely know and they hide.

bearfoil, #507

So do I. The first two items in the timeline, page 2 of 4:

2hr, 08, 07, state normal, where the crew decide to detour and reduce
speed, then, a long two minutes later, autopilot and autotrim disengage. So
what happened during those 2 minutes to cause this and initiate the
deadly sequence of events ?.

Load of rubbish in the Sunday Times this morning about a "baby" pilot.
With that and other reports, looks like Air France and the crew are being
setup to take the fall for this one. Of course, the BEA are professional
and dedicated to the task of finding the truth, but may be withholding
data for many reasons. They are under no obligation to report
anything until the investigation is complete, but the latest report looks
as significant in terms of what it leaves out, as what's included. Imho,
of course.

In summary, not enough data and we must all be patient, yet again :-)...

As I stated earlier: and in turn the formation of "Public Opinion"

Quote:

---

HE was one of Air France's "company babies": a dashing 32-year-old junior pilot - and a keen amateur yachtsman - who had been qualified to fly the airline's ultra-sophisticated Airbus A330 jet for barely a year.

---

:D

As a total imbecile (Joe Public and a passenger) - I would have EQUAL confidence in a 'newbie' or a seasoned Pilot, purely on the fact that I assume by and large you do not have idiots flying aircraft, and in fact I might even say a less experienced aviator may be 'safer' as one would expect them to be relatively studious about wgat they were doing.

IMO Sirgawain123's question is VERY good: Why were the throttles closed? What would be the intention of such a control input?

Secondly: it the THS was at 13 degrees, what effect would this have on level flight? Would balancing inputs be needed on the control column/stick to prevent the aircraft getting too 'tail down'?

Are there any indications so far that after the Captain arrived there was any dramatic change in control inputs (as if the Captain spotted something?)

Once more with my halfwit goggles on, it does sometimes seem that people are reading too much into these things. G-ARPI crashed because the droops were retracted and the aircraft was pitched to hold an incorrect (too low) airspeed, and multiple stall warnings and pitch downs were ignored and countered until the aircraft stalled. The point being the investigation strived to reason why the crew did not notice the droop retraction: and this accident was a catalyst for CVR to be fitted.

This is not to say CVR is not a valuable tool: but rather CVR of itself does not prevent the 'cause' of accidents - it may prove that a crew was having a disco at the time, or snoring away, but may also prove that they simply did not foresee the 'main problem' - looking at what has been released so far does it not appear to be the case that this is the situation?

I do not know more than I read here: stall warning= push down - watch altitude and pitch. The command inputs we are seeing so far tell us that exactly the opposite was happening: therefore that is the cause of the accident is it not?

I may be missing something, but it seems to me it should be possible to write software that would calculate air speed without pitot tubes (and without direct reference to ground speed). INS (or GPS) should be able to provide the airplane's longitudinal acceleration at any point in time. From that and the airplane's mass you could calculate the longitudinal force. Subtract the thrust you know the engines are producing, and you'll have the aerodynamic drag.

The variables needed to calculate drag are air density, drag coefficient, and velocity (airspeed). It should be possible to calculate the drag coefficient from the airplane's configuration and attitude, and the density from altimeter and OAT. Plug those into the formula with the known drag, and out should pop the airspeed.

Much easier done than said, I'm sure. But a simulator takes control inputs and a number of other parameters (including airspeed) and calculates (I assume) an acceleration from which it determines the airspeed in the next "frame." The software I'm envisioning would be similar, except that instead of starting with airspeed and calculating acceleration, it would start with acceleration and calculate airspeed.

While I'm on a roll, there may be a simpler way: monitor the effectiveness of control inputs. If the pilot or FBW commands a certain rudder deflection (for example), gyros and accelerometers should detect the resulting angular acceleration. From that and the airplane's polar moment of inertia, you should be able to calculate the force (sideways lift) generated by that deflection. That force would correspond with an airspeed.

That looks the only possible statement in the above post..

Speculations
 

The more I read, the more clear it gets: the poor guys failed to recognize they were flying a fully stalled plane, got absolutely scared by the bells and whistles blaring all the time, rocking wings, winding down altimeters, a panicked captain shouting instructions and simply frozen at the controls (or even worse, giving inputs that agravated the situation), failing to do the only thing that would have saved the day.
Pure lack of proper training, basic airmanship & situation awareness.
It's hard to admit that a lot of us could have reacted exactly the same way.

A perfectly flyable aircraft turned into a gigantic coffin.

