HazelNuts39

Machinbird,
I'd be interested in the definition of AoA at 0 airspeed and in the accuracy of the value you observed. Did the maneuver you were performing require accurate knowledge of AoA?

Lyman

You guys should agree on the difference between Indicated and Actual.

Save some time. Once STALLED, any recovery will erm, recover.

Believing something that is not true ("STALL", "NOT STALL", ) is at the heart of this entire debate, and the crew were recipients of the actuals, not the debatables.

Captain heard (briefly) STALLSTALL, then it ceased. The a/c was flying substantially faster than 60 knots. Having heard it, then its cessation, the Captain was done entertaining a STALL, at least due "WARNING".

Machinbird

As you no doubt surmised, unless you are flying a thrust vectored overpowered aircraft such as an F-22, the transit of 0 airspeed is just that, transitory. You pull the nose up to vertical and let the speed bleed off until there isn't any. The indication generally stays close to 0 AOA unless you develop a pitch rate as you lose control authority. Then, as the aircraft backs down, the indicator flips to one of its limits and the aircraft then flips over briskly to point its nose down (with some oscillation) and the AOA stabilizes back at usable values. If you are wise, you will wait until you have some g available before attempting any control inputs.

None of this has any applicability to transport aircraft other than the deviation from correct AOA indications is brief and of no practical concern to the pilot. One would hope that a flight control system that experiences this type maneuver would also avoid making control inputs during the brief period that control authority is minimal. AOA at 0 airspeed is, of course, undefined.

GerardC

Initially posted by BLCL...modern jet flying.

You are spot on BLCL.

What about :
If you read BEA's report, at 02:06:50 they noticed that SAT was -42°C, thence, anti-ice will NOT be needed.
"C'est toujours ça de pris" means they are satisfied not being forced to use anti-ice.
Pilots always begin with swiching nacelle anti-ice ON and then, if needed, they switch wing anti-ice ON.

Nacelle anti-ice were not switched ON until 02:10:03.
BEA does not mention wing anti-ice being switched ON at that time.


Once again, if you read BEA's report, "The copilot in the left seat moved the weather radar gain control to maximum, after noticing that he was in calibrated mode."
There is nothing "incorrect" using the radar in Calibrated mode.

Etc, etc.....

ChristiaanJ

Nope....
Don't rely on those approximate translations of colloquial French.
In this case, the basic notion is : "we might as well turn it on".

GerardC

Non, c'est une interprétation/compréhension incorrecte. "C'est toujours ça de pris" veut dire : c'est une bonne chose de ne pas avoir à les utiliser (on consommera moins de pétrole).

I stick to my guns. They were happy to dispense with NAI/WAI (less fuel burn).
BEA french version page 91 : "Moins quarante deux on utilisera pas les anti ice, c’est toujours ça de pris"

lucaturin

Correct: "toujours ça de pris" means something like "one in the bag" and indicates a saving of some kind [I'm a native French speaker, FWIW].

captplaystation

Excuse me for bursting in, speaking English ( I am joking ! ) but, if the CVR transcript presented in the link from GlueBall is correct (is it ? & if so how did the author of the associated book get his hands on it ? ) my heart bleeds.

Reading it and trying to imagine it in real-time , in a noisy cockpit , being buffeted by convective activity & no doubt stall induced aerodynamic buffeting, whilst these 3 guys sat there descending @ 10,000fpm without any real clue of what is going on is depressing/heartbreaking/shocking in equal measure.

One wonders what, if anything, they realised in the cabin, or possibly (I hope) they just thought it was "a bit rough" until the impact.

I find this one of the most distressing things I have ever read in an accident report, can't (or at least don't want to ) imagine what they were feeling as they realised around 10,000ft or so just how deep was the merde they were engulfed by.

Nightmare stuff

A310bcal

Having read the transcript above about a week ago, my immediate reaction to this very sad accident was that it was so avoidable...... as always with the benefit of hindsight of course!
My first thought was why should a pilot pull back so hard on the sidestick, putting the Airbus into a zoom climb and stall..... it was as if he became "frozen " onto the control.....I experienced a newish student doing this to me in a Chipmunk more than 30 years ago during a spinning detail, but here we have a relatively mature and qualified co-pilot. But had the St Elmos fire and smell of "burning" unnerved him so much, perhaps having had the Captain leave him with a younger less experienced colleague?.......but my main question which puzzles me is "why did the Captain choose such an inappropriate time to leave the flight deck" ?
I have encountered the ITCZ many times over Africa, and also on the route up from South America into Europe, and no one can underestimate the power of nature in this region. As a co-pilot, the Captains in the two Airlines I was privileged to fly for, would choose their rest period at a time that would ensure they were in the cockpit for the period of time when one might expect to be crossing through the ITCZ. Later when I had my command, I too ensured I was in the LHS whilst we negotiated a safe ( but not always smooth ) passage through that area of the World. It surprises me therefore, that the AF Captain chose his break at a time when I think most Captains would want to be at the sharp end doing what they are paid for...... ensuring a safe flight. I wonder if I am being extremely naive about this..... what would you guys do I wonder?
I also wonder why the Captain was so long in returning to the flight deck...... the aircrafts pitch up and noise from the engines must surely have alerted him to the fact that something was not right, and then when he had returned to the flight deck, assuming it was possible, why did he not get straight into his seat to try and arrest their situation..... perhaps then the young co-pilot might just have relinquished control to him, as it would appear from the transcript that he was frozen onto that sidestick for most of the downward flight.
Whilst it is easy to blame Airbus technology for what happened, I'm sad to say that the chain of events could so easily have been broken in those first few minutes, had the Captain been present on the flight deck. For sure , all long range flying has to cater for crew rest, but IMHO the allocation and choice of break times was rather inappropriate, and eventually fatal.
Very very sad !!!!

