SOME ten years ago, the regulatory authorities in the United States prepared legislation enforcing the carriage of flight data recorders on commercial passenger‐carrying aircraft above 12,500 lb. all‐up weight. Since that time other countries have introduced similar regulations. The intention of the original requirements was to record parameters describing the aircraft flight path; as an example the current U.S. regulations call for four parameters to be recorded with with respect to time i.e. airspeed, altitude, vertical acceleration and heading. The present British regulations also require pitch, and the French specify marker beacon flyover.