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Cockpit Voice Recorder (CVR)
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Cockpit Voice Recorder (CVR) - a device used to record the audio environment in the flight deck for accidents and incident investigation purposes. The CVR records and stores the audio signals of the microphones and earphones of the pilots’ headsets and of an area microphone installed in the cockpit.
According to the provisions in ICAO Annex 6 “Operation of Aircraft”, Vol I:
- Fixed-wing aeroplane and helicopters shall be equipped with a cockpit voice recorder with a recording duration of at least 30 minutes of its operation;
- Fixed-wing aeroplanes with a maximum take-off mass of more than 5 700 kg and for which the certificate of airworthiness is first issued after 1 January 2003 shall be equipped with a CVR with a recording duration of two hours; and
- Helicopters for which the certificate of airworthiness is first issued after 1 January 2003 shall be equipped with a CVR with a recording duration of two hours.
International Civil Aviation Organisation (ICAO) recommends the following to Contracting States:
- A CVR, installed in aeroplanes of a maximum certificated take-off mass of over 5 700 kg for which the individual certificate of airworthiness is first issued on or after 1 January 1990, should be capable of retaining the information recorded during at least the last two hours of its operation
- A CVR, installed in helicopters for which the individual certificate of airworthiness is first issued on or after 1 January 1990, should be capable of retaining the information recorded during at least the last two hours of its operation.
Additional ICAO provisions, in force from 1 January 2007, require that all aeroplanes which utilise data link communications and are required to carry a CVR shall record, on a flight recorder, all data link communications to and from the aeroplane. The minimum recording duration shall be equal to the duration of the CVR, and shall be correlated to the recorded cockpit audio. Also, sufficient information to derive the content of the data link communications message and, whenever practical, the time the message was displayed to or generated by the crew shall be recorded.
CVR performance requirements are contained in the Minimum Operational Performance Specification (MOPS) document for Flight Recorder Systems of the European Organization for Civil Aviation Equipment (European Organisation for Civil Aviation Equipment (EUROCAE)).
The earliest CVRs used analog wire recording, later replaced by analog magnetic tape. Some of the tape units used two reels, with the tape automatically reversing at each end. Currently, the most widely used CVRs in commercial transportation are capable of recording 4 channels of audio data for a period of 2 hours. The previous requirement for a CVR to record for 30 minutes was found to be insufficient in many cases. In some accident investigations, significant parts of the pertinent audio data were missing as they occurred more than 30 minutes before the end of the recording (the tape capacity would result in audio information being overwritten every 30 min.)
The latest CVR use solid-state memory and digital recording techniques which make them much more resistant to shock, vibration and moisture. With the reduced power requirements of solid-state recorders, it is possible to incorporate a battery in the units, so that recording can continue until flight termination, even if the aircraft electrical system fails.
Regarding the introduction of video recordings in the cockpit: the attempts of some operators to introduce on-board video recording in the flight deck have met very little success to date due to resistance from pilot professional organisations and unions.
- ICAO Annex 6, Operation of Aircraft, Vol I, Attachment D and Vol III)
- Cockpit Voice Recorder Handbook for Aviation Accident Investigations, NTSB, December 2019