6 ms·

The difference with AF447 was that the aircraft at no point was defective, it was purely confusion on part of the flight crew and the issue with two pilots "in

The difference with AF447 was that the aircraft at no point was defective, it was purely confusion on part of the flight crew and the issue with two pilots "in control" which the Captain absolutely should have dealt with.

detritus 6y ago
I thought the pitot tube 'failed' by getting iced up? I'm not sure of that's a common thing to happen though. Obviously the subsequent decisions were what ultimately led to the disaster.
js2 6y ago
The pitot tubes had iced-over and it wasn't the first time: https://en.wikipedia.org/wiki/Air_France_Flight_447#Pitot_tubes https://en.wikipedia.org/wiki/Air_France_Flight_447#Pitot_tu... But that's not what made me nervous about Airbus. Rather, that's when I learned that Airbuses are flown by side-sticks that aren't mechanically linked while Boeings are flown by yokes which are. https://en.wikipedia.org/wiki/Air_France_Flight_447#Side-stick_control_issue https://en.wikipedia.org/wiki/Air_France_Flight_447#Side-sti... The idea that two pilots can provide conflicting inputs without realizing it bothers me from a design standpoint.
- pirocks 6y ago
  Pitot tubes icing over is common on all planes not just Airbus planes. It's more or less expected and planned for.
  - js2 6y ago
    I’m not a pilot. I’ve just read the Wikipedia page on this crash and the final report. I don’t know what is common or expected and planned for but I take your characterization to mean that you think that it’s not a significant problem. There’s three pitot tubes. There were ADs issued over them icing over. Airbus replaced them multiple times with tubes from different vendors. In the final report, the first major issue is “Temporary inconsistency between the measured speeds, likely as a result of the obstruction of the pitot tubes by ice crystals, caused autopilot disconnection and reconfiguration to alternate law.” Icing over of pitot tubes seems more significant to me than I think you’re making it out to be.
    - temp667 6y ago
      It really highlights how terribly trained the pilots involved are - temporary inconsistency in measured speeds (there are still plenty of reasonable speed sources) in almost all other planes does not result in the plane crashing. Heck, my GPS can do groundspeed easily enough and you have basic pitch and power settings. How did they not notice their altitude was climbing as they pulled the plane up - they got into a CLIMB rate of 7,000 feet per minute - that's STUPID! WHY climb like that? This has nothing to do with airspeed. The stall alarm goes off 75 times! They reduce power to idle for a bit?? It's total nonsense, anyone who has flown a single engine cessna for 200 hours or more would have been able to get out of this easily just based on stall buffet and stall alarms.
      - dxdm 6y ago
        Or you underestimate the complexity of the situation and overestimate how a 200-hour Cessna pilot would have performed in that cockpit that night.
      - imtringued 6y ago
        I'm not sure what accident you are talking about but the MCAS in the 737 Max overrode pilot input. The real problem was that pilots did not know that the MCAS existed, nor did they know how to disable it.
        markus92 6y ago
        He's talking about AF447, which involved an Airbus.
  - knaq 6y ago
    No, large aircraft have pitot tube heaters. Flying in non-visual conditions without working pitot tubes would be crazy. There are aircraft, for example the B-2, that can't fly at all without working pitot tubes.
- dingaling 6y ago
  > while Boeings are flown by yokes which are [mechanically linked] They can still be disconnected with sufficient opposite force, there's a shearable torque tube between them.
  - FabHK 6y ago
    Indeed, but you'd definitely notice (unlike on the Airbus). Furthermore, if I'm not mistaken, you'd then have a split elevator (one side up, one side down), while the Airbus just averages the two inputs and sets the elevator there, conceptually.
- getpost 6y ago
  The advantages of fly-by-wire are too good to pass up, so that leaves the question of how to design an FBW system. A high school teacher of mine in the 1970s predicted an accident like AF447. He framed it this way: the 'American' approach is to implement FBW to always do what the pilot inputs indicate, whereas the 'French' approach is to do the right thing, and override the pilot if the FBW 'knows' better. That's an interesting cultural cultural consistency as well! So, the 'American' approach is better if the sensors are not working as expected, and it makes the software simpler. The 'French' approach is better if the pilot is wrong, but both the sensors and the software must be working perfectly. Everyone makes mistakes, and all software has bugs. What to do? (In reality, some 'judgement' is needed by the software, even in the American approach.) EDIT: That said, some of the design choices in the Airbus FBW are baffling, such as making the control input the average of two different inputs. I like to think AF447 is less likely to have happened in a Boeing ship, although the ulitimate cause of the crash was a pilot making what amounts to a beginner mistake. Don't miss William Langewiesche's article! https://www.vanityfair.com/news/business/2014/10/air-france-flight-447-crash https://www.vanityfair.com/news/business/2014/10/air-france-...
