AF 447 Thread No. 6
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ALTERNATEs
@RetiredF4:
ALT1:
Pitch attitude (Θ) protection lost.
Hi Speed and Stall speed are alternate.
ALT1A:
As ALT1 but Stall protection is lost.
ALT2:
As ALT1 but lateral normal law is lost and replaced by
lateral alternate (Roll = DIRECT; Yaw = Alternate)
ALT2A:
As ALT2 (Stall protection is lost)
ALT2B:
Pitch attitude (Θ) protection lost.
Hi Speed and Stall protection lost.
Bank angle protection lost
---
Source: ?? my personal notes.
BEA in its report mentiones the ALT2B law as present, but does not describe in detail, what kind of protections had been lost and which ones still had been active. In my references i couldn´t find what the letter "B" in Alt2B stands for.
ALT1:
Pitch attitude (Θ) protection lost.
Hi Speed and Stall speed are alternate.
ALT1A:
As ALT1 but Stall protection is lost.
ALT2:
As ALT1 but lateral normal law is lost and replaced by
lateral alternate (Roll = DIRECT; Yaw = Alternate)
ALT2A:
As ALT2 (Stall protection is lost)
ALT2B:
Pitch attitude (Θ) protection lost.
Hi Speed and Stall protection lost.
Bank angle protection lost
---
Source: ?? my personal notes.
Last edited by A33Zab; 20th Aug 2011 at 17:11.
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Thank you for the info, couldn´t find it myself.
Than can we assume that it was active before AP dropped out, as turbulence was expected?
How would that influence the FDR traces before and after AP dropout and would the AC behaviour be more rough thereafter, reflecting in the traces?
Than can we assume that it was active before AP dropped out, as turbulence was expected?
How would that influence the FDR traces before and after AP dropout and would the AC behaviour be more rough thereafter, reflecting in the traces?
Recently I went and re-read some sections of the BEA Report again, and I found the rereading of the mid section graphs and analysis quite useful in light of all the information I've got and reflected onto after/since the first reading.
Last edited by airtren; 20th Aug 2011 at 17:05.
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Hello mm43,
Thanks for your clarifications. I understand your reference to the Stall Warning better. The Stall Warning was active later during the event, there is at least one additional reference to it at page 14 (English text), besides, the one I've mentioned in the CVR transcript (French translation).
There is another Airbus Stall recovery reference, which you may find interesting. Again, possible mistakes, but excellent airmanship, and talent to get the plane out of the Stall:
Interflug A310 Stall 1991 Sheremetyevo
I think I understand your interpretation better.
Thanks for your clarifications. I understand your reference to the Stall Warning better. The Stall Warning was active later during the event, there is at least one additional reference to it at page 14 (English text), besides, the one I've mentioned in the CVR transcript (French translation).
There is another Airbus Stall recovery reference, which you may find interesting. Again, possible mistakes, but excellent airmanship, and talent to get the plane out of the Stall:
Interflug A310 Stall 1991 Sheremetyevo
I think I understand your interpretation better.
At no time was the SS placed in the neutral position which would have enabled the autotrim function to maintain 1g, so effectively that function was over-ridden by the PF. Hence my reason for saying that 'autotrim' had nothing to do with it.
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AlphaZuluRomeo, thanks for the clarification, it's very helpful.
If I understand correctly, you're suggesting "limiting any further NU move" of the THS at Stall in Alternate.
I like it - it's a rephrasing or refinement of part #1 of the earlier suggestion, with its implicit parts:
If I understand correctly - please correct me if I my understanding is wrong - there is an implicit relying on the fact that this would happen after a transition from Normal at cruise at high altitude, to Alternate, so that the THS would not be at max NU, and the Stall Warning would start well before the THS would/could get there.... I like it!.... Cruise at high altitude is an important condition...
Edit: The THS move ND is left to the initiative of the pilot, continueing to function as defined, auto trim consequence of strong and persistent Elevators ND, or manual trim THS ND.
airtren
If I understand correctly, you're suggesting "limiting any further NU move" of the THS at Stall in Alternate.
