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by lbourdages 881 days ago
Is there really an alternative?

Say one pilot loses consciousness, the other one has to extract them from their seat before they can fly the airplane. That's no easy task - humans are surprisingly heavy once they pass out.

4 comments

Airbus has had a Priority Takeover button, from the start, I assume Boeing also has something like that. Its primary use case is exactly what you’re talking about, although it also disables autopilot so it’s a good way to ensure you have manual input in case you need to react quickly.

Airbus has a dual input alert, apparently Boeing doesn’t, and didn’t add it after this incident, blows my mind. Still they’re far from perfect, stress deafness is absolutely a thing.

Active sticks (force feedback) are finally making it into commercial cockpits, they’ve been deployed in business jets, and the Irkut MC-21 was supposed to be the first implementation in an airliner (as it’s french-made, that’s been sunk by the Russian invasion of Ukraine and subsequent economic blockade).

This means hopefully active stick swill make it into big two airframes eventually. I assume there’s some redesign work ongoing as it likely requires additional power and data connection, AFAIK currently the sticks (Airbus’s anyway) are just centered and resisting via springs, I don’t think there’s any data fed back into the sticks.

> Airbus (surprisingly I think) didn’t have any sort of dual input alert

They did (and I think from the start, because unlike on Boeing's controls which are mechanically linked, there's no easy way of knowing the other pilot is inputting). From the wikipedia article of the crash:

> The inputs cancelled each other out and triggered an audible "dual input" warning.

https://en.wikipedia.org/wiki/Air_France_Flight_447

It's just that, as has been seen on many crashes, hearing is one of the first senses that disappears under heavy stress.

Quite incredible that the aviation industry haven't introduces sticks with force-feedback despite video game industry having them for about 30 years.

Probably because it's a patent lawsuit minefield.

Active sticks have been in development for decades. They’re getting deployed on civilian crafts these days e.g. Gulf Stream’s top of the lines jets (though retrofitting them on existing planes is likely a ways away still).

I would assume the issues are / were around reliability, failure modes, certification and training rather than patents.

Boeings use mechanical yokes and not sticks. They have force feedback by design.
The force feedback is applied by the "feel computer". On the 757 it's a hydraulic device designed to apply forces to the control column simulating the forces on the control surfaces.
I'm talking about feedback as it pertains to dual-input, which was what was being discussed above.
It's a different implementation of the same thing.
These are mechanically linked controls. Literally the force of the other pilot is directly felt and observed.

What force feedback in addition would you have in mind?

They have vibration in case of imminent stall: https://en.wikipedia.org/wiki/Stick_shaker
Active sidesticks have been around for a few years now:

https://www.youtube.com/watch?v=3sXXx8rgeeE

Three pilots with a voting algo, obviously. Or, maybe, a supreme court of nine pilots all constantly and continuously in search of perfect aerodynamic justice. Ah hell, just let ChatGPT fly the damn plane.

Edit: I've got it! We'll have a single pilot but they'll be based on a Rust rewrite of ChatGPT running on RISC-V.

2 chatgpt instances controlling the dual inputs would be funny
By "dual input system" I was referring to the fact that both pilots can apply input into their sticks or trim wheels simultaneously resulting into inputs cancelling each other out or de-synchronizing.
Agreed, that seems like a really bad design. At the very least there should be an alert whenever the system detects that both pilots are touching the controls.
Hm, cannot you just have a tree-way switch determining the active control (both, A only, B only)?