The A320 that crashed into the mediteranian was XL 888T on a check flight. The aircraft's lease was up and XL was in the process of returning it to its owner.
There were three problems that led to the crash:
1. the maintenance crew had washed the plane with a high-pressure hose, thus pushing water into the AoA sensors,
2. the crew did flight tests without authorization and at a dangerously low altitude and
3. the crew did not realize that their plan correctly identified the problem with the AoA sensors and fell back giving the pilots manual control over everything, including crucially the trim.
Had either the PF or the PM read the message on the annunciator and understood it (the CVR indicates that they didn't even read it) they could have trimmed the nose down and the plane would have remained entirely stable.
Also, the crew might have monitored the IAS and realized that the stall protection had not kicked in, long before the speed would have dropped so low.
The chain of problems that led to AF447's crash were: 1. flying through a thunderstorm,
2. pitot tubes freezing,
3. the PF not following procedure in the case of frozen pitot tubes and instead pulling up and
4. said pilot keeping his sidestick pulled back thoughout the stall and drop out of the sky DESPITE the more experienced PM having said several times that he was taking control and that the nose had to be brought down. (In fact FO Bonin did only announce that he was still pulling back on the stick at FL040, at which point it was far to late to do anything.)
The incident this thread is supposedly about was solved by pressing two buttons on the overhead and there was never any real danger to anyone.
Really, people should stop with the blind the hysteria. FBW has saved lots of people's lives and many disasters would not have happened, had the plane had Airbus' system.