0 a small machine that records information about an aircraft during its flight, used to discover the cause of an accident:
2 a system or process that uses information to produce a particular set of results, but that works in a way that is secret or difficult to understand:
3 a piece of electronic equipment used to record and store information:
4 a piece of equipment on an aircraft that records the plane's movements and positions during a flight, and which can give important information if the plane has an accident:
The second, often described as the "black box", provided conclusive information concerning course, altitude, and other data relating to the flight and functioning of the aircraft at the relevant period of time.