I like it - it's a rephrasing or refinement of part #1 of the earlier suggestion, with its implicit parts:
If I understand correctly - please correct me if I my understanding is wrong - there is an implicit relying on the fact that this would happen after a transition from Normal at cruise at high altitude, to Alternate, so that the THS would not be at max NU, and the Stall Warning would start well before the THS would/could get there.... I like it!.... Cruise at high altitude is an important condition...
Edit: The THS move ND is left to the initiative of the pilot, continueing to function as defined, auto trim consequence of strong and persistent Elevators ND, or manual trim THS ND.
airtren
@ airtren : You're welcome, Sir.
Please note the THS logic in normal law (from the FCOM):
NB : 2° ND is max position ND of the THS.
So basically, the idea I proposed is already the way Airbus'logic deals with the THS in Normal law. Let's do the same in Alternate law.
Please note the THS logic in normal law (from the FCOM):
NB : 2° ND is max position ND of the THS.
So basically, the idea I proposed is already the way Airbus'logic deals with the THS in Normal law. Let's do the same in Alternate law.
Last edited by airtren; 22nd Aug 2011 at 12:52.
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AZR RE: "Unprotected". In STALL (Alpha), was my meaning. 'G' protection is assumed. The THS was inhibited from TRIM whilst the 'g' was out:
-0.75/+1.25. Is this not why the THS rermained at ~3 degrees on the way up? (zoom climb). Then, after 'g' re-entered -.75><1.25, the THS started to chase 'G' from inside the fence? Concurrent with STALL, of course, and that is the rub?
So, may we see it this way: that THS was dormant whilst a/c was 'maneuvering' (climbing, "bucking"), and it travelled NOSEUP MAX not only to follow elevator, but to prevent 'g' 'negative'? Perhaps a fine point, 'WHY' the THS did what it did, but there remain those two possibilities?
I think it is important to consider that though the pilot appears to be in Thrall with PIO, there is a PIO that can occur in reverse. Specifically, PIO induced 'Turbulence'? Seen it, done it.
-0.75/+1.25. Is this not why the THS rermained at ~3 degrees on the way up? (zoom climb). Then, after 'g' re-entered -.75><1.25, the THS started to chase 'G' from inside the fence? Concurrent with STALL, of course, and that is the rub?
So, may we see it this way: that THS was dormant whilst a/c was 'maneuvering' (climbing, "bucking"), and it travelled NOSEUP MAX not only to follow elevator, but to prevent 'g' 'negative'? Perhaps a fine point, 'WHY' the THS did what it did, but there remain those two possibilities?
I think it is important to consider that though the pilot appears to be in Thrall with PIO, there is a PIO that can occur in reverse. Specifically, PIO induced 'Turbulence'? Seen it, done it.
Originally Posted by rudderrudderrat
Why don't Boeing pilot's pull their wings off?
Originally Posted by rudderruderrat
What makes you think it is now properly trained?
Originally Posted by airtren
I was also looking for your own words, and your own logic
Originally Posted by Lyman
So, may we see it this way: that THS was dormant whilst a/c was 'maneuvering' (climbing, "bucking"), and it travelled NOSEUP MAX not only to follow elevator, but to prevent 'g' 'negative'?
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MAYDAY Season 11 where available.
Episode 2: The Plane That Flew Too High
West Caribbean Airways Flight #708
McDonnell Douglas MD-82
Same thing one exception, copilot knew they were stalling.
Episode 2: The Plane That Flew Too High
West Caribbean Airways Flight #708
McDonnell Douglas MD-82
Same thing one exception, copilot knew they were stalling.
Last edited by VGCM66; 20th Aug 2011 at 16:58.
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Re Alternate....Halfway serious question.... :
Could you have recited that list without your notes (AND clearly visualised or 'conceptualised' each particular case) in a car going down-hill with the power steering having given up, and a broken brake line - while pumping the brakes ?
In view of your valuable contributions, let me assure you: I'm NOT trying to be funny.
But as an engineer (not a pilot), I see this as unnecessary 'mode complexity'.
Could you have recited that list without your notes (AND clearly visualised or 'conceptualised' each particular case) in a car going down-hill with the power steering having given up, and a broken brake line - while pumping the brakes ?