  - js2 6y ago
    > although the ulitimate cause of the crash was a pilot making what amounts to a beginner mistake. But it was only one of the pilots, the right-side pilot, who continued to hold the stick back and and retained command. The left-side pilot didn't realize that was occurring until it was too late.
  - stouset 6y ago
    None of this is relevant to the actual issue raised by the GP: the yokes of the pilot and co-pilot are not mechanically linked. They can be mechanically linked even with a FBW system. And personally, as someone with a bit of flying experience myself, I can't comprehend why you'd want them to not be mechanically linked. The opportunity for confusion with conflicting inputs is too damn high.
    - getpost 6y ago
      Mechanically linking is heavier than fbw/electrical/fiber optic linking, and what's the point if there's no mechanical linkage to the control surfaces? With the fbw system, the software makes the choice on how to interpret the control movement, use one or both? If one, which one? EDIT: Maybe you mean that a mechanical linkage would provide a feedback mechanism, so that one pilot would know if the other pilot was attempting an input? I don't know if there's force feedback on Airbus flight controls.
deleted 6y ago
[deleted]
kirykl 6y ago
The stall warning stopped when the plane was too far into a stall to consider the data valid. I’d say that’s a malfunction for usability. It caused the pilot to keep pulling back because that stopped the warning.
iso1631 6y ago
I won't fly Air France, not just because of AF447, but also the time they diverted into an airport in the middle of a civil war and had a whip round in first class to pay for the gas to get out of there. https://www.independent.ie/life/travel/travel-news/air-france-has-whip-around-among-passengers-to-pay-for-fuel-after-emergency-stop-in-syria-26887990.html https://www.independent.ie/life/travel/travel-news/air-franc...
- jedberg 6y ago
  I won't fly Air France because they cost me 500 euros for nothing. I was in Paris and set to leave and they went on strike. I waited in line for hours to try and get on any flight out, and they said there was no chance I would leave that day, and I should book a hotel. So we booked the cheapest thing we could find that would work with our baby, and it was 500 euros for the night. Two hours later they called us and told us to get to the airport right away if we wanted to leave France in less than a week. So we left France on small plane, and couldn't get a refund on the hotel because it was less than 24. All because they couldn't figure out how to get us on that flight two hours earlier when I was at their customer service desk.
  - ethbr0 6y ago
    Your misconception was assuming people in Paris cared about you. It is my experience that they barely care about other Parisians, and effectively negatively about anyone else.
- hourislate 6y ago
  I can understand why but a part of me is left thinking, what an adventure that could have been. Sitting around over a drink and telling your story of the time you got caught up in the Syrian Civil War.
knaq 6y ago
It sure looks defective to me: It was controlled more by pressure than movement, using joysticks instead of the traditional huge yoke. When one person was screwing up, the other could not observe this. On a Boeing, each person would feel the other person's force because the controls are physically linked. The stall warning was designed for mild stalls, not severe stalls, and would turn off if the stall was really bad. They got into that state. Every time they reduced the stall, they would get back into the range in which the warning would alert. This caused them to go back into the worse condition, in which the stall warning just gave up. The pitot tubes, used to sense speed, were prone to clogging with ice. Better equipment is expected on a large passenger plane. That's all the aircraft itself. If you want to blame the pilots for any of that, then Boeing can rightly say the same for 737 troubles.
- NikolaeVarius 6y ago
  Notice how 5/6 reasons the accident report contains are "crew screwed up"
  - js2 6y ago
    That's a "you're holding it wrong" argument. There are always human factors, no matter how well trained. So while the errors these pilots made shouldn't have happened if they were better trained, at least one of the errors, fighting over who was controlling the plane w/o realizing it, is impossible in a Boeing cockpit.
    - NikolaeVarius 6y ago
      No its not. The point of these reports is to get to the "primary causes" of the accident and include design decisions that contribute to an accident. These are trained pilots who did not follow their training. They didn't follow procedures that were in place for these types of events. They did not follow cockpit management procedures. They didnt know how to properly deal with stall conditions, a fundamental piloting skill. They managed to crash a airplane that was flying perfectly fine. I don't understand the fixation on the sidestick. Its not like they just tossed it in there. Thousands of engineer hours were spent creating the systems to manage control inputs. It may have been a contributing factor, but the sidestick isn't even mentioned in the proposed improvements section. This was pilot failure.

