Cockpit Voice Recorder (CVR): Recording Scope, Activation, and Survivability
The CVR is designed to record the audio environment of the flight deck to assist in accident investigations.
Operation and Capability
- Recording Duration: Historically preserves the last 2 hours of recording (loop recording). Newer regulations often mandate longer durations (e.g., 25 hours) for modern aircraft.
- Activation: Automatically energized:
- In flight.
- On the ground with at least one engine running.
- Components:
- Area Microphone: Typically located in the overhead panel to capture general cockpit sounds (switches, alerts, conversations).
- Crashproof Recorder: Housed in the aft section (tail) for maximum survivability, fitted with an Underwater Locating Beacon (ULB).
- Control Panel: Includes a test button and an Event Button to mark specific moments on the tape for rapid retrieval.
Recorded Information
According to CS-25 / EASA AIR OPS, the CVR must record:
- Radio Communications: Transmitted and received.
- Aural Environment: Via the Area Microphone (cockpit sounds).
- Interphone: Communications between flight crew members.
- Navigation Aids: Audio idents (Morse code) from nav radios.
- Public Address (PA): Announcements made by the flight crew.
- Note: It does not typically record communications between flight attendants (inter-cabin stations) unless they call the cockpit.