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The article misses the key takeaway from this incident IMHO. When the controls were pegged at full aft deflection, the stall warning would cease, because instr

The article misses the key takeaway from this incident IMHO. When the controls were pegged at full aft deflection, the stall warning would cease, because instrument readings in the deep stall were considered invalid by the computer. Whenever the pilot would start to push forward to recover, the computer stopped rejecting the readings, and started sounding the stall warning again! So every time the pilot started to do the right thing, the airplane would start screaming "STALL STALL" at him, and he would pull the stick back again to make it stop. I firmly believe that they would still be alive if the stall warning had either not been installed at all, or had functioned properly.

zerocrates 3y ago
This is mentioned in the article.
- jcalvinowens 3y ago
  Only in passing. The dramatized retelling through the first part of the article completely glosses over it.
_cenw 3y ago
It's important to note the stall indication itself wasn't disregarded, but the indicated airspeed (that is a prerequisite). This plane was in the exceptional situation of falling out of the sky faster than it was moving forward.
SoftTalker 3y ago
Not a pilot but I believe that pulling the stick back is exactly the wrong thing to do in a stall. The pilot should have instinctively known that pulling back on the stick would not recover a stall. On the other hand, pilots are taught to "trust the instruments" but IIRC the aircraft had no angle of attack indicator, and the airspeed tubes were frozen over. So lots of bad or missing information, contributing to stress and panic, which does strange things to otherwise normal people.
- 8ytecoder 3y ago
  Not a pilot either. And that’s what I learnt playing hours of simulator games. Isn’t gaining airspeed the primary goal?
- jcalvinowens 3y ago
  I'm a pilot. Yes, you're correct, but there was so much else going on here... unless you're certain it's wrong, you're going to be inclined to listen to the airplane when it screams at you not to do something in an already terrifying unfamiliar situation.
pazimzadeh 3y ago
> During flight 447’s plunge toward the sea, the flight directors disappeared every time the forward airspeed dropped below 60 knots. This was because an airspeed below 60 knots while in flight is so anomalous that the computers are programmed to reject such a reading as false. Furthermore, at an angle of attack threshold which corresponded quite closely to 60 knots, the stall warning would cease for exactly the same reason. This created an unfortunate correlation, wherein Bonin would pitch up, the angle of attack and airspeed would exceed the rejection thresholds, the flight director would stop telling him to fly up, and the stall warning would cease; then if he attempted to pitch down, the angle of attack data would become valid again, the flight director would tell him to pitch up, and the stall warning would return. This perverse Pavlovian relationship could have subconsciously conditioned Bonin to believe that pitching down was causing the plane to approach the stall envelope, and that by pitching up he was actually protecting the plane against stalling.
- jcalvinowens 3y ago
  Yes. That's the only place it's mentioned, IMHO it is central to the whole thing.
  - wkat4242 3y ago
    It's a really long and clear paragraph, what more do you expect? The summary blames the accident on poor training and the typical EFIS "pilot out of the loop" problem, rather than very specific issues like this. Which makes very much sense IMO.
    - jcalvinowens 3y ago
      He spends a lot more time shitting on the pilot then he does talking about this, that's backwards IMHO.
      - wkat4242 3y ago
        He doesn't really shit on the pilot IMO. He clearly states that the pilot was a product of his generation and mindset and far from the only one. He clearly states it's more of a systemic failure than an individual one. And this is only part of the many things that went wrong. Also it's important to realize the system worked as designed and in every other situation this behaviour would be beneficial. I don't think this was even changed after the accident. As one of the other things that contributed, the pilot should never have got into this situation in the first place. Which is explained by the poor stall training focusing only on low altitude stalls (which makes sense as this is by far the most likely time for them to occur, but the difference with high altitude should of course be explained as it is being done now. As with any major incident it's a matter of multiple errors compounding in just the worst way possible.
wkat4242 3y ago
Nope the article goes deep into this exact issue: > During flight 447’s plunge toward the sea, the flight directors disappeared every time the forward airspeed dropped below 60 knots. This was because an airspeed below 60 knots while in flight is so anomalous that the computers are programmed to reject such a reading as false. Furthermore, at an angle of attack threshold which corresponded quite closely to 60 knots, the stall warning would cease for exactly the same reason. This created an unfortunate correlation, wherein Bonin would pitch up, the angle of attack and airspeed would exceed the rejection thresholds, the flight director would stop telling him to fly up, and the stall warning would cease; then if he attempted to pitch down, the angle of attack data would become valid again, the flight director would tell him to pitch up, and the stall warning would return. This perverse Pavlovian relationship could have subconsciously conditioned Bonin to believe that pitching down was causing the plane to approach the stall envelope, and that by pitching up he was actually protecting the plane against stalling. This violated basic aeronautical common sense, but by this point Bonin and common sense might as well have been on different planets.
- jcalvinowens 3y ago
  Nope. One paragraph in a very long article is not "deep" at all.
deleted 3y ago
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zerocrates 3y ago

This is mentioned in the article.

jcalvinowens 3y ago
Only in passing. The dramatized retelling through the first part of the article completely glosses over it.

