4 ms·

In the AF447 case, the lack of feedback/linkage of the Pilot Flying / Nonflying sidesticks was a big contributing factor. It is true that the Pitot tubes froze

by rmk 4y ago

In the AF447 case, the lack of feedback/linkage of the Pilot Flying / Nonflying sidesticks was a big contributing factor. It is true that the Pitot tubes froze up. But the Pilot was roused from his sleep, entered the cockpit, and correctly pointed out that the plane was actually in a dive. It's just that the guys flying were making opposite inputs over an extended period, and it was too late to recover, which doomed AF447. Overall, Airbus and its delinked sidesticks was a factor in the accident. I thought Boeing did not have sidesticks, and the yokes/control columns are linked to give actual feedback (to emulate most airplanes, which do this with mechanical controls). Is that not the case?

jandrese 4y ago
That does seem to be what was happening here, as both pilots thought the plane was fighting their inputs, but in reality they were fighting each other.
inferiorhuman 4y ago
There were lots of things that went wrong with AF 447 but the side sticks were a minor detail. If anything the stall warning going on and off was a much bigger factor because the one pilot kept pulling back on the stick which is the exact opposite of what he should've done. Had the pilot flying simply flown pitch and power they would've been fine and had plenty of time to calmly troubleshoot the situation. > I thought Boeing did not have sidesticks, and the > yokes/control columns are linked to give actual feedback > (to emulate most airplanes, which do this with mechanical > controls). Is that not the case? Boeing's philosophy seems to be to provide physical feedback for most or all of the controls. So, yeah, the control columns are linked (even on fly-by-wire planes like the 777 and 787). But that's not very useful once you're dealing with startled and/or panicked pilots. Take a look at the Atlas Air or Sriwijaya Air crashes. The problem with Air France has nothing to do with Boeing or Airbus and everything to do with pilot standards and training. At this point Air France is lucky. Look at the Air France incident in 2020 (A318). Or their incident in Bogota in 2017 (A340). Or the 2011, 2012 x2, and 2013 incidents where the Airbus (A320/321) alpha floor protection prevented an Air France crew from crashing on approach to Marseille x2, Hamburg, and Tel Aviv. At some point Air France's luck will run out.
- travisgriggs 4y ago
  > If anything the stall warning going on and off was a much bigger factor because the one pilot kept pulling back on the stick which is the exact opposite of what he should've done. Private pilot here. This is so hard. It’s not an excuse, especially for professional pilots. But I can share from experience how much your “animal brain” fights you in this situation. Pulling back leverages lift in most normal flight, until you go too slow (stall), and then you suddenly very much need to do the opposite. But the normal behavior becomes second nature, like walking. My examiner in 2020 said the biggest thing the FAA was stressing about was a serious uptick in incidents with slow flight (and stall) handling during takeoff/landings. A year ago, we had an experienced local private pilot wreck his plane (lucky no major injuries) succumbing to exactly this. Took off, lift conditions a little worse than normal, started to leave ground effect, felt the plane stall, pulled back, started losing altitude, panicked and pulled back harder, tailed down and fell side wards. Plane totaled. He recounted to me after how he knew what to do. He’s trained multiple times. Done lots of stall recovery. Has done many many short field takeoffs (which is similar, pop the plane off the ground and then stay low to build speed). But was still chagrined at how panick/situation management got the better of him that time. Being master of your animal brain in all situations is hard. And you never know, because you can never test all situations.
  - inferiorhuman 4y ago
    Sure. There are some things in aviation that are counterintuitive: recovering from a stall is one of those. That's why commercial aviation in the United States places such a strong emphasis on regular training (and why commercial aviation in the US is as safe as it is). Unfortunately stall physics are something that flight simulators don't tend to do so well at. Another counterintuitive thing is that tactile feedback isn't necessarily helpful. There's a lot of whinging about how Airbus doesn't provide any feedback in the sidestick when both pilots are doing conflicting things, same with the thrust levers (or whatever they're called in Airbus land). Pilots have crashed Boeing airliners that give you this "important" feedback. Anyways, my point was that stall recovery is something that's usually drilled into pilots. Unfortunately for the AF 447 crew, nobody told them that the stall warning would turn off when they flew so far outside the envelope that they were in "undefined behavior" territory. And that led to at least one of the pilots not recognizing that they'd stalled in the first place. But like any crash there are many contributing factors, and if any one of those had been different the plane wouldn't have crashed. If it were just one or two examples of poor airmanship at Air France then sure, it'd be easy to chalk it up to "flying is hard". And yeah, the pandemic has robbed a lot of pilots of their necessary practice. But the four or five cases I cited where Airbus' "alpha floor protection" saved Air France flights were all pre-pandemic. At some point you've gotta look at what those incidents and accidents have in common (hint: it's not the airplane and not the crew). And that's why my main concern is with Air France's lack of safety culture and by extension their pilot training.
hindsightbias 4y ago
The transcripts of AF447 include the pilot telling the right seater to stop. More than once. But he keeps doing inputs. Airbus 320 pilot told me there is a light that comes on when inputs dont match. Now reread the transcripts with the assumption that the right seater might not have the best intentions.
- deleted 4y ago
  [deleted]
- cm2187 4y ago
  What do you mean by best intentions? There are more efficient ways to crash a plane. But also isn't the right seater the first officier, surely he should obey a repeated direct order from the captain.
  - jonsen 4y ago
    The captain was asleep. Maybe there were no clear consensus on chain of command in the cockpit.
  - rmk 4y ago
    By convention the left seater is the captain. In the case of AF447, the captain was asleep, and the FO and a relief pilot were flying the plane.
formerly_proven 4y ago
> Overall, Airbus and its delinked sidesticks was a factor in the accident. Confused, Bonin exclaimed, "[Expletive] I don't have control of the airplane any more now", and two seconds later, "I don't have control of the airplane at all!"[29] Robert responded to this by saying, "controls to the left", and took over control of the aircraft.[73][32] He pushed his side-stick forward to lower the nose and recover from the stall; however, Bonin was still pulling his side-stick back. The inputs cancelled each other out and triggered an audible "dual input" warning. -- So in an Airbus this situation is unambiguous - the plane tells you plain and simple: Both pilots are trying to fly at the same time. With a mechanically linked set of controls, you don't necessarily know whether you're fighting the other pilot or the plane.

