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The lack of reaction to "Stall!" implies one of two things; either it was broken and the sound didn't play or the complete lack of understanding about what the

The lack of reaction to "Stall!" implies one of two things; either it was broken and the sound didn't play or the complete lack of understanding about what the word "Stall" meant with the pilots. Has either of these been proposed and discussed? The author of this piece doesn't seem to touch on why they ignore "Stall!", unless it's been confirmed the sound had been heard (on the recording maybe?) and they did indeed understand what "Stall" meant as it's "standard" pilot language? Why would they ignore it...

yew 15y ago
The articles says it's audible on the recording. Stall alarms are usually very loud. I can't speak for Air France, but in general aviation the word "stall" (in English) is of global significance. I imagine they thought it was malfunctioning, or simply didn't think about it in the heat of the moment.
- citricsquid 15y ago
  They don't explicitly state that it is something you can hear in the recording, I made the assumption that the "blackbox" contain not just an audio recording but a log of the computer system -- what actions it took, which is how they know the co-pilot was pulling back the entire time -- and they're basing it off of that. Although the way they phrase it (reading back through the relevant paragraphs now) with the assumption he is referring to it being audible it does read that way. I'll email the author to ask for clarification.
  - yew 15y ago
    I was thinking of ". . .even though the word "Stall!" will blare through the cockpit 75 times." Looking back over it, I suppose that's not quite what that means. . .
    - lutorm 15y ago
      No, it's exactly what that means. Search for the youtube link to the Aeroperu recording above and you'll be able to hear how much blaring there is.
      - pbhjpbhj 15y ago
        Which the pilot and co- don't know to trust as the altimeter and other instruments are giving false readings (listen to that recording, it's all due to the instruments being taped over by ground crew and the pilots missing it on pre-flight checks). If you've determined that the stall warning is false I imagine it's hard then to back out and stop filtering that noise out; particularly when you're concentrating very hard on something else. Someone mentioned a case where the pilots crashed because they were attending to a landing gear problem and so missed the lack of fuel. I wonder how men/women differ in these pressure situations too. IME women generally appear to handle multi-tasking and interrupts better than men do.
  - brc 15y ago
    There are two recordings - the 'black box' which records all the control inputs, readings, etc. Then there is the cockpit voice recorder, which is a separate recording of the pilots voices (and radio traffic, IIRC). I don't know if the two separate items are in the same 'box' or if they are physically separate, but there are definitely two different things being recorded.
  - Sharlin 15y ago
    Surely it seems obvious that if the recorder picks up the crew voices, it also picks up the very loud stall warning?
  - Angostura 15y ago
    I would imagine that if the audible stall warning had failed, this would have been a very significant issue that would have been flagged up at the head of the report.
kmort 15y ago
The author did touch on it: "According to Camilleri, not one of US Airway's 17 Airbus 330s has ever been in alternate law. Therefore, Bonin may have assumed that the stall warning was spurious because he didn't realize that the plane could remove its own restrictions against stalling and, indeed, had done so."
- citricsquid 15y ago
  by "ignore" I mean they didn't acknowledge it, they didn't once mention the obnoxious noise and the implications. Even if they believe that they could not stall the plane, would they not mention it as something to consider? Looking back on the account of events through the entire thing from start to finish was little more than 5 minutes, so maybe they didn't have time in the panic to mention it, but it still seems strange to me that at no point did someone ever say "it's stalling!", even when the captain returned he didn't acknowledge either, which just seems so strange. "We still have the engines! What the hell is happening? I don't understand what's happening." unless this is in reference to the stalling?
  - kmort 15y ago
    As the article mentions, aviation experts are rightly bamboozled by this. The closest I've come to flying was Chuck Yeager's AFT on the Commodore 64, but even then I knew presence of engine power does not preclude a stall if your pitch is extreme. Without knowing that Bonin had been pulling-back the whole time, I guess Robert and Dubois were searching for non-obvious reasons (and struggling, with the altered cognition under stress that the article also mentions).
- cellularmitosis 15y ago
  So, here's the problem with this whole normal law / alternate law situation: If a pilot believes he is in normal law, and wants to ascend above the storm, he'll probably just pull all the way back on the stick, thinking "this will cause the computer to ascend as quickly as it can without stalling". AAAARGGHH!!!! This maddening concept of normal law is turning the above insanity into the EXPECTED OUTCOME! Having a computer partially ignore your control will always lead to people railing the controls all the way in the direction they want. That's just human nature. This is just like having someone who was raised on cars with traction control drive on ice for the first time. They'll notice the car isnt accelerating as fast as it normally would, and their natural reaction will be to push the gas pedal down EVEN FURTHER! Bingo - your control system just extracted the exact opposite of rational human behavior. If they didn't have traction control, they would have heard the engine rev and the tires spinning, and they would have backed off of the gas. If the pilot weren't under the mistaken impression that the computer would limit his input, he would have NEVER pulled the stick all the way back and held it there - he instead would have been very careful to pull the stick back only just enough to ascend safely. The airline industry may think normal law is a feature. I consider it an abomination You either give the human full control, or cut their control entirely. You DO NOT give them partially limited control. That only encourages exaggerated inputs.
deleted 15y ago
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hristov 15y ago
In many cases people do not mention the obvious. If there is a stall alarm blaring, I do not think any pilot would actually say "the stall alarm is on". So I do not think it too surprising that nobody mentioned stall in conversation. Now about why they did not put the nose down, it seems either that (i) they were both under the impression that the electronic controls would not let them stall; or (ii) from their experience with smaller planes they thought they would be more pronounced shaking and other physical clues when the plane did stall. Also it seems that they were much more scared of the storm than stalling so they just wanted to escape it.
sowbug 15y ago
The Invisible Gorilla by Christopher Chabris and Daniel Simons tries to answer this question. These guys made the video where people are supposed to count the number of basketball passes (I won't say what's actually in the video in case you haven't already seen it). The pilots were likely afflicted by a form of inattentional blindness. Their brains certainly heard the stall warnings, but they were filtering them out so that they could focus on "the important stuff." People do stuff like this all the time, like crash their cars into motorcycles because they were so preoccupied looking for oncoming automobiles (not bikes).

