6 ms·

So it becomes a power struggle and assuming roughly equal strength of both pilots, we are still averaging ...

sokoloff 8y ago
If that were the only factor, yes. The mechanical linkage though can help each pilot understand and discuss the actual inputs the plane is receiving, as well as being consistent with all the aircraft that they flew in primary civilian training.
refurb 8y ago
Yes, but at least that gives a signal to each pilot what the other is doing. It wasn’t until a few minutes before Air France’s crashed that the pilot realized what the copilot was doing.
- foldr 8y ago
  >It wasn’t until a few minutes before Air France’s crashed that the pilot realized what the copilot was doing. This is not true. See e.g. http://www.airliners.net/forum/viewtopic.php?t=772033&start=50#p11139241 http://www.airliners.net/forum/viewtopic.php?t=772033&start=...
  - refurb 8y ago
    2 minutes between captain returning to cockpit before he realizes the problem.[1] 02:11:43 (Captain) What the hell are you doing? [captain returns to cockpit] 02:13:40 (Bonin) But I've had the stick back the whole time! [At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself.] 02:14:29 - recording stops [1]https://www.tailstrike.com/010609.html https://www.tailstrike.com/010609.html
    - foldr 8y ago
      These are all descendants of the original popular mechanics article, which I don't think is a reliable source. The actual accident report is available to look at now (https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp09060...). The transcript is in an appendix: https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01.en.pdf https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01... Note that at the point of the transcript you're referencing, the captain was in the cockpit but not seated at the controls. It therefore would make no difference to his awareness of the situation whether or not the control sticks were linked, as he wasn't holding either of the sticks. Unlike the captain, the PNF and PF (who were seated at the controls) both seem to have thought that they needed to climb. See 2 h 13 min 39,7 and 2 h 13 min 40,6.
      - refurb 8y ago
        Of course the official accident report is a better source, but I’m not arguing linked controls would have helped. Just that it took the captain a few minutes to grasp the situation.
      - richardhod 8y ago
        The senior copilot was in the other seat, and the problem was that the unlinked controls meant that the senior co-pilot did not know during the previous 10 minutes what the junior Copilot Bonin, who had the controls, was doing, and that his (senior copilot) input to put the nose down was doing nothing
        foldr 8y ago
        As I said: Unlike the captain, the PNF and PF (who were seated at the controls) both seem to have thought that they needed to climb. See 2 h 13 min 39,7 and 2 h 13 min 40,6. There's also evidence from the rest of the transcript that the pilots at the controls were perfectly capable of observing (or inferring) which inputs were being made. I think there's an underling misconception here that an Airbus sidestack has a "position" akin to the position of the yoke of a plane with fully manual controls. An Airbus is flown with the sidestick remaining in its central position 99% of the time. To climb, for example, the pilot makes a short backward movement and then lets the stick return to its neutral position. The flight control software will maintain the specified climb until another stick input is made. For this reason, stick inputs tell you very little. If, for example, you see the PF push the stick forward, that doesn't necessarily mean that the plane's being put into a dive. The PF might just be reducing the rate of climb. You'd have to keep track of the complete history of stick inputs to know what was going on. On top of that, as only one pilot has their hands on the stick at any given time, for the PNF to visually observe brief movements of their own sidestick would hardly be any easier for them than just looking at the sidestick of the PF, who's right next to them.
thedrbrian 8y ago
If there’s a 40lb(iirc) difference in force inputs the rod linking the two columns breaks, at which point you should figure out what you’re doing.

If that were the only factor, yes. The mechanical linkage though can help each pilot understand and discuss the actual inputs the plane is receiving, as well as being consistent with all the aircraft that they flew in primary civilian training.

refurb 8y ago

Yes, but at least that gives a signal to each pilot what the other is doing. It wasn’t until a few minutes before Air France’s crashed that the pilot realized what the copilot was doing.

foldr 8y ago
>It wasn’t until a few minutes before Air France’s crashed that the pilot realized what the copilot was doing. This is not true. See e.g. http://www.airliners.net/forum/viewtopic.php?t=772033&start=50#p11139241 http://www.airliners.net/forum/viewtopic.php?t=772033&start=...
- refurb 8y ago
  2 minutes between captain returning to cockpit before he realizes the problem.[1] 02:11:43 (Captain) What the hell are you doing? [captain returns to cockpit] 02:13:40 (Bonin) But I've had the stick back the whole time! [At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself.] 02:14:29 - recording stops [1]https://www.tailstrike.com/010609.html https://www.tailstrike.com/010609.html
  - foldr 8y ago
    These are all descendants of the original popular mechanics article, which I don't think is a reliable source. The actual accident report is available to look at now (https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp09060...). The transcript is in an appendix: https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01.en.pdf https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01... Note that at the point of the transcript you're referencing, the captain was in the cockpit but not seated at the controls. It therefore would make no difference to his awareness of the situation whether or not the control sticks were linked, as he wasn't holding either of the sticks. Unlike the captain, the PNF and PF (who were seated at the controls) both seem to have thought that they needed to climb. See 2 h 13 min 39,7 and 2 h 13 min 40,6.
    - refurb 8y ago
      Of course the official accident report is a better source, but I’m not arguing linked controls would have helped. Just that it took the captain a few minutes to grasp the situation.
    - richardhod 8y ago
      The senior copilot was in the other seat, and the problem was that the unlinked controls meant that the senior co-pilot did not know during the previous 10 minutes what the junior Copilot Bonin, who had the controls, was doing, and that his (senior copilot) input to put the nose down was doing nothing
      - foldr 8y ago
        As I said: Unlike the captain, the PNF and PF (who were seated at the controls) both seem to have thought that they needed to climb. See 2 h 13 min 39,7 and 2 h 13 min 40,6. There's also evidence from the rest of the transcript that the pilots at the controls were perfectly capable of observing (or inferring) which inputs were being made. I think there's an underling misconception here that an Airbus sidestack has a "position" akin to the position of the yoke of a plane with fully manual controls. An Airbus is flown with the sidestick remaining in its central position 99% of the time. To climb, for example, the pilot makes a short backward movement and then lets the stick return to its neutral position. The flight control software will maintain the specified climb until another stick input is made. For this reason, stick inputs tell you very little. If, for example, you see the PF push the stick forward, that doesn't necessarily mean that the plane's being put into a dive. The PF might just be reducing the rate of climb. You'd have to keep track of the complete history of stick inputs to know what was going on. On top of that, as only one pilot has their hands on the stick at any given time, for the PNF to visually observe brief movements of their own sidestick would hardly be any easier for them than just looking at the sidestick of the PF, who's right next to them.

thedrbrian 8y ago

If there’s a 40lb(iirc) difference in force inputs the rod linking the two columns breaks, at which point you should figure out what you’re doing.