If they're mechanically linked, the captain would at least feel the first officer countering their inputs -- giving a prompt that they need to communicate their intentions more clearly!
I'll defer to a pilot to say whether they are mechanically linked -- it sounds like they are on Boeing aircraft but possibly not on Airbus?
They're mechanically linked on Boeing aircraft. On the 757, and I believe the rest, the mechanical link has a detent. With enough force, the pilot can move it out of the detent and move the controls independently of the copilot. The reason for this is if one side or the other is jammed, the pilot can still fly it.
No, the captain would not, because only one pilot has their hands on the controls in any given instance (with the possible exception of rotation at takeoff).
It's quite clear that wasn't sufficient. "Brief moments" during critical points in an emergency can matter enormously. From the recorder transcript:
> As the plane approaches 10,000 feet, Robert tries to take back the controls, and pushes forward on the stick, but the plane is in "dual input" mode, and so the system averages his inputs with those of Bonin, who continues to pull back. The nose remains high.
02:13:40 (Bonin) Mais je suis à fond à cabrer depuis tout à l'heure!
But I've had the stick back the whole time!
02:13:42 (Captain) Non, non, non... Ne remonte pas... non, non.
No, no, no... Don't climb... no, no.
02:13:43 (Robert) Alors descends... Alors, donne-moi les commandes... À moi les commandes!
Descend, then... Give me the controls... Give me the controls!
> Bonin yields the controls, and Robert finally puts the nose down. The plane begins to regain speed. But it is still descending at a precipitous angle. As they near 2000 feet, the aircraft's sensors detect the fast-approaching surface and trigger a new alarm. There is no time left to build up speed by pushing the plane's nose forward into a dive. At any rate, without warning his colleagues, Bonin once again takes back the controls and pulls his side stick all the way back.
See in particular 2 h 13 min 39,7 and 2 h 13 min 40,6. Both of the pilots at the controls thought that they needed to climb. The captain realizes the mistake, but he's not at the controls, so linked sticks would have made zero difference to his perception of the situation. The accident report concludes that the stall was probably unrecoverable by this point anyway.
The section I'm citing is right there on page 31 of your second link. See 2 h 13 min 39,7. More dual input at 2 h 14 min 03,2. Crash at 2 h 14 min 28,4.
That is the point where both pilots at the controls still think that they need to climb. The captain, who realizes the mistake, is not at the controls, so whether or not the side sticks were linked would have made no difference to his perception of the situation.
The official report does not identify the side sticks as a factor in the accident.
If you think you can do a better job of identifying the cause of the accident than the professionals who investigated it, you should explain clearly why.
With regard to dual input, it's clear from the transcript that the pilots noticed the dual input alarms.
I'll defer to a pilot to say whether they are mechanically linked -- it sounds like they are on Boeing aircraft but possibly not on Airbus?
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