[huntero]

It's interesting that First Officer Bonin is able to doom the plane by continuing to hold back on his joystick, even when that action isn't having positive results. Had the other first officer pushed his joystick forward, would the plane begin to dive? I assume that one joystick has precedence over the other...

It seems dangerous to have two joysticks, both capable of controlling the plane, that have no physical or simulated physical link. It means that one pilot could be attempting to control the plane and his actions will have no effect whatsoever if the other seat is panicking (as in this case).

Anyone have any insight into this?

[jonnycowboy]

Airbus' have priority override button which will allow the pilot not flying (PNF) to take command of the aircraft. In hydraulic or "direct" flight controls, both sticks move at the same rate, you need to be stronger than the other pilot. Normally the autopilot and flight control system would have the authority to override the pilot actions (common on A320 etc.) but not all planes have that feature.

In addtion, if the autopilot or flight control system goes from a fully 'in the loop' mode to a 'direct mode' where input=output (the transition possibly being caused by faulty airpseed sensors in this case), the automatic flight control mode has no more authority to interrupt pilot command.

In situations like you describe where two 'free' (no force feedback in relation to control surface force) joystics are used, it is better to have a 'pilot in control' switch otherwise you could get situations where an inexperienced pilot would panic and force his joystick to an unsafe position, overriding the more experienced pilot.

See the following link for more info: http://msquair.wordpress.com/2011/09/16/pilots-in-the-loop-a...

[themonk]

Should not one pilot say "I Got Her" and tell other pilot that you do nothing, I will take care of it.

[vacri]

That happened in the main article, but the pilot in error takes control back shortly after.

[leoedin]

In all cockpits, there is usually a strongly defined system of who is currently in control. At one point you can see this happening - one of the pilots declares "I have control". In normal flying conditions, any time flight control passes over between pilots there should be a declaration along those lines. However, the reactions of the pilots in this situation don't seem to be entirely in line with what they should have been doing, which is a major contributing cause to the crash.

[jeffbarr]

According to the article, the input from the two joysticks is averaged.

[greiskul]

Which raises a very good question, when would you ever want that joystick behaviour?

[fr0sty]

This is a fantastic question. I can think of no situation where this behavior would be desireable, but then again IANAP

[flyingkiwi]

I am a pilot (a small one but instrument rated) - there's no time EVER that you want that, and I am shocked the Airbus does not have a warning that says DUAL INPUT BEING RECEIVED. At the very least, it should give priority to the left seat controls.

Was really shocked to read the article.

[nchaimov]

It does: there's an audible warning that says the words "DUAL INPUT"

The English translation of the BEA's third interim report on the flight is available here: http://www.bea.aero/docspa/2009/f-cp090601e3.en/pdf/f-cp0906...

It includes the full CVR transcript at the end, which shows that the dual input alarm activated five times.

[tankenmate]

I think that part of the problem here is that the plane is so far out of trim and CRM has gone completely out of the window that psychologically at least the mental workload on the junior pilot has caused him to "freeze".

Far worse, imaging a situation where one of the control inputs fails; i.e. constantly produces nose up input. Can one of the inputs be suspended / turned off?

[tcarnell]

... so if there was a noise (intercom, radio, talking etc) and you didn't hear the announcement, that's it ,game over.

[mikeash]

IAAP (not commercial) and that sounds like an awful way to do things. An important aspect of cockpit resource management is to know who is controlling the airplanes, and part of that is always positively verbally transferring control, with confirmation. "I have the plane." "You have the plane." There is no situation where you want two people to both have input at the same time.

[flyingkiwi]

IIRC, that was lesson 1, minute 2 (right after take-off). The previous commenter who said that wouldn't think to ask because it is akin to asking 'is the computer plugged in' is probably right (though the captain should have noticed it when he was observing).

Serious design flaw, and tragic human error with devastating results. :(

[mikeash]

I'm actually mildly surprised that it waited until you were in the air. I always brief that before takeoff whenever I take another pilot along. But yes, very basic stuff in any case, and amazing that they were not following this standard procedure.

[crikli]

I'm a pilot and that seems insane.

[Too]

I guess it could be a cheap workaround to always get smooth transitions when changing pilot. Imagine if one pilot holds full left and the other full right and you press a "switch now!"-button. You would need some kind of transition-period of maybe a second to avoid jerk which could be confusing for the pilot to not know when he has full control and when he is in transition.

[andrewmccall]

This is likely the reason, and probably not just as a cheap work around, in most day to day situations it's probably the desired effect since both sticks are independent and don't move in reaction to the other.

[delackner]

Actually if both sticks are actually linked, the person taking over will find his stick already full-left, and have to actually pull it over to the right as part of "taking over". Such simplicity and it would result in none of this insanity.

[tcarnell]

good point - but I think a 'dual input' mode is the wrong solution to that problem.

[omegant]

Simply is the cheapest when you want to go all digital.

[weaksauce]

True. But, how would you want to handle the situation of two equally competent(at least in the eyes of the employer) co-pilots vying for control? should it always go to one? always go to the other? have a switch controlled? controlled by whom? not easy questions if you ask me.

edit: I actually can't think of a good way to do that other than have a manual switch on the console that would switch between the two controls. anything else seems amazingly bad.

[joshAg]

perhaps have the plane decide which input seems more rational, then announce who has control.

[einhverfr]

Sounds like a great way to further mess up an emergency by making it harder for people to figure out the impacts of their actions on the situation.