In view of your valuable contributions, let me assure you: I'm NOT trying to be funny.
But as an engineer (not a pilot), I see this as unnecessary 'mode complexity'.
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To RetiredF4
Please,
>Never start any e-mail with a plead, it shows what/who you really are right from the onset and it is not complementary as in not flattering believe me.
if you are new to this thread ...
>Yes, new since June first, 2009.
and want to contribute
>Not contributing just adding, hopefully and maybe another point of view.
something useful out of...
>Another opinion is always useful but I guess not in your world as some sort of supreme self-appointed commander in chief of the truth. Yours and only your truth that is.
your expierience as an engineer ...
>I am guilty of this. Twice. You?
or any other profession you are familiar with,
>Again guilty: Automatic Controls Systems and Applications. You?
it would be appropriate to read the nearly 1.000 pages filled about this flight.
>And again, I had. The very best and the very worst too. That is because PPRuNe is a free open for discussions Forum and not your Private Club playground where you have self appointed yourself as critic of posts and anything else you do not like. Not a private club of any kind and specially not yours.
That would tune you in the loop of the discussion.
>I am but it looks you are not.
There had been failures, there had been mistakes, and there are things which can be improved to reduce the probability of similar accidents.
>You can count on humans more. They'll do it again somehow and somewhere and blame something else for it at first. Ultimately, it always falls on us again.
The big question to all these matters is "why"?
>Wrong again. It is "HOW? as in: How can we stop this from ever happening again?
Your ranting does not contribute to this task.
>You only showed your supreme ignorance of a variety of different definitions as well as subjects.
> A330 will not be redesigned and humans in cockpits will be modified accordingly to stop future tragic events like flight AF447. We hope.
VGCM66
Please,
if you are new to this thread and want to contribute something useful out of your expierience as an engineer or any other profession you are familiar with, it would be appropriate to read the nearly 1.000 pages filled about this flight.
That would tune you in the loop of the discussion.
There had been failures, there had been mistakes, and there are things which can be improved to reduce the probability of similar accidents.
The big question to all these matters is "why"?
Your ranting does not contribute to this task.
Please,
if you are new to this thread and want to contribute something useful out of your expierience as an engineer or any other profession you are familiar with, it would be appropriate to read the nearly 1.000 pages filled about this flight.
That would tune you in the loop of the discussion.
There had been failures, there had been mistakes, and there are things which can be improved to reduce the probability of similar accidents.
The big question to all these matters is "why"?
Your ranting does not contribute to this task.
>Never start any e-mail with a plead, it shows what/who you really are right from the onset and it is not complementary as in not flattering believe me.
if you are new to this thread ...
>Yes, new since June first, 2009.
and want to contribute
>Not contributing just adding, hopefully and maybe another point of view.
something useful out of...
>Another opinion is always useful but I guess not in your world as some sort of supreme self-appointed commander in chief of the truth. Yours and only your truth that is.
your expierience as an engineer ...
>I am guilty of this. Twice. You?
or any other profession you are familiar with,
>Again guilty: Automatic Controls Systems and Applications. You?
it would be appropriate to read the nearly 1.000 pages filled about this flight.
>And again, I had. The very best and the very worst too. That is because PPRuNe is a free open for discussions Forum and not your Private Club playground where you have self appointed yourself as critic of posts and anything else you do not like. Not a private club of any kind and specially not yours.
That would tune you in the loop of the discussion.
>I am but it looks you are not.
There had been failures, there had been mistakes, and there are things which can be improved to reduce the probability of similar accidents.
>You can count on humans more. They'll do it again somehow and somewhere and blame something else for it at first. Ultimately, it always falls on us again.
The big question to all these matters is "why"?
>Wrong again. It is "HOW? as in: How can we stop this from ever happening again?
Your ranting does not contribute to this task.
>You only showed your supreme ignorance of a variety of different definitions as well as subjects.
> A330 will not be redesigned and humans in cockpits will be modified accordingly to stop future tragic events like flight AF447. We hope.
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@ChristiaanJ:
Hi CJ,
Absolutely NOT and also NOT of any use,
it was an answer to RetiredF4s question about the 'B' in ALT2B and I mentioned
the other alternate modes and source in advance of the expected next questions.