detritus 6y ago

I thought the pitot tube 'failed' by getting iced up? I'm not sure of that's a common thing to happen though. Obviously the subsequent decisions were what ultimately led to the disaster.

js2 6y ago

The pitot tubes had iced-over and it wasn't the first time: https://en.wikipedia.org/wiki/Air_France_Flight_447#Pitot_tubes https://en.wikipedia.org/wiki/Air_France_Flight_447#Pitot_tu... But that's not what made me nervous about Airbus. Rather, that's when I learned that Airbuses are flown by side-sticks that aren't mechanically linked while Boeings are flown by yokes which are. https://en.wikipedia.org/wiki/Air_France_Flight_447#Side-stick_control_issue https://en.wikipedia.org/wiki/Air_France_Flight_447#Side-sti... The idea that two pilots can provide conflicting inputs without realizing it bothers me from a design standpoint.

pirocks 6y ago
Pitot tubes icing over is common on all planes not just Airbus planes. It's more or less expected and planned for.
- js2 6y ago
  I’m not a pilot. I’ve just read the Wikipedia page on this crash and the final report. I don’t know what is common or expected and planned for but I take your characterization to mean that you think that it’s not a significant problem. There’s three pitot tubes. There were ADs issued over them icing over. Airbus replaced them multiple times with tubes from different vendors. In the final report, the first major issue is “Temporary inconsistency between the measured speeds, likely as a result of the obstruction of the pitot tubes by ice crystals, caused autopilot disconnection and reconfiguration to alternate law.” Icing over of pitot tubes seems more significant to me than I think you’re making it out to be.
  - temp667 6y ago
    It really highlights how terribly trained the pilots involved are - temporary inconsistency in measured speeds (there are still plenty of reasonable speed sources) in almost all other planes does not result in the plane crashing. Heck, my GPS can do groundspeed easily enough and you have basic pitch and power settings. How did they not notice their altitude was climbing as they pulled the plane up - they got into a CLIMB rate of 7,000 feet per minute - that's STUPID! WHY climb like that? This has nothing to do with airspeed. The stall alarm goes off 75 times! They reduce power to idle for a bit?? It's total nonsense, anyone who has flown a single engine cessna for 200 hours or more would have been able to get out of this easily just based on stall buffet and stall alarms.
    - dxdm 6y ago
      Or you underestimate the complexity of the situation and overestimate how a 200-hour Cessna pilot would have performed in that cockpit that night.
    - imtringued 6y ago
      I'm not sure what accident you are talking about but the MCAS in the 737 Max overrode pilot input. The real problem was that pilots did not know that the MCAS existed, nor did they know how to disable it.
      - markus92 6y ago
        He's talking about AF447, which involved an Airbus.
- knaq 6y ago
  No, large aircraft have pitot tube heaters. Flying in non-visual conditions without working pitot tubes would be crazy. There are aircraft, for example the B-2, that can't fly at all without working pitot tubes.
dingaling 6y ago
> while Boeings are flown by yokes which are [mechanically linked] They can still be disconnected with sufficient opposite force, there's a shearable torque tube between them.
- FabHK 6y ago
  Indeed, but you'd definitely notice (unlike on the Airbus). Furthermore, if I'm not mistaken, you'd then have a split elevator (one side up, one side down), while the Airbus just averages the two inputs and sets the elevator there, conceptually.
getpost 6y ago
The advantages of fly-by-wire are too good to pass up, so that leaves the question of how to design an FBW system. A high school teacher of mine in the 1970s predicted an accident like AF447. He framed it this way: the 'American' approach is to implement FBW to always do what the pilot inputs indicate, whereas the 'French' approach is to do the right thing, and override the pilot if the FBW 'knows' better. That's an interesting cultural cultural consistency as well! So, the 'American' approach is better if the sensors are not working as expected, and it makes the software simpler. The 'French' approach is better if the pilot is wrong, but both the sensors and the software must be working perfectly. Everyone makes mistakes, and all software has bugs. What to do? (In reality, some 'judgement' is needed by the software, even in the American approach.) EDIT: That said, some of the design choices in the Airbus FBW are baffling, such as making the control input the average of two different inputs. I like to think AF447 is less likely to have happened in a Boeing ship, although the ulitimate cause of the crash was a pilot making what amounts to a beginner mistake. Don't miss William Langewiesche's article! https://www.vanityfair.com/news/business/2014/10/air-france-flight-447-crash https://www.vanityfair.com/news/business/2014/10/air-france-...
- js2 6y ago
  > although the ulitimate cause of the crash was a pilot making what amounts to a beginner mistake. But it was only one of the pilots, the right-side pilot, who continued to hold the stick back and and retained command. The left-side pilot didn't realize that was occurring until it was too late.
- stouset 6y ago
  None of this is relevant to the actual issue raised by the GP: the yokes of the pilot and co-pilot are not mechanically linked. They can be mechanically linked even with a FBW system. And personally, as someone with a bit of flying experience myself, I can't comprehend why you'd want them to not be mechanically linked. The opportunity for confusion with conflicting inputs is too damn high.
  - getpost 6y ago
    Mechanically linking is heavier than fbw/electrical/fiber optic linking, and what's the point if there's no mechanical linkage to the control surfaces? With the fbw system, the software makes the choice on how to interpret the control movement, use one or both? If one, which one? EDIT: Maybe you mean that a mechanical linkage would provide a feedback mechanism, so that one pilot would know if the other pilot was attempting an input? I don't know if there's force feedback on Airbus flight controls.

