My father was an aviator, flight engineer.
“Flight Data Recorder (FDR) is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters. Popularly referred to as a "black box" by the media, the data recorded by the FDR is used for accident investigation, as well as for analyzing air safety issues, material degradation and engine performance.”
International Civil Aviation Organization (ICAO), Annex 6