I agree.........set and forget.
BTW, considering my car, it wouldn't even get up-hill.
Halfway serious question.... :
Could you have recited that list without your notes (AND clearly visualised or 'conceptualised' each particular case) in a car going down-hill with the power steering having given up, and a broken brake line - while pumping the brakes ?
Could you have recited that list without your notes (AND clearly visualised or 'conceptualised' each particular case) in a car going down-hill with the power steering having given up, and a broken brake line - while pumping the brakes ?
it was an answer to RetiredF4s question about the 'B' in ALT2B and I mentioned
the other alternate modes and source in advance of the expected next questions.
I agree.........set and forget.
BTW, considering my car, it wouldn't even get up-hill.
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Originally Posted by Clandestino
Don't you adapt your inputs to achieve desired attitude, no matter what control law are you in?
Clandestino, if you start feeling Gs do you still pull harder or you just relax … ?
If you set and hold 5° and set climb power, the aeroplane will climb, after a while power available goes down with altitude, EAS goes slowly down, AoA goes gently up and aeroplane levels off when AoA reaches five degrees minus wing incidence angle.
What about a more common sense 2.5 deg pitch ?
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Originally Posted by CONF iture
Except that 5 degrees of AoA on AF447 and stall warning is already warning, stall itself is just about.
Last edited by HazelNuts39; 20th Aug 2011 at 22:10.
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So I considered just allowing a slag off of my opinion, but I think it a good question, and will pose it once more.
Per the post by airtren of the THS and Elevator traces, I notice a dormant THS, positioned at 3 degrees virtually the entire time of the climb. It then travels to 13.6 degrees Nose Up at a very consistent rate at and during the STALL WARN.
STALL Protection is lost in ALTERNATE LAW, but 'g' protection remains. The elevators work via the FCS, and respond to load, or g sense.
So Pitch is not DIRECT, and it is independent of an "active" (variable) Stick. No excessive elevator deflection to be expected. The climb shows a response to NU input, again, without TRIMMING, which is ACTIVE in this LAW.
Why then, no "compensation" for the elevator position? The stick is held back sufficiently to command autotrim, but none shows.
Why? Because the THS, its Autotrim function, is inhibited in the region above 1.25 g, and below .75 g. The g traces show that the g is consistently outside the normal Autotrim range, so no mystery. Then, as the a/c climbs to its apogee, and g re enters the range in which Autotrim is ACTIVE, the THS migrates at an even rate to its NOSEUP stop. At no time do I see a variable rate from the THS, it lumbers along from 3 degrees to the stop, seemingly independent of a reason to do so in such a manner. This all seems inexplicable to me, what is the relationship between elevator and THS in this trajectory?
That is the best wording I can come up with. I started what seemed like a fruitful exchange with MR. clandestino, but found out my question lacked aerodynamic validity, and seriously challenged basic Physics. That's it, no answer, just slag.
Oh, except for a picture of a fifty year old design, and a rejoinder that Mr. Davies knew more than he.
Fair. I think mine is a valid question, and not a steaming pile, as has been inferred. If a pile, please ignore.
Per the post by airtren of the THS and Elevator traces, I notice a dormant THS, positioned at 3 degrees virtually the entire time of the climb. It then travels to 13.6 degrees Nose Up at a very consistent rate at and during the STALL WARN.
STALL Protection is lost in ALTERNATE LAW, but 'g' protection remains. The elevators work via the FCS, and respond to load, or g sense.
So Pitch is not DIRECT, and it is independent of an "active" (variable) Stick. No excessive elevator deflection to be expected. The climb shows a response to NU input, again, without TRIMMING, which is ACTIVE in this LAW.
Why then, no "compensation" for the elevator position? The stick is held back sufficiently to command autotrim, but none shows.
Why? Because the THS, its Autotrim function, is inhibited in the region above 1.25 g, and below .75 g. The g traces show that the g is consistently outside the normal Autotrim range, so no mystery. Then, as the a/c climbs to its apogee, and g re enters the range in which Autotrim is ACTIVE, the THS migrates at an even rate to its NOSEUP stop. At no time do I see a variable rate from the THS, it lumbers along from 3 degrees to the stop, seemingly independent of a reason to do so in such a manner. This all seems inexplicable to me, what is the relationship between elevator and THS in this trajectory?
