Friday, June 12, 2009

Computer Piloting & Air France Crash

By William John Cox
June 12, 2009

How the Air France Flight 447’s Airbus A330 crashed into the Atlantic Ocean remains a mystery, but what is known is that Airbus’ heavy reliance on computerized piloting has a history of some bizarre or unexplained crashes when the technology failed, misread the circumstances, or complicated efforts by human pilots to react to an emergency.

Read on.
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2 comments:

Anonymous said...

Hi,

It was an interesting read.

Unfortunately I can't judge whether the description of the position that the "man" takes in the Airbus flight system "loop" is accurate. Apparently the position is only missing the Husky that keeps the man from touching the controls. A fairer description would be that the pilot "drives" the plane, telling it what to do, as opposed to "flying" the plane by setting its control surfaces etc.

It is really time again to raise questions about commercial FBW? I imagine that discussion was done to death back in the 80's. I also suppose there are weighty manuals at Airbus/EADS describing in detail the rationale of design and the risk analysis of the whole system, "man+computer+plane" and I do not expect them to be a shoddy job.

That being said, I well know that a computerized system of some complexity can fail in interesting and unexpected ways and is thus open to justified scrutiny. But then again, would a human fare better? Accident statistics will tell...

On to the inaccuracies:

"FBW: First developed by NASA to augment control of the space shuttle and high-performance military combat planes"

Well, FBW goes back far longer at least to the Apollo program (and in some sense to the X-15) when it became judicious to consider situations in which the on-board computer could either lighten the workload of the pilot or else take over tasks that the pilot would just be unable to accomplish - like stabilizing the ascent of a rocket into orbit (though the pilots were not too happy about that). On this subject, David Mindell's "Digital Apollo" can only be recommended.

The ABS paragraph is a red herring. It could well be that you can find the "experienced operator" who is able to outsmart ABS in keeping the vehicle aligned in some particular situation (but then, how does he outsmart it exactly?) Still, the vast majority of people are challenged by a shift gear alone. In the end, whether ABS is useful or an appropriate addition to the man-machine car system must be decided by checking whether statistically more accidents involve cars with ABS or without ABS.

The Comet also is a red herring. If planes crash due to metal fatigue, this has nothing to do with FBW or, in this case, powered controls - something the pilots apparently were not disliking - but with new and possibly surprising failures appearing in a new system - in this case aluminium skin subjected to repeated pressurization cycles. It also says nothing about European airplane design problems or quality control or anything.

Finally, we read "however, there have been substantial gains made in the development of spaceplanes – aircraft capable of orbiting the Earth and landing on runways – and the momentum should propel hyperspace travel forward into the future."

That would be just "space", not "hyperspace" I reckon. I am not currently aware of any commercial attempt to develop or put into use suborbital spaceplanes (which just hop out of the atmosphere, as opposed to orbital spaceplanes which need Space Shuttle speed and the attendant extra-expensive support infrastructure). The Ansari X Prize efforts do not really count.

I would bet that suborbital flight - to say nothing of orbital flight - will remain out of reach for a long time. When the time comes and these exist, automatics will certainly have reached pilot-equality level and be able to handle even "unforeseen situations" with acceptable ability (for some values of "acceptable"). Fancy a plane that decides by itself that the only way out of Dodge is to do a barrel roll? Why, it might happen.

Best regards.

-- Anonymous Stanislaw Lem Reader

Sat Jun 13, 06:12:00 PM 2009
Anonymous said...

"Pilot Chesley B. “Sully” Sullenberger III has become a national hero; however, there remains a question whether the Airbus flight control system unnecessarily shut down both engines, whereas a Boeing aircraft engines might have chewed up the birds and kept flying."

Both the Boeing and Airbus use the same engines and same engine control computers. It makes no difference. The engine decides if it can keep running, and that is decided by the Engine Manufactures control system. Not the aircraft manufactures control system.

Wed Jun 17, 01:49:00 PM 2009

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