Conflicting inputs are handled by averaging and an audible "DUAL INPUT" cockpit warning. In the case of AF447, the co-pilot used his "Priority Takeover" button which meant only his control inputs were in effect.

The pilot doesn't get a notice in that case? Or was he just like "k what ever"

There is both a visual and aural indicator. That being said, nobody (except Bonin) knew that the PF had his stick completely back until it was too late.

You can see more here: https://safetyfirst.airbus.com/app/themes/mh_newsdesk/docume...

That stuff is really interesting, I've been digging through random reports, documents and manuals for two hours now.

Yeah, it really is. If you haven't already, check out the full BEA report - it's incredibly comprehensive and leads to lots of "jumping off" points for further research.

https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp09060...

The plane announces "priority left/right" and the pilot whose input is being ignored gets an indicator on their display.

>And unfortunately the Airbus takes the average of both pilot inputs

Really? That's the best way to handle that?

From what I read, it's a case of "can't do it the right way originally because of patents/legal/whatever; can't change it to the right way ever since because then every airbus pilot would need to requalify, every book rewritten, etc ...". Sounds like a terrible case of rotten legacy support.

A dual input alarm sounds when that happens.

The pilots should never both be trying to apply control inputs at once. There isn't really a good way of handling the situation where the pilots are not communicating and are trying to make conflicting control inputs.

Since I read that Popular Mechanics article, I think the exact same thing every time I board an Airbus plane.

Airbus has since updated its flight control feedback systems

Source for this?

I may be mistaken; I had thought I had read that Airbus had acted, but on checking up, I think not in ways which would make my brief implication useful.

Iirc the problem was an iced pito tube that gave unreliable airspeed coupled with operating in a different reality (mode of flight control per airbus) coupled with differing inputs from both pilots coupled with the fact that the stall warning was disengaged below a certain airspeed. All too often these crashes are not one single cause but a series of unfortunate events.

After I read about that I was nervous flying on Airbus for a long time. My understanding is that on Boeing the two yokes are linked so it would be impossible for one pilot to nose up without the other having his yoke move too.

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

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.

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.

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.

>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=...

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

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-cp09060...). The transcript is in an appendix: 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.

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.

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

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.

At 2h 10m the PNF (copilot in the left seat) warns the guy on the right about speed and says he needs to go back down. I believe that this is where the issue is, where he doesn't realise that the guy on teh right is still trying to climb. I think this is something I also read in the article, and it's good to see it in the logs (thanks for posting them)