The National Transportation Safety Board found Boeing and the FAA responsible for "multiple system failures," leading to Alaska Airlines' door blowing off mid-flight last year near Portland, Oregon.

One of a team of 24 had opened a door-plug before, but he was on vacation — leading the NTSB to criticise Boeing's on-the-job training.

The National Transportation Safety Board recommended more hands-on training and oversight at Boeing after an Alaska Airlines jet came apart in flight.