WASHINGTON, D.C. -

Federal accident investigators say "mismanagement" by the pilots of Asiana Flight 214, including confusion over whether one of the airliner's key controls was maintaining airspeed, caused the plane to crash while landing in San Francisco last year.

The National Transportation Safety Board also said Tuesday that the complexity of the Boeing 777's autothrottle, as well as materials provided by the aircraft maker that failed to make clear when controls don't automatically maintain speed, contributed to the accident.

The South Korea-based airline's pilot training also was faulted.

The plane, with 307 people on board, was too low and too slow during the landing attempt. Its tail struck a seawall and was ripped off. The rest of plane went spinning and sliding down the runway. Three passengers were killed and more than 200 injured.