Of course there'll be endless theories about A330 systems, speculations on Boeing x Airbus, if this, if that etc...
And of course BEA, Air France, Airbus and ultimately the government of France will, each one at their convenience, try to save their own a....s.

Yep, this is the reaction to failed software - add more features that will ultimately fail.

The point is, if IAS goes south, you put the thrust at 80% and keep the nose at 3 degrees and then fly until you have visual reference and can sort it out. The last things needed are more and more complex layers of warez.

I share this view : see my first post at http://www.pprune.org/tech-log/45283...ml#post6480478

Let's assume that there are better solutions than adding software on airliners. What is the best solution for unmanned flights, military drones ?

From post #290 on 28 May 11 .... There were no replies to the above post so let the question be posed in a different form:

The iconic book 'Handling The Big Jets' by D P Davies was published in 1967 and revised in the 1977 edition. It has several pages of useful info and charts on pages 115 - 128 under the paragraph headed 'The Super Stall'.

Moreover, on page 122 there is an excellent diagram showing the 'lack of relationship between attitude and incidence'.

The recent BEA report 2 recorded the trimmable horizontal stabilizer (THS) at a 13 degrees nose-up value. Therefore the leading edge of the THS (depending on where measurements are taken) will be at a negative below horizontal datum angle of 13º).

Surely this huge displacement of 13º would be shown on the centre console manual trim wheels?

The trim wheels are visible to all 3 pilots on the flight deck. Also a true 13º is likely to have a much expanded arc on the trim wheel of perhaps double the true arc value to visually indicate this extreme displacement.

Is it Speed Over the Ground, or Velocity?
 

cogsim:What speed does a skydiver's GPS read? It subtracts where you were from where you are to come up with Speed, so probably reads zero.

The Inertial Reference Units in expensive aircraft integrate accelerations in 3 dimensions to calculate Velocity. It's been a long time since I've been intimate with inertials, but seems to me the ground speed reported by BEA was in reality Vertical Velocity.

IOW, the plane dropped like a skydiver.

Good catch, cogsim.

Report contents
 

"They are under no obligation to report
anything until the investigation is complete, but the latest report looks
as significant in terms of what it leaves out, as what's included."

The BEA published facts to put an end to random speculations based on undocumented "leaks". It has no intent to release more raw data to self appointed "analysts".

Let's wait until end of June.

Keep in mind, also, that certification stalls start with a trim speed a little above the stall. I have no idea what THS setting would have been the target range during certification but I would opine that it certainly wasn't near full up .. this may have had adverse implications on this occasion.

Further we don't have much of a story relating to just what the guys up front were actually looking at ?

the poor guys failed to recognize ... (#548)

I don't really think that we have anywhere near enough information to suggest other than that your postulated circumstance may be one of a number of possible scenarios on this occasion ?

Time will tell what the CVR may have revealed to the BEA folk but I will be very surprised if there is any panic on the flightdeck until, perhaps, the last few seconds. It has been my observation that experienced flightcrew tend to hang in there in spite of what eventually becomes an obvious pending outcome.

We are talking a reasonable level of experience here, not ab initio student pilots with only a few hours under their belts ...

This is implicitly very revealing of the software mentality - abstracting away the real world until all that's left is "flight", even though the missions and envelopes and hardware are completely different - as if there were just some abstract FlightStimulation 1.0 that could cover everything.

Well said:ok:

However if after establishing 80% and 3 NU the descent rate remains virtually straight down, you need some serious nose down to get out of the stall (said from my armchair after several minutes of reflection).

While Attitude + Power = Performance holds true in stable flight, once in an upset you need recovery actions.

