Pilot error and over-reliance on automated systems have been blamed by the National Transportation Safety Board for an Asiana Airlines crash in San Francisco last July.

The NTSB said the pilots of Flight 214 made 20 or 30 errors in the final 14 miles of approach.

The landing was too low; too slow.The co-pilot thought the auto-throttle wasn't working right.

The plane's tail hit a seawall just short of the runway, sending the Boeing 777 spinning before it broke apart and caught fire.

The pilots didn't understand exactly how the auto throttle worked, said the NTSB.

That complexity, it said, and training manuals that didn't clearly describe how the controls operated, contributed to the crash.

Three passengers were killed and over 180 injured.

The board made a raft of recommendations, including better training to explain auto-throttle functions.

Boeing says it's taking the recommendations under review.