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Comment by ejdyksen | Hacker News Reader

The AF447 crash was an example of exactly why the Airbus side stick model is flawed compared to the Boeing yoke.

In AF447, one of the pilots had a nose up input held during a stall. Because the other pilots couldn't see his stick, they weren't aware of his inputs. Also, at certain times, the other pilot was giving contradictory (nose down) inputs to the aircraft. This input was averaged (read: canceled) with the other pilot's nose up input.

The side stick has two problems: 1) Lack of awareness of what inputs are being given to the plane by other pilots in the flight deck. 2) The computer has to make decisions about how to resolve contradictory inputs.

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But you know that nowadays even Boeing is using fly-by-wire? So the only difference is the input device which more a question of convenience or personal preferances. basically it all comes down to training, experience and system knowledge. The make of your aircraft is secondary.

by the way, the A330 has a pretty good safety record. We shouldn't judge one approach based on one single incident no matter how severe.

And even it came ultimately down to a pilot error, in order to make plane crash it takes a whole chain of events. In AF447's case the pilots reaction was the last straw, yoke or side stick.

Forget the fly-by-wire, the crucial difference here is that the input devices on the Boeing craft move together. If the AF447 crew had this feedback the accident most likely would not have happened.

Hard to tell afterwards. A botched-up situatation is just that, botched-up. During the AF447 accident so much things went wrong that's almost impossible to single out one that could have prevented it.

Being in aerospace, I slowly get fed up by all this "My airplane is better than yours and that would have happened if yours had what mine has" discussions. I know it is kind of OT right now and that it's HN here and not a pilots forum but I consider it just childish. It's the final report of the authorities that counts, nothing else.

Enough said on AF447, I think the 787 is one pretty plane. What I'm cusious to see is whos bet is right, Boeings' on more point to point flights or Airbus' on the more traditional hub-spoke structure. Just hope Boeing is getting the Dreamliner industrialized and built with less pain than Airbus had on the A380. It slowly becomes a shame how much problems aerospace companies have with that in the last decade.

As a controls and human-factors engineer, I think the subject is highly relevant and very interesting.

There is a large and distinct difference in the flight control mechanism of these two airplanes. It's been discussed over and over, and the transcript of the voice recorder and control logs show there there was a distinct discrepancy happening in the cockpit while the plane was going down:

"As the plane approaches 10,000 feet, Robert tries to take back the controls, and pushes forward on the stick, but the plane is in "dual input" mode, and so the system averages his inputs with those of Bonin, who continues to pull back. The nose remains high." [1]

So, being in aerospace, is this subject annoying or something that is normally not discussed?

[1] http://www.popularmechanics.com/technology/aviation/crashes/...

I'm not a avionics engineer. But at least under my collegues this is discussed. Unfortunately with a clear preference of the Airbus approach with some "conaisseurs" in between baseing their preferance of the Boeing yoke on aviation tradition. But I guess that's normal for the EADS.

Maybe the controlls were a factor in that crash, but for me it's just two different philosophies. Only my personal opinion and I'm no position to judge that.

Yes. The side-sticks not moving in sympathy is a hindrance to monitoring the handling pilot.

The AF447 inputs were averaged.

I stand corrected.

Sidestick priority logic — When only one pilot operates the sidestick his demand is sent to the computers. — When the other pilot operates his sidestick in the same or opposite direction both pilots inputs are algebraically added. The addition is limited to single stick maximum deflection. Note : In the event of simultaneous input on both sidesticks (2° deflection off the neutral position in any direction) the two green SIDE STICK PRIORITY lights on the glareshield come on. In addition on A330E, the "DUAL INPUT" voice message activates). A pilot can deactivate the other stick and take full control by pressing and keeping pressed his takeover pushbutton. For latching the priority condition, it is recommended to press the takeover pushbutton for more than 40 seconds. The takeover pushbutton can then be released without losing priority. However, at any time, a deactivated stick can be reactivated by momentarily pressing either takeover pushbutton. If both pilots press their takeover push buttons, the last pilot to press will get the priority. Note : If an autopilot is engaged, the first action on a take over pushbutton will disengage it.

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