That is the best wording I can come up with. I started what seemed like a fruitful exchange with MR. clandestino, but found out my question lacked aerodynamic validity, and seriously challenged basic Physics. That's it, no answer, just slag.
Oh, except for a picture of a fifty year old design, and a rejoinder that Mr. Davies knew more than he.
Fair. I think mine is a valid question, and not a steaming pile, as has been inferred. If a pile, please ignore.
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Air France 447 - AFR447 - A detailed meteorological analysis - Comments from pilots and other aviation professionals
in case you haven't seen it.
in case you haven't seen it.
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Hi Lyman,
As the speed washed off, the nose of the aircraft would want to drop naturally. The FBW computers are programmed to maintain attitude, so more nose up from the elevator is required. The stab was autotrimmed to reduce the amount of elevator deflection required.
what is the relationship between elevator and THS in this trajectory?
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@ airtren (re: #223)
Yes, you understood perfectly what I suggested
"implicit relying"? I wouldn't have phrased it like that, but anyway: It's a fact that the proposed solution will be of no use in a "Perpignan-like" case (reversion to direct law), nor if we take the hypothesis of "just" a reversion to alternate after the THS is already max NU.
But Perpignan was a specific case, with AoA measurement errors: one can't elaborate on that, as (reliable) AoA is required for stall warning.
As for you last §, I'm sorry I don't get your point? What do you mean?
"The limiting, which you look at, if I understand correctly, as a temporary excursion of THS control in DirectLaw could be made Stall Warning dependent, instead of a fixed time interval? Pre-defined time intervals, don't always (actually I should say they rarely) respond well to needs in very dynamic situations."
---------
@ Lyman (re: #224)
I understood "unprotected" as "not a single protection". And, as you seemed astonished that rudder was limited (NB: that's for structural limits reasons) but not the pitch, I replyied with the fact that the pitch is also limited (in g, not regarding stall/AoA, on that we agree), due to structural limits reasons.
Now, regarding the stall/AoA protection: If the aircraft could have delivered it, it would have. ALTERNATE LAW (PROT LOST) says it well, doesn't it?
Yes, you understood perfectly what I suggested
"implicit relying"? I wouldn't have phrased it like that, but anyway: It's a fact that the proposed solution will be of no use in a "Perpignan-like" case (reversion to direct law), nor if we take the hypothesis of "just" a reversion to alternate after the THS is already max NU.
But Perpignan was a specific case, with AoA measurement errors: one can't elaborate on that, as (reliable) AoA is required for stall warning.
As for you last §, I'm sorry I don't get your point? What do you mean?
"The limiting, which you look at, if I understand correctly, as a temporary excursion of THS control in DirectLaw could be made Stall Warning dependent, instead of a fixed time interval? Pre-defined time intervals, don't always (actually I should say they rarely) respond well to needs in very dynamic situations."
---------
@ Lyman (re: #224)
I understood "unprotected" as "not a single protection". And, as you seemed astonished that rudder was limited (NB: that's for structural limits reasons) but not the pitch, I replyied with the fact that the pitch is also limited (in g, not regarding stall/AoA, on that we agree), due to structural limits reasons.
Now, regarding the stall/AoA protection: If the aircraft could have delivered it, it would have. ALTERNATE LAW (PROT LOST) says it well, doesn't it?
Like others, I suspect, I have been struggling to understand the PF’s reaction(s) after he was handed control of the aircraft when the AP dropped out.
I am not a pilot but my understanding is that the PF took action(s) opposite to or at variance with those normally expected in such a situation.
The apparent lack of meaningful/productive communication between PF and PNF – not going through SOPs, etc – and the frantic requests for the Captain to return suggests to me that in essence they had no idea what was going on or where to start to resolve things.
Accordingly the PF may have decided that everything he was seeing and hearing was incorrect leading to him shutting it all out as he sought to aviate. Using his ‘gut feeling’ his default position became an effort to secure altitude and power - to give a safe “breathing space” to evaluate what was in fact happening - thus explaining NU and TOGA.
