Air France 447: The ‘Coffin Corner’ and a ‘Mesoscale’ Maw

Assuming that the autopilot and fly-by-wire systems were somehow compromized, a full stall in the "Coffin Corner" (Q-corner) would be a very, very serious condition. A stall causes the nose to drop and speed to accumulate. Since the difference between the stalling speed and the never-exceed speed is so small at the altitude in question, this accumulation of speed could easily cause the plane to exceed its critical Mach number, causing supersonic shockwaves around certain parts of the airfoil. In planes not designed for supersonic flight, these shockwaves will eventually cripple the effect of the control surfaces. If the plane is in a nose-down position when it looses effect on its elevator rudder, the plane will overspeed and eventually suffer structural failure (essentially meaning the loss of some critical part) due to flutter (resonance in parts of the airframe) or aerodynamic stresses.

A stall during normal flight conditions doesn't have to be a serious problem, but these weren't normal flight conditions. And the information that we have suggests that certain Airbus models have had problems with their pitot (speed measurement) systems in icing conditions, leading to erroneous speed readouts. The fly-by-wire system, which prevents the pilot from flying the aircraft into stall or overspeed, cannot function correctly without a correct speed measurement. And as I have detailed, a proper stall might be enough to doom the airplane.

And when I got my CS degree we specifically studied accidents where bad software in medical devices killed people. I recall an X-ray machine where the hardware was upgraded and a bunch of software assumptions about when the fuses would blow became wrong. That ended up killing people.

And as someone who has written software for medical instruments I can tell you unit test coverage is part of the contracts we sign.

The coffin corner only played a small part in the accident but that's how accidents always happen. It's always several small things that go wrong together.

A safe airline would not flaunt its safety record, but it's safety practice. Not flying the coffin corner would remove that one part that can go wrong from any future accident scenario.

The safe airline having an accident would not automatically bankrupt it, every other airline has had accident and this one would continue with its safer then average practices.

However, I agree with you this will never happen because as you say the airlines are a crap commodity business. Even Warren Buffet has mentioned how bad a business airlines are for investors.

That's why even though I consider myself a libertarian I want a government mandate to stay out of the coffin corner.

We already have much more complex and difficult to enforce regulations on airlines, this one is simple and would be easy to enforce as we already track all planes on rader closely all of the time.