Source: https://www.vanityfair.fr/actualites/articles/vol-af-447-rio...
I'm not sure what you mean by "throttle up". They were at full TOGA thrust.
Neither Bonin nor Robert, nor the third crew member (Marc
Dubois, the captain) who entered the cockpit 90 seconds
into the episode, recognized that the aircraft had stalled
despite multiple cues. In the confusion, Bonin
misinterpreted the situation as meaning that the plane was
flying too fast and actually reduced the thrust and moved
to apply the speedbrakes – the opposite of what was
required to recover from the stall. Robert overruled him
and attempted to take control, but Bonin continued to try
and fly the plane. He and Robert made simultaneous and
contradictory inputs, without realizing that they were
doing so. By the time the crew worked out what was going
on, there was insufficient altitude left to recover, and
AF447 crashed into the ocean, with the loss of all 228
passengers and crew.
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.
Page 28: The right-seat co-pilot Bonin says "j’ai l’impression qu’on a une vitesse de fou non qu’est-ce que vous en pensez ? "(I feel like we're speeding like crazy, what do you think?")
Page 31: Same co-pilot "mais je suis à fond à cabrer depuis tout à l’heure " (But I've pulling back completely for a while), and this while the cockpit is screaming "Dual Input" (so this means that the other pilot was inputting as well, thus "unbeknownst" in my original comment).
Same page, right after, the captain says, "non non non ne remonte plus là" (No, no, no, don't pull back any further".
If you read the entire transcript, it's clear that there was persistent confusion as to who was in control, despite the dual-input warnings. AF447 is widely considered to be a failure in CRM, and a failure to recognize that they were in an aerodynamic stall (again, despite the warnings).
They didn't trust the plane with the information it was providing, which is probably why they ignored these warnings.
Perhaps you didn't notice this, but immediately after the point in the transcript you refer to, there's an exchange between the pilots where they establish who's in control (see "vas-y tu as les commandes" at 2 h 13 min 46,0). There is no way to be sure, but it seems probable that this exchange was prompted by the dual input warnings.
>They didn't trust the plane with the information it was providing, which is probably why they ignored these warnings.
There is no indication that they ignored the dual input warnings.
Linking the control sticks doesn't magically resolve problems caused by a breakdown in cockpit discipline. If both pilots are going for the controls at the same time, you're going to have problems. The warning system seems to have done its job, insofar as it prompted the pilots to figure out who was in control.
As for the dual input thing, there are 6 instances of the the warning. We can't really know what the pilots were thinking, but I believe page 31, from when Bonin says, "je suis à fond à..."... and then Robert à "attends moi j’ai des j’ai des commandes moi hein" a little later, "alors donne moi les commandes à moi les commandes", and 4 warnings Dual Input between them (in the space of about a minute and a half)...
I think it's fair to say that it wasn't super clear who was in control.
I'll make no comments about which system is better since I have no direct experience of flying in such environments (have only piloted small aircraft with mirrored controls, but with clear "Commande à droite/gauche" to establish PF, with my instructor). But à priori, I would imagine both systems work fine if used well.