yew 15y ago

The articles says it's audible on the recording. Stall alarms are usually very loud. I can't speak for Air France, but in general aviation the word "stall" (in English) is of global significance. I imagine they thought it was malfunctioning, or simply didn't think about it in the heat of the moment.

citricsquid 15y ago
They don't explicitly state that it is something you can hear in the recording, I made the assumption that the "blackbox" contain not just an audio recording but a log of the computer system -- what actions it took, which is how they know the co-pilot was pulling back the entire time -- and they're basing it off of that. Although the way they phrase it (reading back through the relevant paragraphs now) with the assumption he is referring to it being audible it does read that way. I'll email the author to ask for clarification.
- yew 15y ago
  I was thinking of ". . .even though the word "Stall!" will blare through the cockpit 75 times." Looking back over it, I suppose that's not quite what that means. . .
  - lutorm 15y ago
    No, it's exactly what that means. Search for the youtube link to the Aeroperu recording above and you'll be able to hear how much blaring there is.
    - pbhjpbhj 15y ago
      Which the pilot and co- don't know to trust as the altimeter and other instruments are giving false readings (listen to that recording, it's all due to the instruments being taped over by ground crew and the pilots missing it on pre-flight checks). If you've determined that the stall warning is false I imagine it's hard then to back out and stop filtering that noise out; particularly when you're concentrating very hard on something else. Someone mentioned a case where the pilots crashed because they were attending to a landing gear problem and so missed the lack of fuel. I wonder how men/women differ in these pressure situations too. IME women generally appear to handle multi-tasking and interrupts better than men do.
- brc 15y ago
  There are two recordings - the 'black box' which records all the control inputs, readings, etc. Then there is the cockpit voice recorder, which is a separate recording of the pilots voices (and radio traffic, IIRC). I don't know if the two separate items are in the same 'box' or if they are physically separate, but there are definitely two different things being recorded.
- Sharlin 15y ago
  Surely it seems obvious that if the recorder picks up the crew voices, it also picks up the very loud stall warning?
- Angostura 15y ago
  I would imagine that if the audible stall warning had failed, this would have been a very significant issue that would have been flagged up at the head of the report.

