The Airbus A330 has one of the most sophisticated automated piloting systems in the airline industry, but the 2009 crash of Air France Flight 447 has some experts saying that the pilots weren't adequately trained to handle the plane in an emergency situation, and that the plane's stall alarm system may have added to the crew's confusion and contributed to the disaster.

The crash, which killed all 228 passengers and crew on board, is considered one of the worst -- and most mysterious -- aviation disasters in modern history. One theory for what caused that Airbus A330 to go down is that the two co-pilots, led by 58-year-old Captain Marc Dubois, were not properly trained and depended too heavily on the plane's autopilot system. That system disconnected at high-altitude when a speed sensor, called a pitot tube, froze over, sending inconsistent readings to the plane's computers.