This report presents the findings of our investigation into the disappearance of Flight 305.The main findings were (1) that the airplane hit a severe thunderstorm, (2) that it stalled, and (3) that the co-pilot knew about the problem with the speed but couldn't communicate the problem to the pilot in time .The report recommends that all pitot tubes be inspected and replaced regularly when necessary, and that the airline should train all flight crew on how to communicate better during emergencies.