kmort 15y ago

The author did touch on it: "According to Camilleri, not one of US Airway's 17 Airbus 330s has ever been in alternate law. Therefore, Bonin may have assumed that the stall warning was spurious because he didn't realize that the plane could remove its own restrictions against stalling and, indeed, had done so."

citricsquid 15y ago
by "ignore" I mean they didn't acknowledge it, they didn't once mention the obnoxious noise and the implications. Even if they believe that they could not stall the plane, would they not mention it as something to consider? Looking back on the account of events through the entire thing from start to finish was little more than 5 minutes, so maybe they didn't have time in the panic to mention it, but it still seems strange to me that at no point did someone ever say "it's stalling!", even when the captain returned he didn't acknowledge either, which just seems so strange. "We still have the engines! What the hell is happening? I don't understand what's happening." unless this is in reference to the stalling?
- kmort 15y ago
  As the article mentions, aviation experts are rightly bamboozled by this. The closest I've come to flying was Chuck Yeager's AFT on the Commodore 64, but even then I knew presence of engine power does not preclude a stall if your pitch is extreme. Without knowing that Bonin had been pulling-back the whole time, I guess Robert and Dubois were searching for non-obvious reasons (and struggling, with the altered cognition under stress that the article also mentions).
cellularmitosis 15y ago
So, here's the problem with this whole normal law / alternate law situation: If a pilot believes he is in normal law, and wants to ascend above the storm, he'll probably just pull all the way back on the stick, thinking "this will cause the computer to ascend as quickly as it can without stalling". AAAARGGHH!!!! This maddening concept of normal law is turning the above insanity into the EXPECTED OUTCOME! Having a computer partially ignore your control will always lead to people railing the controls all the way in the direction they want. That's just human nature. This is just like having someone who was raised on cars with traction control drive on ice for the first time. They'll notice the car isnt accelerating as fast as it normally would, and their natural reaction will be to push the gas pedal down EVEN FURTHER! Bingo - your control system just extracted the exact opposite of rational human behavior. If they didn't have traction control, they would have heard the engine rev and the tires spinning, and they would have backed off of the gas. If the pilot weren't under the mistaken impression that the computer would limit his input, he would have NEVER pulled the stick all the way back and held it there - he instead would have been very careful to pull the stick back only just enough to ascend safely. The airline industry may think normal law is a feature. I consider it an abomination You either give the human full control, or cut their control entirely. You DO NOT give them partially limited control. That only encourages exaggerated inputs.

deleted 15y ago

[deleted]

hristov 15y ago

In many cases people do not mention the obvious. If there is a stall alarm blaring, I do not think any pilot would actually say "the stall alarm is on". So I do not think it too surprising that nobody mentioned stall in conversation. Now about why they did not put the nose down, it seems either that (i) they were both under the impression that the electronic controls would not let them stall; or (ii) from their experience with smaller planes they thought they would be more pronounced shaking and other physical clues when the plane did stall. Also it seems that they were much more scared of the storm than stalling so they just wanted to escape it.

sowbug 15y ago

The Invisible Gorilla by Christopher Chabris and Daniel Simons tries to answer this question. These guys made the video where people are supposed to count the number of basketball passes (I won't say what's actually in the video in case you haven't already seen it). The pilots were likely afflicted by a form of inattentional blindness. Their brains certainly heard the stall warnings, but they were filtering them out so that they could focus on "the important stuff." People do stuff like this all the time, like crash their cars into motorcycles because they were so preoccupied looking for oncoming automobiles (not bikes).