CONF iture

Forget about any IAS value.
If one of the AoA vanes indicates a stall value : WARN
... except if weight on wheel.

I am the captain on AF447, I enter the cockpit, the right seater maintains the yoke to his stomach using both hands and the STALL WARNING continuously warns : I have here very serious indications what the problem is, don't you think ?

Tay Cough

Yes. The right seater is clearly in a Boeing.

Seriously, the reaction to a stall warning in an Airbus is exactly the same as in any other aircraft. Reduce the angle of attack.

AlphaZuluRomeo

Sir, thanks for the link. Just bought the french edition of the book.

If you're the author, as suggests your pseudonym:
The overall analysis seems OK, complete, wide & thorough.

On the down side, when going to details, I found myself puzzled by several imprecisions, confusions or errors.
I pretend to be knowledgeable about the AF447 events, and think I spoted those "issues" because of that.
On the other hand, the "casual" reader won't be able to spot those points... That's sad, because they add much confusion IMO, on an interesting & valuable book.

Will finish my reading & will post a more precise review later.

NB: I'm aware that some errors/confusions may be translation issues, too.

AlphaZuluRomeo

@ GerardC & ChristiaanJ: Your "disagreement" made me discover (another) difference between:
- the CVR transcript from the BEA 3rd interim report
and
- the CVR transcript from Otelli's book (which is the one quoted in the Popular Mechanics article)

GerardC => your interpretation is correct based on the BEA transcript
ChristiaanJ => your interpretation is correct based on Otelli's / PM transcript

Sometimes, those two transcripts say the contrary one to another. It's the case here, with :
(BEA) "Moins quarante deux, on utilisera pas les anti-ice c’est toujours ça de pris"
(Otelli) "Va pour les anti-ice. C'est toujours ça de pris."

@ captplaystation:
The transcript in the Popular Mechanics article is an excerpt of the so-called "full" transcript in Otelli's book "Erreurs de pilotage N°5" (published in french only).
I commented here on Otelli's (& PM) book, the baseline being this transcript appears based on a draft (initial listening of the CVR?). Otelli got his hands on it via a leak, obviously.
I think the transcript published by the BEA in its interim report is more accurate (and less complete, the BEA having published 'only' "excerpts from the CVR transcript").
In the example above, the fact that no anti-ice was selected ON (per FDR data) following this sentence by the PF means indeed the BEA is right.

captplaystation

A310bcal, totally with you there, I certainly WOULDN'T have got any rest anyhow if I had left the cockpit just before the most "interesting" phase of the flight. Inexplicable indeed to bugger off at that particular moment. . . .

Alpha Zulu Romeo, sorry, wasn't fixating on the exact words, I don't doubt the basic validity (the end result seems to support it ) the exact translation is for someone else, I was merely curious how the "author" had access to this CVR data.

Anyhow, finally, a sad indicetment, both of human fallibility, & Airbus technology IMHO.

FlyingtheLine

Shy Talk - you are right. 100%

Machinbird

Per the BEA 3rd report, commencing at 2h 10min 27, there were a series of criticisms from the PNF that are altitude related. At 2h 10min 36 there was a comment that from the context would have clearly stated how badly PF had fouled up "You’re at"......
?altitude?, but PNF cut it short and told PF very simply to "Go back down."

If I would have been in that cockpit, I think I would have told the other guy how far he was off the intended altitude and I was looking for this type of communication in the record.

It appears to me that PNF was trying to avoid stressing a badly rattled PF any more than necessary and was keeping communication "baby simple."

It would be difficult to start the ECAM drill with such a badly rattled guy trying to fly the aircraft.

bubbers44

Don't you think when the FO has lost control of the aircraft you could take over and recover from this stupid mistake of the PF? Why let everybody die because you didn't do anything to help the situation? This is why we can't let inexperienced pilots fly airliners. Sometimes the autopilot fails and you need someone behind the controls that has a clue how to hand fly it. They didn't.

Machinbird

Yep, that is exactly what I would do. Warn the guy twice what he needs to fix, if time permits, then if he can't control it, tell him I have it and what I want him to do.
And if he doesn't keep his paws off of the controls then, its crash axe time.

It is obvious that PNF lost track of the energy picture too and was not confident of his own abilities. A lack of courage it seems.

Dream Land

Bubbers has it right, probably been covered before, but didn't I read that other aircraft on this route deviated, and this cruise team flew directly into the Wx because they didn't have the radar set up properly?

Is there any other proof needed that a real captain needs to be sitting in the left seat?

GerardC

Initially posted by AZR : +1

If you do not cross check CVR sentences with FDR recorded actions, the point can be missed by a wide margin.