Air France pilots and high altitude stall training

[jtrain609]

Sounds like the French investigators, who I'm assuming at the equivalent of the NTSB, say that the Air France first officers who were up front when their plane crashed into the Atlantic didn't have, and didn't know how to recover from a high altitude stall.

http://www.bea.aero/fr/enquetes/vol.af.447/note29juillet2011.en.pdf

To a lot of folks, a lack of training on high altitude stall recovery has been a glaring problem with training programs in the states, and I'm willing to bet that our old stall recovery techniques would have resulted in the same condition that these Air France guys found themselves in. The new stall recovery techniques should get the nose down far enough to fly out of it, but before, the technique was to lose as little altitude as possible and power out of the stall, which is obviously impossible at higher altitudes, and tenuous at best at lower altitudes.

 

[zmiller4]

Old stall recovery techniques were nuts. The new ones lose very little altitude, which makes it seem how they were taught before pretty dumb.

At least one regional includes high altitude stalls in training...it's crazy how nose down you have to get and how easy it is to stall again with too early a recovery.

 

[jtrain609]

Old stall recovery techniques were nuts. The new ones lose very little altitude, which makes it seem how they were taught before pretty dumb.

At least one regional includes high altitude stalls in training...it's crazy how nose down you have to get and how easy it is to stall again with too early a recovery.

Indeed. I don't have a training syllabus in front of me, but I don't think we cover it. The better instructors will show you one if there's any extra time in the sim.

 

[nc1982]

I know when I was in the CRJ900, we did high altitude stall recoveries. I don't know if it was in the syllabus or if it was just one of those check off the box type of thing. But man it's crazy. We were at FL370 when we did it and the amount of altitude you have to lose is just nuts. The buffer between the low speed cue and the high speed cue was maybe 30 knots. I think we lost about 5000 feet before we could start recovering.

 

[beasly]

That was a heart-wrenching read.

 

[Pilotforhire587]

I know when I was in the CRJ900, we did high altitude stall recoveries. I don't know if it was in the syllabus or if it was just one of those check off the box type of thing. But man it's crazy. We were at FL370 when we did it and the amount of altitude you have to lose is just nuts. The buffer between the low speed cue and the high speed cue was maybe 30 knots. I think we lost about 5000 feet before we could start recovering.

Have you ever seen the video of the Top Gear guy flying the U2, in cruise they only have about 5 knots between overspeed and stall up at 70k

 

[beasly]

I know when I was in the CRJ900, we did high altitude stall recoveries. I don't know if it was in the syllabus or if it was just one of those check off the box type of thing. But man it's crazy. We were at FL370 when we did it and the amount of altitude you have to lose is just nuts. The buffer between the low speed cue and the high speed cue was maybe 30 knots. I think we lost about 5000 feet before we could start recovering.

What is a 'low speed cue' and 'high speed cue'?

thx

 

[poser765]

Have you ever seen the video of the Top Gear guy flying the U2, in cruise they only have about 5 knots between overspeed and stall up at 70k

That was an AMAZING video.

 

[RDoug]

Have you ever seen the video of the Top Gear guy flying the U2, in cruise they only have about 5 knots between overspeed and stall up at 70k

I've not seen that video, but I was told that about the overspeed/stall window on the U-2 many, many years ago back in my Air Force controller days.

 

[Autothrust Blue]

To a lot of folks, a lack of training on high altitude stall recovery has been a glaring problem with training programs in the states, and I'm willing to bet that our old stall recovery techniques would have resulted in the same condition that these Air France guys found themselves in. The new stall recovery techniques should get the nose down far enough to fly out of it, but before, the technique was to lose as little altitude as possible and power out of the stall, which is obviously impossible at higher altitudes, and tenuous at best at lower altitudes.

Q: How is stall formed?
A: By exceeding the critical angle of attack.

Q: How is a stall broken?
A: By reducing angle of attack below the critical value.

Q: What normally happens when you slow a fly-by-wire Airbus down (when everything is working)?
A: Alpha prot/Alpha Floor kicks in, and you can pull all you want and not stall the airplane.

Q: What happens in alternate law (F/CTL ALTN LAW * PROT LOST *)?
A: You can stall the airplane if you exceed the critical angle of attack.

Slight change in human-machine interface there I think.

 

[BobDDuck]

What is a 'low speed cue' and 'high speed cue'?

thx

They can be various things on various airframes, but in general, on a glass display speed tape there is a green (or some other color) line at 1.27 or 1.20 Vs_currentconfig. That is basically a "do not fly below" reference. Also, there are red (normally) barber polls at Vs_currentconfig and at Vmo or Mmo. If you fall below or exceed these marks respectively, bad stuff will happen. On the high side you will get an overspeed clacker and potentially do damage to the airframe. On the low side, you will stall.