_cenw 3y ago

It's important to note the stall indication itself wasn't disregarded, but the indicated airspeed (that is a prerequisite). This plane was in the exceptional situation of falling out of the sky faster than it was moving forward.

SoftTalker 3y ago

Not a pilot but I believe that pulling the stick back is exactly the wrong thing to do in a stall. The pilot should have instinctively known that pulling back on the stick would not recover a stall. On the other hand, pilots are taught to "trust the instruments" but IIRC the aircraft had no angle of attack indicator, and the airspeed tubes were frozen over. So lots of bad or missing information, contributing to stress and panic, which does strange things to otherwise normal people.

8ytecoder 3y ago
Not a pilot either. And that’s what I learnt playing hours of simulator games. Isn’t gaining airspeed the primary goal?
jcalvinowens 3y ago
I'm a pilot. Yes, you're correct, but there was so much else going on here... unless you're certain it's wrong, you're going to be inclined to listen to the airplane when it screams at you not to do something in an already terrifying unfamiliar situation.

pazimzadeh 3y ago

> During flight 447’s plunge toward the sea, the flight directors disappeared every time the forward airspeed dropped below 60 knots. This was because an airspeed below 60 knots while in flight is so anomalous that the computers are programmed to reject such a reading as false. Furthermore, at an angle of attack threshold which corresponded quite closely to 60 knots, the stall warning would cease for exactly the same reason. This created an unfortunate correlation, wherein Bonin would pitch up, the angle of attack and airspeed would exceed the rejection thresholds, the flight director would stop telling him to fly up, and the stall warning would cease; then if he attempted to pitch down, the angle of attack data would become valid again, the flight director would tell him to pitch up, and the stall warning would return. This perverse Pavlovian relationship could have subconsciously conditioned Bonin to believe that pitching down was causing the plane to approach the stall envelope, and that by pitching up he was actually protecting the plane against stalling.

jcalvinowens 3y ago
Yes. That's the only place it's mentioned, IMHO it is central to the whole thing.
- wkat4242 3y ago
  It's a really long and clear paragraph, what more do you expect? The summary blames the accident on poor training and the typical EFIS "pilot out of the loop" problem, rather than very specific issues like this. Which makes very much sense IMO.
  - jcalvinowens 3y ago
    He spends a lot more time shitting on the pilot then he does talking about this, that's backwards IMHO.
    - wkat4242 3y ago
      He doesn't really shit on the pilot IMO. He clearly states that the pilot was a product of his generation and mindset and far from the only one. He clearly states it's more of a systemic failure than an individual one. And this is only part of the many things that went wrong. Also it's important to realize the system worked as designed and in every other situation this behaviour would be beneficial. I don't think this was even changed after the accident. As one of the other things that contributed, the pilot should never have got into this situation in the first place. Which is explained by the poor stall training focusing only on low altitude stalls (which makes sense as this is by far the most likely time for them to occur, but the difference with high altitude should of course be explained as it is being done now. As with any major incident it's a matter of multiple errors compounding in just the worst way possible.

wkat4242 3y ago

Nope the article goes deep into this exact issue: > During flight 447’s plunge toward the sea, the flight directors disappeared every time the forward airspeed dropped below 60 knots. This was because an airspeed below 60 knots while in flight is so anomalous that the computers are programmed to reject such a reading as false. Furthermore, at an angle of attack threshold which corresponded quite closely to 60 knots, the stall warning would cease for exactly the same reason. This created an unfortunate correlation, wherein Bonin would pitch up, the angle of attack and airspeed would exceed the rejection thresholds, the flight director would stop telling him to fly up, and the stall warning would cease; then if he attempted to pitch down, the angle of attack data would become valid again, the flight director would tell him to pitch up, and the stall warning would return. This perverse Pavlovian relationship could have subconsciously conditioned Bonin to believe that pitching down was causing the plane to approach the stall envelope, and that by pitching up he was actually protecting the plane against stalling. This violated basic aeronautical common sense, but by this point Bonin and common sense might as well have been on different planets.

jcalvinowens 3y ago
Nope. One paragraph in a very long article is not "deep" at all.

deleted 3y ago

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