5 ms·

Another good write up of this incident is on the excellent Admiral Cloudberg blog: https://admiralcloudberg.medium.com/the-long-shadow-of-war-the-story-of-the-

Another good write up of this incident is on the excellent Admiral Cloudberg blog: https://admiralcloudberg.medium.com/the-long-shadow-of-war-the-story-of-the-shootdown-of-iran-air-flight-655-ef7bdf1e9f75 https://admiralcloudberg.medium.com/the-long-shadow-of-war-t... Another article in that series is also related to a UX mistake: Air France Flight 447. This crashed, in part, because the inputs from two control sticks (one for pilot and other for copilot) were averaged if they disagreed, unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place, and you'd feel the other pilot fighting you. When the plane stalled, one pilot correctly pushed down to come out of the stall (after which they would be able to pull back up) while the other pulled up instead (which is wrong but does feel like the instinctively correct thing to do). The inputs cancelled out so had almost no effect. By the end both pilots were pulling up, but that hadn't been the case earlier on when the problem could have been resolved. https://admiralcloudberg.medium.com/the-long-way-down-the-crash-of-air-france-flight-447-8a7678c37982 https://admiralcloudberg.medium.com/the-long-way-down-the-cr... The captain had been on a rest brake and only re-entered the cabin at the last moment. He finally figured out the problem but it was too late to do anything. > “Go on, pull,” Dubois said. Was this comment a sardonic resignation to fate?

gregsadetsky 3y ago
The tragic AF447 flight comes up somewhat regularly on the site — see this recent conversation [0]. [0] https://news.ycombinator.com/item?id=37089363 https://news.ycombinator.com/item?id=37089363
- dredmorbius 3y ago
  CFIT is a particularly spectacular form of failure. <https://en.wikipedia.org/wiki/Controlled_flight_into_terrain https://en.wikipedia.org/wiki/Controlled_flight_into_terrain>
MichaelZuo 3y ago
It's not something that can be changed on airbus cockpits, since the nature of side sticks makes them impossible to be mechanically linked, unless there was some very complex motor system built into each stick that provided force feedback equal in strength to a pilot tugging hard on it.
- masklinn 3y ago
  > unless there was some very complex motor system built into each stick that provided force feedback equal in strength to a pilot tugging hard on it It does not have to be “equal in strength to a pilot tugging hard on it” since there is normally no significant load applied by the stick to the hand (only the centering springs). So most every feedback should be noticeable. And force feedback is being deployed right now on commercial planes. The Irkut MC-21 was supposed to be the first airliner featuring them, but the invasion of ukraine and subsequent sanctions nixed that (as the provider of the sticks is the french company Ratier-Figeac). Gulfstream’s 7th gen (GVII) also have active sticks, provided by BAE.
  - MichaelZuo 3y ago
    Yes, but then no one would consider the feedback to be the equivalent of a mechanically linked system, like what Boeing uses.
    - masklinn 3y ago
      Of course they would: the problem is that there is a lack of feedback when incompatible input is entered. Audio feedback was added since AF 447 but as well known sound is one of the first thing to be blanked out in high stress situations. Physical feedback provides a second stimulus, and one which does not get ignored as much. The planes are FBW, the side sticks have no mechanical linkage outside their control box, there is no cause for a pilot to input significant force on the stick, and thus most every feedback would be sensible. Unlike a 737, the pilots are not physically moving the control surfaces.
      - 3y ago
cesarb 3y ago
> unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place I don't know if it's true, but I recall reading somewhere that this physical connection is a breakable link, so if one of the controls gets stuck the other control can still be used to fly the airplane (after some application of strong force to break the connection).
- f1shy 3y ago
  Yes it is true. The force needed is pretty high.
- immibis 3y ago
  It also caused one accident, where both pilots thought the controls were jammed because the other pilot was pulling in the opposite direction. This is no better than averaging. At least Airbus gives an alarm.
  - ImPostingOnHN 3y ago
    Which accident was that? Thanks!
    - immibis 3y ago
      Don't remember, sorry.
      - ImPostingOnHN 3y ago
        I couldn't find any evidence of it happening either, which makes sense, a system which gives feedback there's a problem intuitively seems better than one which doesn't.
        inferiorhuman 3y ago
        a system which gives feedback there's a problem intuitively seems better than one which doesn't. Except that your intuition isn't always correct. Airbus throttle levers don't move on their own, Boeing throttle levers (at least pre-FBW) were mechanically linked to the control system and would move in response to computer inputs. Sounds safer, right? Look at the Sriwijaya Air 737 crash (among others). Even with the throttle levers showing wildly asymmetrical thrust, when the automation gave up the pilots didn't notice, didn't react properly, and crashed the plane.
masklinn 3y ago
> unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place, and you'd feel the other pilot fighting you. Note that it’s not quite that flagrant: because Boeings don’t normally autotrim (famously aside from the 737 MAX, whose MCAS was not documented and trained for — I think the more recent Boeings like 777 and 787 are FBW and do autotrim) it’s possible to fight your co-pilot while thinking you’re not trimmed, or even that you have excessive air load: > excessive air loads on the stabiliser may require effort by both pilots to correct miss-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming.
- inferiorhuman 3y ago
  because Boeings don’t normally autotrim Yeah they do. On the 737/757/767 they have a mach trim system to account for mach tuck. On the 737, at least, they also have a speed trim system to keep the plane under control at lower speeds when autopilot is off.
quench 3y ago
>unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place Air France seemed to manage ithttps://www.avweb.com/aviation-news/air-france-crew-fought-each-other-for-control-say-investigators/ https://www.avweb.com/aviation-news/air-france-crew-fought-e... Also glad to see that airbus are planning to put force feedback side-sticks in future.
- quietbritishjim 3y ago
  > Air France seemed to manage it [on a Boeing] Hence my "at the time" bracket. Since then, newer Boeing planes have actually removed the physical connection between the sticks! Absolutely bonkers decision given the background. (I put "at least" at the end of my bracket because I wasn't 100% sure I rememebered correctly.) But maybe there is a good reason - e.g. like a sibling comment suggested, if one gets stuck.
  - masklinn 3y ago
    AFAIK the 777 still has mechanically linked yokes. It has a breakout mechanism in case one of the controls gets jammed (allows freeing the other one), but it's not been removed.
  - inferiorhuman 3y ago
    As the sibling comment points out the 777 has mechanically linked yokes. The 787 does too. With the Air France go around, the pilots were pulling hard enough that the mechanical connection between the yokes was broken. Both pilots continued to provide contradictory inputs. On an Airbus this would trigger a "dual input" annunciator, and there's a "priority takeover" button that would lock out one set of controls. On the Boeing once the torque tube splits each yoke controls one side of the aircraft. The synchronization and feedback intuitively seem like a good idea, but the reality is that at the point where you need to notice that the other pilot is doing something wrong you're already up shit creek and you're no more likely to notice an increase in force required to move the yoke than you are an annunciator. Linked controls aren't a substitute for CRM.

