Air France Flight 447 report

[excaza]

They certainly didn't see a rookie pilot, who couldn't recognize and recover from a stall, being in command of the aircraft, while two other experienced pilots looked on ..

Yes, yes, hindsight 20/20 and all, but it just seems like a bizarre choice for redundancy.

 

[Daald]

I also wonder why they didn't realize they were nose up? The other pilots seemed stumped and I am guessing they were looking at the displays and there is an instrument that shows which way you are pointing at the horizon.

 

[I Ratant]

I've only played flight sims, but my reaction when the view starts shaking (simulating a stall) is to push forward on the stick. (Or give bottom rudder, it depends on how I'm flying.)

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Depends on what you want out of the stall process..
Here's Ralph fighting the plane's reluctance to stall, to get it well and truly stalled!
In one week with the first Saudi Tristar, we did 242 stalls.
None of these were dangerous, but very interesting, as the plane would usually roll 90° as well as drop the nose.

 

[I Ratant]

Why would there even be a mode where the inputs are averaged together? I'm not a pilot, but I've been around aircraft my whole life and that doesn't make an ounce of sense to me.

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Airbus.... France... how about now?

 

[LTC8K6]

I also wonder why they didn't realize they were nose up? The other pilots seemed stumped and I am guessing they were looking at the displays and there is an instrument that shows which way you are pointing at the horizon.

They had to know they were nose up. The pilot was pulling back on the stick. The attitude indicator was functioning properly.

The plane was trimmed nose up as well.

They wanted to climb several times and said so.

You climb by pointing the nose up and adding power.

Unfortunately, that's not how you exit a stall.

 

[LTC8K6]

Remember that the AOA, angle of attack, is relative to the wind. A 30 degree AOA does not mean that the plane is at 30 degrees nose up.

 

[Daald]

They had to know they were nose up. The pilot was pulling back on the stick. The attitude indicator was functioning properly.

The plane was trimmed nose up as well.

They wanted to climb several times and said so.

You climb by pointing the nose up and adding power.

Unfortunately, that's not how you exit a stall.

The quotes I provided in the previous post make it seem that they did not know (Left seat and back seat). The second they realize that the right seat had the stick pulled the whole time they realize the mistake. That tells me they didn't know.

 

[AdMan]

Interesting to note that the stall warning sounded 75 times while the least experienced pilot kept pulling back on the controls.

This is what's really surprising to me (as a non-pilot who's only played around with simulators). The stall warning was sounding and not only did the pilot react incorrectly to it, but none of the pilots even mentioned that the plane was stalling, or nearly so.

Even if they didn't believe that the plane was capable of stalling, you would think that at least they would mention the alarm and try to figure out why it was going off.

 

[Skeptical Greg]

The quotes I provided in the previous post make it seem that they did not know (Left seat and back seat). The second they realize that the right seat had the stick pulled the whole time they realize the mistake. That tells me they didn't know.

The way I read it, Bonin was never trying to recover from a stall; he was trying to climb, so ' nose up ' was what he wanted to see, and why he kept the stick hard back.. It would seem the altimeter is what he ignored toward the end ..

Perhaps the other two pilots were not trusting the instrumentation, thinking Bonin was trying to recover from the stall .

 

[Daald]

The way I read it, Bonin was never trying to recover from a stall; he was trying to climb, so ' nose up ' was what he wanted to see, and why he kept the stick hard back.. It would seem the altimeter is what he ignored toward the end ..

Perhaps the other two pilots were not trusting the instrumentation, thinking Bonin was trying to recover from the stall .

I understand that is what Bonin might have wanted but why were the other two stumped? They were clearly looking for what was going wrong and couldn't figure it out. If they saw nose up they would have realized the problem. When Bonin finally told them that he has the stick back they immediately spot the problem. So the question is not why didn't Bonin react to nose up. Why didn't the other two?

 

[stilicho]

This is what's really surprising to me (as a non-pilot who's only played around with simulators). The stall warning was sounding and not only did the pilot react incorrectly to it, but none of the pilots even mentioned that the plane was stalling, or nearly so.

Even if they didn't believe that the plane was capable of stalling, you would think that at least they would mention the alarm and try to figure out why it was going off.

My experience is limited to fanatically watching episodes of Mayday! and this accident is one of a fairly comprehensive list of examples where the pilot or pilots did not believe that what was happening was possible. I am not sure what the takeaway is from this one but it's probably something along the lines of command transfer on the flight deck when specific indicators or warnings appear. The manual was fine. The aircraft design was fine.

 

[Sideroxylon]

My experience is limited to fanatically watching episodes of Mayday! and this accident is one of a fairly comprehensive list of examples where the pilot or pilots did not believe that what was happening was possible. I am not sure what the takeaway is from this one but it's probably something along the lines of command transfer on the flight deck when specific indicators or warnings appear. The manual was fine. The aircraft design was fine.

I really enjoy that show, especially for the investigation stories. Pitot tube blockage, distrust of instruments, not seeing the big picture, pilot communication failure, and continuing to pull back on the stick with stall warning, are some features of the following accidents and an incident related on the show:

China Airlines Flight 006^WP
Birgenair Flight 301^WP
Aeroperú Flight 603^WP
Colgan Air Flight 3407^WP

All are on YT.

