I heard that for Boeing and Airbus aircraft, the pilot's and copilot's brake pedals are mechanically linked, is that true?
Why did they make that design decision? What's the advantage? Do all kinds of passenger aircraft have the same design?
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$\begingroup$ More like hydraulically linked? What else can you do so that they can both operate the brake? Use full electric control? Two independent brake systems? $\endgroup$ – user3528438 Jun 28 '17 at 13:54
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$\begingroup$ @user3528438 The planes are fly-by-wire so they certainly dont need a physical link between the controls. For a specific example, the sidesticks used to control Airbus aircraft aren't physically linked, which was a factor in the crash of Air France flight 447. $\endgroup$ – David Richerby Jun 29 '17 at 9:45
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It is cost effective for one. With an unlinked system, you now need to resolve disagreement between inputs some other way. Software has its own challenges. It's also instant, non-verbal communication between captain and first officer. A pedal moves and the other's pedal has already moved. No confusion or pilot effort to communicate it.
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Yes they are always mechanically linked. It is the best way of having two persons operate one device, since both can feel what is happening without having to look at what the other is doing - they cannot see each others' feet anyway.
The force sensors in our body are quite accurate and can intuitively interpret if someone is helping or opposing in actuating the task at hand, because this is how things work in nature and that is what our bodies are built for. In nature, an item moves as a result of the sum of all forces. So best to build a set of brake callipers such that it is deflected as a result of the sum of forces of the two pilots, in such a way that each can feel what the other is doing.
Mechanically link the captain and F/O brake pedals and:
- When one pilot deflects the brake pedal fully, the other one can feel the pedal being at the travel stop and knows that further pushing has no effect
- Each pilot feels the brake pedal deflect as a result of the others action. If #1. wants to add to the action of #2, #2 can feel that instantly.
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$\begingroup$ Is this true for Airbus too? Seeing as their sidesticks are not mechanically linked. $\endgroup$ – Sanchises Jun 29 '17 at 8:53
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$\begingroup$ I assume so but cannot find confirmation. The A320 simulator Level D flight controls I worked on had mechanically interconnected rudder pedals, and it seems logical that the brake pedals are mechanically interconnected as well. I'll check next time I'm in the sim. $\endgroup$ – Koyovis Jun 29 '17 at 14:36