gregsadetsky 3y ago

The tragic AF447 flight comes up somewhat regularly on the site — see this recent conversation [0]. [0] https://news.ycombinator.com/item?id=37089363 https://news.ycombinator.com/item?id=37089363

dredmorbius 3y ago
CFIT is a particularly spectacular form of failure. <https://en.wikipedia.org/wiki/Controlled_flight_into_terrain https://en.wikipedia.org/wiki/Controlled_flight_into_terrain>

MichaelZuo 3y ago

It's not something that can be changed on airbus cockpits, since the nature of side sticks makes them impossible to be mechanically linked, unless there was some very complex motor system built into each stick that provided force feedback equal in strength to a pilot tugging hard on it.

masklinn 3y ago
> unless there was some very complex motor system built into each stick that provided force feedback equal in strength to a pilot tugging hard on it It does not have to be “equal in strength to a pilot tugging hard on it” since there is normally no significant load applied by the stick to the hand (only the centering springs). So most every feedback should be noticeable. And force feedback is being deployed right now on commercial planes. The Irkut MC-21 was supposed to be the first airliner featuring them, but the invasion of ukraine and subsequent sanctions nixed that (as the provider of the sticks is the french company Ratier-Figeac). Gulfstream’s 7th gen (GVII) also have active sticks, provided by BAE.
- MichaelZuo 3y ago
  Yes, but then no one would consider the feedback to be the equivalent of a mechanically linked system, like what Boeing uses.
  - masklinn 3y ago
    Of course they would: the problem is that there is a lack of feedback when incompatible input is entered. Audio feedback was added since AF 447 but as well known sound is one of the first thing to be blanked out in high stress situations. Physical feedback provides a second stimulus, and one which does not get ignored as much. The planes are FBW, the side sticks have no mechanical linkage outside their control box, there is no cause for a pilot to input significant force on the stick, and thus most every feedback would be sensible. Unlike a 737, the pilots are not physically moving the control surfaces.
    - 3y ago

