Air France Flight 447: The Paradox of ‘Simplicity’

Yeah, I should have made it clear that I was talking about autopilot. I have read other stories about the disaster that toyed with the idea that the Airbus autopilot cannot be overriden, and that the computers will always decide whats best for the plane.

For example, this statement from his article is misleading:

The computers are programmed with some strict rules (in fact, Airbus calls them “Laws”) designed to assess the human commands from the flight deck – and veto them if they would put the plane in harm’s way. Point the nose too high or too low – or bank to steeply and the computer will correct your bad airmanship. Who’s in charge here?

I didn't get that from the article. From what I understood, the point he was making was that the AP systematically relinquishes control of the plane as conditions deteroriate. By the time human pilots get hold of the plane, the conditions are for too difficult for them to handle. My issue with the article is the implications he makes. He compares the Boeing to the Airbus and then talks about the philosophy behind the Airbus. As I replied to sweetdreams, his statements about the plane (eg. Who's in charge here?) are misleading. It's as if he's saying that pilots are in full control of Boeing, but not in an Airbus.

You're correct in that being in the "coffin corner" is not dangerous in itself. In straight-and-level flight, if you go any faster, the extra drag will slow you down. If you reduce your thrust from your engines, you will slow down and lose altitude.

The problem comes about if you enter into any unusual attitudes, which is certainly possible in severe turbulence. The most important part would be a safe recovery to straight and level flight. An unusual attitude can put you in a situation where you overspeed the aircraft (e.g. nosedive). Above the maneuvering speed of the aircraft, you must be very careful to regain control without overstressing the airframe.[1] If your speed sensor(s) are giving you or the autopilot faulty readings, it would be very difficult to know the safest way to regain control of the aircraft after being put into an unusual attitude due to turbulence.

[1] American Airlines Flight 587 crash (NY, 2001) taught us that even below the manuevering speed of the aircraft, the airframe can be overstressed due to dynamic loads from pilot control inputs.