 

[monoman]

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Depends on what you want out of the stall process..
Here's Ralph fighting the plane's reluctance to stall, to get it well and truly stalled!
In one week with the first Saudi Tristar, we did 242 stalls.
None of these were dangerous, but very interesting, as the plane would usually roll 90° as well as drop the nose.

Wow, that brought back memories. I used to fly quite often to Saudi (as a passenger) on a Tristar when my dad worked there in the early 80s. Occasionally it'd be a 747.
I remember an incident where there was fire on a Tristar and the whole roof of the plane was peeled off. Fortunately not a plane I was on, but I saw it sat on the tarmac.

With regards to the OP, do these planes have a good old manual spirit level inside of them? Could they have just rolled a ball on the floor to see that they were actually ascending?

 

[a_unique_person]

That doesn't seem to be the case.
As mentioned, there is no override; explained here..

http://msquair.wordpress.com/2011/09...ick/#more-4866

The averaging was settled on because a lockout system was seen as a potential single-point-of-failure, in what should be a redundant system..

Someone has put this spreadsheet, unfortunately just as a jpg here, but it is very good.

http://www.globalsim.web.id/publicservice/AF447/AF447TimelinePlotJuly2011v10.jpg

The pilot monitoring tells the pilot flying the correct actions to take. The PM takes control with his priority button, apparently because he does not trust the PF to do the right thing, but also because he has seniority, I would guess. The PF instantly takes control back again with his override button.

 

[a_unique_person]

They had to know they were nose up. The pilot was pulling back on the stick. The attitude indicator was functioning properly.

The plane was trimmed nose up as well.

They wanted to climb several times and said so.

You climb by pointing the nose up and adding power.

Unfortunately, that's not how you exit a stall.

That is why the Pilot Monitoring was telling the Pilot Flying to point the nose down.

 

[a_unique_person]

The way I read it, Bonin was never trying to recover from a stall; he was trying to climb, so ' nose up ' was what he wanted to see, and why he kept the stick hard back.. It would seem the altimeter is what he ignored toward the end ..

Perhaps the other two pilots were not trusting the instrumentation, thinking Bonin was trying to recover from the stall .

I think the captain worked out pretty quickly what was happening, but trying to explain it to the Pilot Flying was difficult.

2:12:27 PM: You're going up ... go down go down go down go down
2:12:30 PF: Am I going down?
2:12:XX PM: Go down
2:12:32 CP: No you're going up, now
2:12:33 PF: There I'm going up ok so let's go down

 

[Corsair 115]

The stall warning is one of the most fundamentally important warnings a pilot can get. It astonishes me that the warning was ignored to the extent it was. Has there ever been a case where a false stall warning was issued by the avionics of a commercial jetliner?

 

[LTC8K6]

The stall warning is one of the most fundamentally important warnings a pilot can get. It astonishes me that the warning was ignored to the extent it was. Has there ever been a case where a false stall warning was issued by the avionics of a commercial jetliner?

The stall warning could be false in many such situations. If the IAS is too low, either from a high AOA or maybe clogged pitot tubes, for example.

The warning is inhibited in certain scenarios, and during the beginning of stall recovery, the inhibit could be removed as conditions improve, and the stall warning will sound again, even though you have done the right thing and are actually recovering from the stall. You actually need to continue stall recovery through the false warning.

What can happen with inexperience is that you do the right thing to recover, and the stall warning comes on.

You don't realize that the warning has returned because it's no longer inhibited by a low IAS, and that it will go away again as your AOA and airspeed improve.

So you either stop the stall recovery, or you actually do the opposite. This causes the stall warning to be inhibited again, so it quits. That reinforces the idea that you are doing the right thing, when you aren't.

 

[a_unique_person]

The stall warning could be false in many such situations. If the IAS is too low, either from a high AOA or maybe clogged pitot tubes, for example.

The warning is inhibited in certain scenarios, and during the beginning of stall recovery, the inhibit could be removed as conditions improve, and the stall warning will sound again, even though you have done the right thing and are actually recovering from the stall. You actually need to continue stall recovery through the false warning.

What can happen with inexperience is that you do the right thing to recover, and the stall warning comes on.

You don't realize that the warning has returned because it's no longer inhibited by a low IAS, and that it will go away again as your AOA and airspeed improve.

So you either stop the stall recovery, or you actually do the opposite. This causes the stall warning to be inhibited again, so it quits. That reinforces the idea that you are doing the right thing, when you aren't.

There was some confusion for the PF. When the plane stalled, the airspeed dropped so low the stall warning stoppped, as the warning system does not function when air speed is too low. When he finally did dip the nose, the airspeed picked up and the stall warning came on again. So he pulled back, because that stopped the stall warning.

 

[LTC8K6]

The stall warning is one of the most fundamentally important warnings a pilot can get. It astonishes me that the warning was ignored to the extent it was. Has there ever been a case where a false stall warning was issued by the avionics of a commercial jetliner?

I didn't mean to sound like I disagreed with you. Most of those stall warnings were real, and it is strange that they seemed to ignore them.

I guess we will never know why the PF made that initial rapid climb after the A/P disconnect.