I accept that PNF may have had some (growing?) understanding but he did not communicate this with the strength required or take over control apart from a very brief period before being usurped by a PF locked into a wrong belief about what was needed almost right to the very end.
As I say, I am not a pilot but wondered if the above explanation might fit with what tragically transpired…
I am not a pilot but my understanding is that the PF took action(s) opposite to or at variance with those normally expected in such a situation.
The apparent lack of meaningful/productive communication between PF and PNF – not going through SOPs, etc – and the frantic requests for the Captain to return suggests to me that in essence they had no idea what was going on or where to start to resolve things.
Accordingly the PF may have decided that everything he was seeing and hearing was incorrect leading to him shutting it all out as he sought to aviate. Using his ‘gut feeling’ his default position became an effort to secure altitude and power - to give a safe “breathing space” to evaluate what was in fact happening - thus explaining NU and TOGA.
I accept that PNF may have had some (growing?) understanding but he did not communicate this with the strength required or take over control apart from a very brief period before being usurped by a PF locked into a wrong belief about what was needed almost right to the very end.
As I say, I am not a pilot but wondered if the above explanation might fit with what tragically transpired…
upset / stall / recovery
A post in the thread causes myself to go back to the upset and stall and the
unsuccessful recognition and recovery from the stall.
Upset recovery training zip
posted on http://www.pprune.org/tech-log/41797...ml#post6652672
Although the posted reference is dated from August 2004, it is imho an excellent work. It is not the powerpoint presntation, but it consists of 185 pages of very interesting read.
But it deals with non FBW aircraft, has some references to them that those might not stall as being protected.
Actually if those informations and recomendations had been used from the crew of AF447, the outcome would have been most probably a different one.
I´ve copied some sentences for info.
Simulator versus reality
The Alpha and Beta values are depicted in Appendix 3 for a lot of aircraft, from AB the A300/A310.
In short with flaps up flight validated from 0° AOA up to 12 AOA,
Wind tunnel / analythical from -5°AOA up to 12 ° AOA
Extrapolated for simulator from -5° AOA up to 30° AOA
AF447 maneuvered well outside those limits.
Startle factor
Unloading
Cockpit environment
Flight controls
Stall aproach / Stall
Stall recovery
Stall recovery procedure for AF447 (would have worked, imho)
Pitch control
An interesting read, especially IMHO for the non-flyers on this thread. Pilots should know it anyway.
unsuccessful recognition and recovery from the stall.
Upset recovery training zip
posted on http://www.pprune.org/tech-log/41797...ml#post6652672
Although the posted reference is dated from August 2004, it is imho an excellent work. It is not the powerpoint presntation, but it consists of 185 pages of very interesting read.
But it deals with non FBW aircraft, has some references to them that those might not stall as being protected.
Actually if those informations and recomendations had been used from the crew of AF447, the outcome would have been most probably a different one.
I´ve copied some sentences for info.
Simulator versus reality
There are issues associated with differences between simulator training and aircraft recoveries. A simulator can provide the basic fundamentals for upset recovery, but some realities such as positive or negative g’s, startle factor, and environmental conditions are difficult or impossible to replicate. These limitations in simulation add a degree of complexity to recovery from an actual aircraft upset because the encounter can be significantly different from that experienced during simulator training. Therefore memory checklists or procedural responses performed in training may not be repeatable during an actual upset situation. The limitations of simulators at the edges of the flight envelope can also cause fidelity issues because the simulator recovery may or may not have the same response characteristics as the aircraft being flown. However, provided the alpha and beta limits are not exceeded, the initial otion responses and instrument indications of the simulator should replicate airplane responses.
In short with flaps up flight validated from 0° AOA up to 12 AOA,
Wind tunnel / analythical from -5°AOA up to 12 ° AOA
Extrapolated for simulator from -5° AOA up to 30° AOA
AF447 maneuvered well outside those limits.
