5 ms·
> 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 airspe
by 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 agoYes. That's the only place it's mentioned, IMHO it is central to the whole thing.
- wkat4242 3y agoIt'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 agoHe spends a lot more time shitting on the pilot then he does talking about this, that's backwards IMHO.
- wkat4242 3y agoHe 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.
- pazimzadeh 3y agoI agree that they buried the lede. You might have stopped reading before it. I'm usually completionist, I'd rather skim than miss a big chunk of text.