Cockpit voice recording

Cockpit voice recorder

A Cockpit Voice Recorder (CVR) is a flight recorder used to record the audio environment in the flightdeck of an aircraft for the purpose of investigation of accidents and incidents. This is typically achieved by recording the signals of the microphones and earphones of the pilots headsets and of an area microphone in the roof of the cockpit. The current applicable FAA TSO is C123b titled Cockpit Voice Recorder Equipment.

Where an aircraft is required to carry a CVR and utilises digital communications the CVR is required to record such communications with air traffic control unless this is recorded elsewhere. As of 2005 it is an FAA requirement that the recording duration is a minimum of thirty minutes, but the NTSB have long recommended that it should be at least two hours.

Overview

A standard CVR is capable of recording 4 channels of audio data for a period of 2 hours. The original requirement was for a CVR to record for 30 minutes, but this has been found to be insufficient in many cases, significant parts of the audio data needed for a subsequent investigation having occurred more than 30 minutes before the end of the recording.

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. The original was the ARL Flight Memory Unit produced in 1957 by David Warren and an instrument maker named Tych Mirfield.

Other units used a single reel, with the tape spliced into a continuous loop, much as in an 8-track cartridge. The tape would circulate and old audio information would be overwritten every 30 minutes. Recovery of sound from magnetic tape often proves difficult if the recorder is recovered from water and its housing has been breached. Thus, the latest designs employ solid-state memory and use digital recording techniques, making them much more resistant to shock, vibration and moisture. With the reduced power requirements of solid-state recorders, it is now practical to incorporate a battery in the units, so that recording can continue until flight termination, even if the aircraft electrical system fails.

Like the flight data recorder (FDR), the CVR is typically mounted in the empennage of an airplane to maximize the likelihood of its survival in a crash.

Future devices

The U.S. National Transportation Safety Board has asked for the installation of cockpit image recorders in large transport aircraft to provide information that would supplement existing CVR and FDR data in accident investigations. They also recommended image recorders be placed into smaller aircraft that are not required to have a CVR or FDR.

Such systems, estimated to cost less than $8,000 installed, typically consist of a camera and microphone located in the cockpit to continuously record cockpit instrumentation, the outside viewing area, engine sounds, radio communications, and ambient cockpit sounds. As with conventional CVRs and FDRs, data from such a system is stored in a crash-protected unit to ensure survivability.

Since the recorders can sometimes be crushed into unreadable pieces, or even never located in deep water, some modern units are self-ejecting (taking advantage of kinetic energy at impact to separate themselves from the aircraft) and also equipped with radio and sonar beacons (see emergency locator transmitter) to aid in their location.

On 19 July 2005, the Safe Aviation and Flight Enhancement Act of 2005 was introduced and referred to the Committee on Transportation and Infrastructure of the U.S. House of Representatives. This bill would require installation of a second cockpit voice recorder, digital flight data recorder system and emergency locator transmitter that utilizes combination deployable recorder technology in each commercial passenger aircraft that is currently required to carry each of those recorders. The deployable recorder system would be ejected from the rear of the aircraft at the moment of an accident. The bill was referred to the Subcommittee on Aviation and has not progressed since.

Related

The U.S. National Transportation Safety Board has recommended that railroad voice recorders be required in locomotives.

Cultural references

The Neue Deutsche Härte band Rammstein's album Reise, Reise is made to look like a CVR; it also includes a recording from a crash. The recording is from the last 1-2 minutes of the CVR of Japan Airlines Flight 123, which crashed on August 12, 1985, killing 520 people; JAL123 is the deadliest single-aircraft disaster in history.

Members of Collective: Unconscious made a theatrical presentation based on transcripts from CVR recordings.

A play called Charlie Victor Romeo has a script consisting of almost verbatim cockpit voice recordings.

Survivor, a novel by Chuck Palahniuk, is about a cult member who dictates his life story to a flight recorder before the plane runs out of gas and crashes.

See also

References

External links

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