Cockpit Voice Recorder (CVR)
The Cockpit Voice Recorder (CVR) would be better named the cockpit audio recorder as it provides a record of the total audio environment in the cockpit area.
This includes crew conversation, radio transmissions, aural alarms, control movements, switch activations, engine noise and airflow noise.
Traditionally the CVR retains the last 30 minutes of audio on tape operating on the endless-loop principle. However modern CVR's use memory chips rather than magnetic tape as the recording medium and can store the last 2 hours of audio information.
Approximately 80% of aircraft accidents involve human factors which, in most cases, means crew performance was a factor. Consequently the CVR often tells accident investigators why an accident occurred.