American Airlines passengers unaware of cockpit crisis
When the captain of an American Airlines flight from Phoenix to Boston died at the controls, his 147 passengers were unaware of the extent of the crisis on board.
The first officer took over the controls of flight 550 and diverted the jet to Syracuse, New York.
A golden rule of commercial flying is not to panic the passengers, pilots say - as BBC News explains.
Video produced by James Reevell