As altitude increases the distance between these two barber polls shrinks due to your indicated airspeed decreasing for a given TAS or Mach Number. In the CRJ7, by the time you get up to 41,000 there is about a 30 knot gap between the two. I've heard stories about the (I think) DC8 having a 5 knot gap at it's max altitude. This is also where the term "coffin corner" comes from.

 

[dasleben]

We did high-altitude stall recoveries in the 767 sim, and it was definitely eye-opening. It took a few thousand feet to recover, and that's if you recognized the situation you were in immediately, without all of the cascading failures that occurred along with the Air France flight in question.

Stall margins at high weights can be surprisingly small. Case in point: Departing out of the Middle East last week with a temperature of 40C and 385,000 lbs (still almost 30,000 less than MGTOW), during flap retraction the PLI was hanging 2-3 degrees above the pipper. A 40 degree banked turn, even at 230 knots and accelerating, could have resulted in a low-speed buffet. Cruise flight is generally fine, but you can still get into situations in strong turbulence where the margin becomes less than comfortable.

 

[drunkenbeagle]

We did high-altitude stall recoveries in the 767 sim, and it was definitely eye-opening. It took a few thousand feet to recover, and that's if you recognized the situation you were in immediately, without all of the cascading failures that occurred along with the Air France flight in question.

About 8,000' in the 747-400, well below MGTOW. And that was with motion turned off.

 

[klkm]

Just had a Air France flight go through a thunderstorm which caused an "uncontrollable climb 3,000ft with autopilot disconnect" words straight from the pilot. Seems like maybe they need training on how to avoid weather, then stalls and so forth are very less likely to happen. This was over the ocean as well.

 

[drunkenbeagle]

Q: What happens in alternate law (F/CTL ALTN LAW * PROT LOST *)?
A: You can stall the airplane if you exceed the critical angle of attack.

But it is not a simple and straightforward instrument. In the first place, it can develop mechanical trouble (and, as on is tempted to add, it usually does). In the second place, it has some peculiarities that must be understood before it can be used as a buoyancy meter or a stall-warning device. Ignorance of its peculiarities has cost many a pilot his life. -- Wolfgang Langewiesche, pp 73, 1944.

 

[seagull]

Q: How is stall formed?
A: By exceeding the critical angle of attack.

Q: How is a stall broken?
A: By reducing angle of attack below the critical value.

Q: What normally happens when you slow a fly-by-wire Airbus down (when everything is working)?
A: Alpha prot/Alpha Floor kicks in, and you can pull all you want and not stall the airplane.

Q: What happens in alternate law (F/CTL ALTN LAW * PROT LOST *)?
A: You can stall the airplane if you exceed the critical angle of attack.

Slight change in human-machine interface there I think.

Bingo. Most of the replies here are indicative of a lack of how complex this is, and are really just a variation of "it wouldn't have happened to me".

 

[Autothrust Blue]

Bingo. Most of the replies here are indicative of a lack of how complex this is, and are really just a variation of "it wouldn't have happened to me".

What bugs me, and what scares me, is that I can actually see this one happening to me considering the normal way that the interface works (e.g. 99.9999% of the time in that airplane). "Hey! We're a-stallin', thrust TOGA and pull!" -> Bye bye. Given the available information presented, how it's presented and how things normally work...

A killer I forgot is that there's no automatic stabilizer trim in alternate law, too. And the THS went to full airplane nose up and stayed there for the duration of the flight. You get one little line on the primary flight display 'USE MAN PITCH TRIM' to remind you to move the wheel, which you normally only touch on the ground before takeoff.

 

[BobDDuck]

I don't know the Airbus system that well (or at all really) but I do know that in other glass cockpit setups, cascading status messages are a problem. When you have serious system failures there can be multiple pages of advisory messages that are often prioritized only by warning vs. caution vs. status. I've seen situations in the sim where an extremely important message gets buried the second page of the EICAS/ECAM because the designers felt that the low oil pressure warning message from the engine that was shut down 15 minutes ago is more important. I hope that as glass systems mature and user interface designs continue to improve they figure out better message priority systems than red/yellow/white(blue) and most recent on the top.

 

[Pépé le Pilot]

The BEA released today the FDR transcript and it's heart-wrenching. At 4000ft MSL they were still trying to understand what was going on. I don't have the time right now to translate it, but if a translated version doesn't show up by tomorrow, I'll do it.

 

[drunkenbeagle]

The BEA released today the FDR transcript and it's heart-wrenching. At 4000ft MSL they were still trying to understand what was going on. I don't have the time right now to translate it, but if a translated version doesn't show up by tomorrow, I'll do it.

I'll translate it when I get home tonight.