by rmk 4y ago

jandrese 4y ago

That does seem to be what was happening here, as both pilots thought the plane was fighting their inputs, but in reality they were fighting each other.

inferiorhuman 4y ago

There were lots of things that went wrong with AF 447 but the side sticks were a minor detail. If anything the stall warning going on and off was a much bigger factor because the one pilot kept pulling back on the stick which is the exact opposite of what he should've done. Had the pilot flying simply flown pitch and power they would've been fine and had plenty of time to calmly troubleshoot the situation. > I thought Boeing did not have sidesticks, and the > yokes/control columns are linked to give actual feedback > (to emulate most airplanes, which do this with mechanical > controls). Is that not the case? Boeing's philosophy seems to be to provide physical feedback for most or all of the controls. So, yeah, the control columns are linked (even on fly-by-wire planes like the 777 and 787). But that's not very useful once you're dealing with startled and/or panicked pilots. Take a look at the Atlas Air or Sriwijaya Air crashes. The problem with Air France has nothing to do with Boeing or Airbus and everything to do with pilot standards and training. At this point Air France is lucky. Look at the Air France incident in 2020 (A318). Or their incident in Bogota in 2017 (A340). Or the 2011, 2012 x2, and 2013 incidents where the Airbus (A320/321) alpha floor protection prevented an Air France crew from crashing on approach to Marseille x2, Hamburg, and Tel Aviv. At some point Air France's luck will run out.