deleted 6y ago

[deleted]

kirykl 6y ago

The stall warning stopped when the plane was too far into a stall to consider the data valid. I’d say that’s a malfunction for usability. It caused the pilot to keep pulling back because that stopped the warning.

iso1631 6y ago

I won't fly Air France, not just because of AF447, but also the time they diverted into an airport in the middle of a civil war and had a whip round in first class to pay for the gas to get out of there. https://www.independent.ie/life/travel/travel-news/air-france-has-whip-around-among-passengers-to-pay-for-fuel-after-emergency-stop-in-syria-26887990.html https://www.independent.ie/life/travel/travel-news/air-franc...

jedberg 6y ago
I won't fly Air France because they cost me 500 euros for nothing. I was in Paris and set to leave and they went on strike. I waited in line for hours to try and get on any flight out, and they said there was no chance I would leave that day, and I should book a hotel. So we booked the cheapest thing we could find that would work with our baby, and it was 500 euros for the night. Two hours later they called us and told us to get to the airport right away if we wanted to leave France in less than a week. So we left France on small plane, and couldn't get a refund on the hotel because it was less than 24. All because they couldn't figure out how to get us on that flight two hours earlier when I was at their customer service desk.
- ethbr0 6y ago
  Your misconception was assuming people in Paris cared about you. It is my experience that they barely care about other Parisians, and effectively negatively about anyone else.
hourislate 6y ago
I can understand why but a part of me is left thinking, what an adventure that could have been. Sitting around over a drink and telling your story of the time you got caught up in the Syrian Civil War.

knaq 6y ago

It sure looks defective to me: It was controlled more by pressure than movement, using joysticks instead of the traditional huge yoke. When one person was screwing up, the other could not observe this. On a Boeing, each person would feel the other person's force because the controls are physically linked. The stall warning was designed for mild stalls, not severe stalls, and would turn off if the stall was really bad. They got into that state. Every time they reduced the stall, they would get back into the range in which the warning would alert. This caused them to go back into the worse condition, in which the stall warning just gave up. The pitot tubes, used to sense speed, were prone to clogging with ice. Better equipment is expected on a large passenger plane. That's all the aircraft itself. If you want to blame the pilots for any of that, then Boeing can rightly say the same for 737 troubles.

NikolaeVarius 6y ago
Notice how 5/6 reasons the accident report contains are "crew screwed up"
- js2 6y ago
  That's a "you're holding it wrong" argument. There are always human factors, no matter how well trained. So while the errors these pilots made shouldn't have happened if they were better trained, at least one of the errors, fighting over who was controlling the plane w/o realizing it, is impossible in a Boeing cockpit.
  - NikolaeVarius 6y ago
    No its not. The point of these reports is to get to the "primary causes" of the accident and include design decisions that contribute to an accident. These are trained pilots who did not follow their training. They didn't follow procedures that were in place for these types of events. They did not follow cockpit management procedures. They didnt know how to properly deal with stall conditions, a fundamental piloting skill. They managed to crash a airplane that was flying perfectly fine. I don't understand the fixation on the sidestick. Its not like they just tossed it in there. Thousands of engineer hours were spent creating the systems to manage control inputs. It may have been a contributing factor, but the sidestick isn't even mentioned in the proposed improvements section. This was pilot failure.