AF SOPs & stall, autotrim, situation awareness
 

Hi there
About the reasons why the PF initially pitched up the AC with a high thrust index: could it simply be the implementation of "manoeuvre d'urgence" in cruise phase ? (see the AF C/L "unreliable IAS / ADR check proc", the "manoeuvre d'urgence" is page 121 of http://www.bea.aero/docspa/2009/f-cp...cp090601e1.pdf)
But this "manoeuvre d'urgence" is CLB/5°... not TOGA/16°.
Will we know the procedures that were implemeted and the way they were through the CVR ?
Is the nearly saturated THS nose up angle of 13° a consequence of the autotrim and of the (integrated/lagged) repeated nose up orders ?
situation awareness:
- 13° THS nose up angle: were the pilots informed of this ? If so, a manual trimming back to lower angles would have been their only hope then ? (related SOP ?)
- altitude/vertical speed monitoring: the 1st response to the 1st stall alarms was to pitch up/climb (manoeuvre d'urgence ?), then pitch down orders reduced the VS and stabilized the altitude around FL370 (waiting for the CPT). Latter, the CVR shows that crew was aware that the AC was closing FL100, but no early mention (in the last BEA release) of a rapid descent rate (VS).
- attitude/thrust monitoring: the pitch & thrust procedure (AP/ATHR OFF) or the "manoeuvre d'urgence" are about setting these two fundamental parameters (even on CLB/5°), and the crew tried to compensate for the roll excursions, so the crew was presumably monitoring the artificial horizon ? Though the pitch angle reached 16° at FL380, and presumably remained high on the artificial horizon (one of the reliable parameters).
- stall alarms & pitching orders: at one point (CDB was back), pitch down orders were applied with a reduced thrust, and the AoA was reducing... but it restored the validity of the airspeeds and reactivated the stall alarms: a few contributors suggested that this might have been a highly misleading factor (among many others !) urging the crew to abord these nose down orders. But nothing is said by the BEA about the following pitching orders. The BEA does not yet tell whether the word "décrochage" (stall) was heard in the cockpit (CVR).

Flight Control Laws
 

With regard tot the control laws:

Both in normal and alternate law1 and 2, both elevator and THS are programmed to produce a certain G value. This would be 1G when the side-stick is in neutral. So when there is aft side-stick, both elevator and THS try to deliver more than 1G.

Only in direct law the THS is controlled manually through the trim wheels.

The clue of the THS position would be the scale next to the trim-wheel, but this is used only prior flight. In fact, the THS is not in the mind of an Airbus pilot during flight.

I absolutely don't know what I would have done in that situation, because my brain would be in overload and also blurred by all the natural drugs in my blood....

I suspect there will be increased focus worldwide on the training of 'loss of control', 'unreliable airspeed' and use of THS.

(A330 Cp/TRI/TRE)

It's very possible that my post #546 is as crazy as the reaction suggests. But on re-reading it, it looks like I was suggesting the replacement of pitot tubes with software. That seems completely nuts, even to me. I had in mind software that could provide a reasonable airspeed reference during a brief period in which the pitot tubes became unreliable.

Hyperveloce

Very welcome post. Well framed, the challenge to the PF (PNF).

- 13° THS nose up angle: were the pilots informed of this ? If so, a manual trimming back to lower angles would have been their only hope then ? (related SOP ?) This is the salient concern? With a heavy tail and that large slab forcing down the aft hull, it is disturbing to consider the obstacles to regaining level flight.


- altitude/vertical speed monitoring: the 1st response to the 1st stall alarms was to pitch up/climb (manoeuvre d'urgence ?), then pitch down orders reduced the VS and stabilized the altitude around FL370 (waiting for the CPT). Latter, the CVR shows that crew was aware that the AC was closing FL100, but no early mention (in the last BEA release) of a rapid descent rate (VS). I think the first two warnings of Stall were transient and not perceived as reliable, after all, the a/c had 0.80-0.82 M, and had response (Pull, Roll Left)? This also occurred prior to loss of speeds reads.

At the top of climb, an AoA of 4 degrees was established, consider this may have been the best obtainable (PF: "Why?"). In arresting the climb, the a/c may have already begun its Stall, with 13 degrees NU (THS), did the crew realize this? 4 degrees AoA, but a Pitch of something much greater? Was sufficient energy available to climb in less than aerodynamic fashion? If the Pilot, absent complete cueing, was lulled into thinking his airframe was behaving normally, the sudden loss of positive g would be alarming, and he may have reduced power to drop the nose, thinking it was the engines maintaining an improper AoA? With full Trim Tanks and a THS at near full NU, did the door slam shut? Can we eliminate a cg moving aft due to loading problems?

- 11.5mb - please - anyone produce an English extract for us?

I again see "16 degrees of pitch" mentioned at FL380. Where is this published? I see only increasing through 10 in the climb. People again confusing pitch and AoA I fear. We do not know the pitch attitude at FL380. Garbage in = garbage out, as they say.

This thread is rapidly becoming the third farce in the history of threads on this accident. The BEA have released so little information it is impossible to understand what happened. Where is the CVR call of "what are you doing" by PNF as the pitch rises through 10 degrees and a heavy a/c climbs at 7000fpm at FL360 - from optimum altitude towards ceiling? Unreal. So much more must have been happening.