Black box in aviation

In aviation, a "black box" (they are actually bright orange, to facilitate their being found after a crash) is an audio or data recording device in an airplane or helicopter.

 The cockpit voice recorder records the conversation of the pilots and the flight data recorder logs information about controls and sensors, so that in the event of an accident investigators can use the recordings to assist in the investigation. 

The two aviation recorders currently combined in a single assembly referred to by the media as a "black box" are the Flight Data Recorder and a Cockpit Sound Recorder also identified as a Cockpit Voice Recorder.