AF447 was flying in "alternate law" with limited (or maybe no) automation capability due to iced over airspeed pitot tubes. The aircraft did not know its speed

AF447 was flying in "alternate law" with limited (or maybe no) automation capability due to iced over airspeed pitot tubes. The aircraft did not know its speed and could not fly itself, or offer the anti-stall measures that would have normally prevented the confused pilot from stalling the flight from ~40k feet into the ocean.