Editing Flight recorder (section)

=== Cockpit voice recorder ===
[[File:Flightrecorder.jpg|thumb|Both side views of a cockpit voice recorder, one type of flight recorder]]
A cockpit voice recorder (CVR) is a flight recorder used to record the audio environment in the [[cockpit|flight deck]] 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]] [[Technical Standard Order|TSO]] is C123b titled Cockpit Voice Recorder Equipment.<ref name="TSO-C123b"/>

Where an aircraft is required to carry a CVR and uses digital communications the CVR is required to record such communications with air traffic control unless this is recorded elsewhere. {{As of|2008}} it is an FAA requirement that the recording duration is a minimum of two hours.<ref name="359-FAR"/> The [[European Aviation Safety Agency]] increased the recording duration to 25 hours in 2021.<ref>{{Cite web |last=Bellamy III |first=Woodrow |date=2019-04-13 |title=L3 Has New Data, Voice Recorders for EASA's 2021 Mandate |url=https://www.aviationtoday.com/2019/04/13/l3-new-cockpit-recorders-easas-2021-mandate/ |access-date=2023-06-19 |website=Avionics International |language=en}}</ref> In 2023, the FAA proposed extending requirements to 25 hours to help in investigations like runway incursions.<ref>{{Cite web |last=Walsh |first=Amelia |date=2023-03-21 |title=FAA Proposes Extending Cockpit Voice Recording to 25 Hours |url=https://www.flyingmag.com/faa-proposes-extending-cockpit-voice-recording-to-25-hours/ |access-date=2023-06-19 |website=FLYING Magazine |language=en-US}}</ref><ref>{{Cite web |last=Wallace |first=Greg |date=2023-03-17 |title=The FAA proposes lengthening cockpit voice recording time to 25 hours - CBS Sacramento |url=https://www.cbsnews.com/sacramento/news/the-faa-proposes-lengthening-cockpit-voice-recording-time-to-25-hours/ |access-date=2023-06-19 |website=CBS News |language=en-US}}</ref> In a January 2024 press conference on [[Alaska Airlines Flight 1282]], [[National Transportation Safety Board]] (NTSB) chair [[Jennifer Homendy]] again called for extending retention to 25 hours, rather than the currently-mandated 2 hours, on all existing devices, rather than only newly manufactured ones.<ref>{{Cite web |last=Villamizar |first=Helwing |date=2024-01-08 |title=No Data on Flight 1282 Cockpit Voice Recorder, NTSB Calls out FAA |url=https://airwaysmag.com/no-data-1282-cockpit-recorder-ntsb/ |access-date=2024-01-08 |website=Airways |language=en-US}}</ref>

A standard CVR is capable of recording four channels of audio data for a period of two hours. The original requirement was for a CVR to record for 30 minutes, but this has been found to be insufficient in many cases because significant parts of the audio data needed for a subsequent investigation occurred more than 30 minutes before the end of the recording.<ref name=BlackBox30min.NYPost1999>{{cite news
   |newspaper=[[The New York Post]]
   |title=Learjet probe focuses on value replaced 2 days before crash
   |quote=The record works on a half hour loop, so it has no information about the crucial first hour
   |author=Tracy Connor |date=October 28, 1999 |page=18}}</ref>

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 [[Australians|Australian]] [[David Warren (inventor)|David Warren]] and instrument maker [[Theon Numa (Tych) Mirfield|Tych Mirfield]].<ref>{{Cite web|title=ARL Flight Memory Recorder|url=https://collections.museumsvictoria.com.au/articles/3720|access-date=October 5, 2021|website=Museums Victoria Collections|archive-date=October 5, 2021|archive-url=https://web.archive.org/web/20211005184905/https://collections.museumsvictoria.com.au/articles/3720|url-status=live}}</ref><ref>{{Cite journal|last=Mirfield|first=Theon Neuma|date=May 1964|title=Miniature wire recording desks with limited memory|url=http://merfield.com/genealogy/theon-mirfield-1964-miniature-wire-recording-decks-with-limited-memory.zip|journal=The Australian Journal of Instrument Technology|volume=May|pages=94–100|access-date=October 20, 2019|archive-date=October 20, 2019|archive-url=https://web.archive.org/web/20191020065137/http://merfield.com/genealogy/theon-mirfield-1964-miniature-wire-recording-decks-with-limited-memory.zip|url-status=live}}</ref>

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 drive|solid-state memory]] and use fault tolerant [[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 FDR, the CVR is typically mounted in the rear of the airplane [[fuselage]] to maximize the likelihood of its survival in a crash.<ref name="1457-FAR"/>