 Warren's invention, which relied on magnetic recording media, allowed easy erasing and re-recording, which made it practical for routine line service.Warren's concept of cockpit voice recording added a new dimension to instrument data in flight recorders, and has proved extremely valuable for accident investigation.Some accidents where the CVR played a prominent role were solved not by the crew's recorded voices, but by other sounds incidentally recorded on the CVR, which provided a vital clue to the accident cause.