On AF447 all three of the airspeed probes iced up for 40 seconds, prompting the flight computers to disconnect autopilot and autothrottle and clearly announce t

On AF447 all three of the airspeed probes iced up for 40 seconds, prompting the flight computers to disconnect autopilot and autothrottle and clearly announce to the crew that air data was unreliable and that the normal protection against stalling was suspended. The pilots immediately understood the problem, however for various reasons made a series of bad decisions which resulted in the crash. Tragically there was no need for the pilots to take any urgent action - by design the plane continued in stable flight when the air data was lost. On the 737MAX crashes the single angle of attack indicator being used as input to the MCAS malfunctioned and in response the system set about repeatedly forcing the plane into a dive with no clear indication of why this was happening. Compounding this was the utter lack of training on the MCAS system, which wasn't even mentioned in the pilot manual or IPad-based training that was also used by US airlines. There's a world of difference between these accidents.