Startle factor
It has already been stated that airplane upsets do not occur very often and that there are multiple causes for these unpredictable events. Therefore, pilots are usually surprised or startled when an upset occurs. There can be a tendency for pilots to react before analyzing what is happening or to fixate on one indication and fail to properly diagnose the situation. Proper and sufficient training is the best solution for overcoming the startle factor. The pilot must overcome the surprise and quickly shift into analysis of what the airplane is doing and then implement the proper recovery. Gain control of the airplane and then determine and eliminate the cause of the upset.
Airline pilots are normally uncomfortable with aggressively unloading the g forces on a large passenger airplane. They habitually work hard at being very smooth with the controls and keeping a positive 1-g force to ensure flight attendant and passenger comfort and safety. Therefore, they must overcome this inhibition when faced with having to quickly and sometimes aggressively unload the airplane to less than 1 g by pushing down elevator.
Pilots must anticipate a significantly different cockpit environment during less-than-1-g situations. They may be floating up against the seat belts and shoulder harnesses. It may be difficult to reach or use rudder pedals if they are not properly adjusted. Unsecured items such as flight kits, approach plates, or lunch trays may be flying around the cockpit. These are things that the pilot must be prepared for when recovering from an upset that involves forces less than 1-g flight.
Utilizing full flight control authority is not a part of routine airline flying. Pilots must be prepared to use full flight control authority if the situation warrants it. In normal conditions, flight control inputs become more effective with increased speed/ reduced angle of attack. Conversely, at speeds approaching the critical angle of attack, larger control inputs are needed for given aircraft reactions. Moreover, during certain abnormal situations (partial high lift devices, thrust reverser in flight) large or full-scale control inputs may be required. Attitude and flight path changes can be very rapid during an upset and in responding to these sorts of upset conditions, large control inputs may be necessary. It is important to guard against control reversals. There is no situation that will require rapid full-scale control deflections from one side to the other.
Pilots are routinely trained to recover from approach to stalls. The recovery usually requires an increase in thrust and a relatively small reduction in pitch attitude. Therefore, it may be counterintuitive to use greater unloading control forces or to reduce thrust when recovering from a high angle of attack, especially at lower altitudes. If the airplane is stalled while already in a nosedown attitude, the pilot must still push the nose down in order to reduce the angle of attack. Altitude cannot be maintained and should be of secondary importance.
A stall is an out-of-control condition, but it is recoverable. To recover from the stall, angle of attack must be reduced below the stalling angle—apply nosedown pitch control and maintain it until stall recovery. Under certain conditions, on airplanes with underwing-mounted engines, it may be necessary to reduce thrust to prevent the angle of attack from continuing to increase. If the airplane is stalled, it is necessary to first recover from the stalled condition before initiating upset recovery techniques.
Situation: Pitch attitude unintentionally more than
25 deg, nose high, and increasing.
Airspeed decreasing rapidly.
Ability to maneuver decreasing.
Nose-high, wings-level recovery:
◆ Recognize and confirm the situation.
◆ Disengage autopilot and autothrottle.
◆ Apply as much as full nosedown elevator.
◆ Use appropriate techniques:
• Roll to obtain a nosedown pitch rate.
• Reduce thrust (underwing-mounted engines).
◆ Complete the recovery:
• Approaching horizon, roll to wings level.
• Check airspeed, adjust thrust.
• Establish pitch attitude.
25 deg, nose high, and increasing.
Airspeed decreasing rapidly.
Ability to maneuver decreasing.
Nose-high, wings-level recovery:
◆ Recognize and confirm the situation.
◆ Disengage autopilot and autothrottle.
◆ Apply as much as full nosedown elevator.
◆ Use appropriate techniques:
• Roll to obtain a nosedown pitch rate.
• Reduce thrust (underwing-mounted engines).
◆ Complete the recovery:
• Approaching horizon, roll to wings level.
• Check airspeed, adjust thrust.
• Establish pitch attitude.
Pitch may be controlled by rolling the airplane to a bank angle that starts the nose down. The angle of bank should not normally exceed approximately 60 deg. Continuous nosedown elevator pressure will keep the wing angle of attack as low as possible, which will make the normal roll controls effective. With airspeed as low as the onset of the stick shaker, or lower, up to full deflection of the ailerons and spoilers can be used. The rolling maneuver changes the pitch rate into a turning maneuver, allowing the pitch to decrease.