travisgriggs 4y ago
> If anything the stall warning going on and off was a much bigger factor because the one pilot kept pulling back on the stick which is the exact opposite of what he should've done. Private pilot here. This is so hard. It’s not an excuse, especially for professional pilots. But I can share from experience how much your “animal brain” fights you in this situation. Pulling back leverages lift in most normal flight, until you go too slow (stall), and then you suddenly very much need to do the opposite. But the normal behavior becomes second nature, like walking. My examiner in 2020 said the biggest thing the FAA was stressing about was a serious uptick in incidents with slow flight (and stall) handling during takeoff/landings. A year ago, we had an experienced local private pilot wreck his plane (lucky no major injuries) succumbing to exactly this. Took off, lift conditions a little worse than normal, started to leave ground effect, felt the plane stall, pulled back, started losing altitude, panicked and pulled back harder, tailed down and fell side wards. Plane totaled. He recounted to me after how he knew what to do. He’s trained multiple times. Done lots of stall recovery. Has done many many short field takeoffs (which is similar, pop the plane off the ground and then stay low to build speed). But was still chagrined at how panick/situation management got the better of him that time. Being master of your animal brain in all situations is hard. And you never know, because you can never test all situations.
- inferiorhuman 4y ago
  Sure. There are some things in aviation that are counterintuitive: recovering from a stall is one of those. That's why commercial aviation in the United States places such a strong emphasis on regular training (and why commercial aviation in the US is as safe as it is). Unfortunately stall physics are something that flight simulators don't tend to do so well at. Another counterintuitive thing is that tactile feedback isn't necessarily helpful. There's a lot of whinging about how Airbus doesn't provide any feedback in the sidestick when both pilots are doing conflicting things, same with the thrust levers (or whatever they're called in Airbus land). Pilots have crashed Boeing airliners that give you this "important" feedback. Anyways, my point was that stall recovery is something that's usually drilled into pilots. Unfortunately for the AF 447 crew, nobody told them that the stall warning would turn off when they flew so far outside the envelope that they were in "undefined behavior" territory. And that led to at least one of the pilots not recognizing that they'd stalled in the first place. But like any crash there are many contributing factors, and if any one of those had been different the plane wouldn't have crashed. If it were just one or two examples of poor airmanship at Air France then sure, it'd be easy to chalk it up to "flying is hard". And yeah, the pandemic has robbed a lot of pilots of their necessary practice. But the four or five cases I cited where Airbus' "alpha floor protection" saved Air France flights were all pre-pandemic. At some point you've gotta look at what those incidents and accidents have in common (hint: it's not the airplane and not the crew). And that's why my main concern is with Air France's lack of safety culture and by extension their pilot training.

hindsightbias 4y ago

The transcripts of AF447 include the pilot telling the right seater to stop. More than once. But he keeps doing inputs. Airbus 320 pilot told me there is a light that comes on when inputs dont match. Now reread the transcripts with the assumption that the right seater might not have the best intentions.

deleted 4y ago
[deleted]
cm2187 4y ago
What do you mean by best intentions? There are more efficient ways to crash a plane. But also isn't the right seater the first officier, surely he should obey a repeated direct order from the captain.
- jonsen 4y ago
  The captain was asleep. Maybe there were no clear consensus on chain of command in the cockpit.
- rmk 4y ago
  By convention the left seater is the captain. In the case of AF447, the captain was asleep, and the FO and a relief pilot were flying the plane.

formerly_proven 4y ago

> Overall, Airbus and its delinked sidesticks was a factor in the accident. Confused, Bonin exclaimed, "[Expletive] I don't have control of the airplane any more now", and two seconds later, "I don't have control of the airplane at all!"[29] Robert responded to this by saying, "controls to the left", and took over control of the aircraft.[73][32] He pushed his side-stick forward to lower the nose and recover from the stall; however, Bonin was still pulling his side-stick back. The inputs cancelled each other out and triggered an audible "dual input" warning. -- So in an Airbus this situation is unambiguous - the plane tells you plain and simple: Both pilots are trying to fly at the same time. With a mechanically linked set of controls, you don't necessarily know whether you're fighting the other pilot or the plane.