Air France flight 447 had too many alarms go off, and the pilots could not cope. Turns out that getting mid-flight problem diagnostics right is a really difficult problem.
Now, in the Air France flight, part of the problem was the system trying harder than it should have: it would have sufficed to alert the pilots to the lack of air speed indication and let them figure out what to do, but instead the computers cascade alarm after alarm.
You can see the problem: various pieces of the system were engineered separately, and there was no single system that could have suppressed the downstream alarms so that the pilots could focus on first on understanding the first alarm. Then again, that too might not have been a good design: perhaps a stall alarm should take precedence, say, over a frozen pitot alarm.
There is a caveat to the Air France 447 crash, that the pilots apparently relied too heavily on the autopilot. When the alarms came on mid-flight, neither pilot was familiar with the current state of the plane and found it more difficult to diagnose the problems. One of the recommendations to come out of that crash was that pilots on long flights should occasionally switch back to manual control to keep themselves synced with the aircraft's state.
Now, in the Air France flight, part of the problem was the system trying harder than it should have: it would have sufficed to alert the pilots to the lack of air speed indication and let them figure out what to do, but instead the computers cascade alarm after alarm.
You can see the problem: various pieces of the system were engineered separately, and there was no single system that could have suppressed the downstream alarms so that the pilots could focus on first on understanding the first alarm. Then again, that too might not have been a good design: perhaps a stall alarm should take precedence, say, over a frozen pitot alarm.