cesarb 3y ago

> unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place I don't know if it's true, but I recall reading somewhere that this physical connection is a breakable link, so if one of the controls gets stuck the other control can still be used to fly the airplane (after some application of strong force to break the connection).

f1shy 3y ago
Yes it is true. The force needed is pretty high.
immibis 3y ago
It also caused one accident, where both pilots thought the controls were jammed because the other pilot was pulling in the opposite direction. This is no better than averaging. At least Airbus gives an alarm.
- ImPostingOnHN 3y ago
  Which accident was that? Thanks!
  - immibis 3y ago
    Don't remember, sorry.
    - ImPostingOnHN 3y ago
      I couldn't find any evidence of it happening either, which makes sense, a system which gives feedback there's a problem intuitively seems better than one which doesn't.
      - inferiorhuman 3y ago
        a system which gives feedback there's a problem intuitively seems better than one which doesn't. Except that your intuition isn't always correct. Airbus throttle levers don't move on their own, Boeing throttle levers (at least pre-FBW) were mechanically linked to the control system and would move in response to computer inputs. Sounds safer, right? Look at the Sriwijaya Air 737 crash (among others). Even with the throttle levers showing wildly asymmetrical thrust, when the automation gave up the pilots didn't notice, didn't react properly, and crashed the plane.

masklinn 3y ago

> unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place, and you'd feel the other pilot fighting you. Note that it’s not quite that flagrant: because Boeings don’t normally autotrim (famously aside from the 737 MAX, whose MCAS was not documented and trained for — I think the more recent Boeings like 777 and 787 are FBW and do autotrim) it’s possible to fight your co-pilot while thinking you’re not trimmed, or even that you have excessive air load: > excessive air loads on the stabiliser may require effort by both pilots to correct miss-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming.

inferiorhuman 3y ago
because Boeings don’t normally autotrim Yeah they do. On the 737/757/767 they have a mach trim system to account for mach tuck. On the 737, at least, they also have a speed trim system to keep the plane under control at lower speeds when autopilot is off.

quench 3y ago

>unlike on a Boeing (at the time at least) where they're physically connected so you can't have contradictory inputs in the first place Air France seemed to manage ithttps://www.avweb.com/aviation-news/air-france-crew-fought-each-other-for-control-say-investigators/ https://www.avweb.com/aviation-news/air-france-crew-fought-e... Also glad to see that airbus are planning to put force feedback side-sticks in future.

quietbritishjim 3y ago
> Air France seemed to manage it [on a Boeing] Hence my "at the time" bracket. Since then, newer Boeing planes have actually removed the physical connection between the sticks! Absolutely bonkers decision given the background. (I put "at least" at the end of my bracket because I wasn't 100% sure I rememebered correctly.) But maybe there is a good reason - e.g. like a sibling comment suggested, if one gets stuck.
- masklinn 3y ago
  AFAIK the 777 still has mechanically linked yokes. It has a breakout mechanism in case one of the controls gets jammed (allows freeing the other one), but it's not been removed.
- inferiorhuman 3y ago
  As the sibling comment points out the 777 has mechanically linked yokes. The 787 does too. With the Air France go around, the pilots were pulling hard enough that the mechanical connection between the yokes was broken. Both pilots continued to provide contradictory inputs. On an Airbus this would trigger a "dual input" annunciator, and there's a "priority takeover" button that would lock out one set of controls. On the Boeing once the torque tube splits each yoke controls one side of the aircraft. The synchronization and feedback intuitively seem like a good idea, but the reality is that at the point where you need to notice that the other pilot is doing something wrong you're already up shit creek and you're no more likely to notice an increase in force required to move the yoke than you are an annunciator. Linked controls aren't a substitute for CRM.