Editing Flight recorder (section)

== Components ==

=== Flight data recorder ===
{{Redirect|Flight data recorder|the song by +/-|Xs on Your Eyes}}
[[File:Black box.aeroplane.JPG|thumb|A typical flight recorder]]
[[File:Grossi-7.png|thumb|Cockpit voice recorder and flight data recorder, each with an [[underwater locator beacon]] on the front]]
[[File:Underwaterlocatorbeacon.JPG|thumb|An [[underwater locator beacon]]; the [[ballpoint pen]] provides scale]]
[[File:Two-In-One Data Recorder.JPG|thumb|A cockpit voice and data recorder (CVDR), with its attached ULB visible on the left side of the unit]]
[[File:Flightrecorders.JPG|thumb|A flight data recorder and a cockpit voice recorder installed on their mounting trays in the rear fuselage of an aircraft]]
[[File:东航MU5735班机第二部黑匣子寻获现场 Second Black box of crashed flight MU5735 retrieved 1.jpg|thumb|The flight data recorder for crashed flight [[MU5735]].]]
A flight data recorder (FDR; also ADR, for ''accident data recorder'') is an electronic device employed to record instructions sent to any electronic systems on an aircraft.

The data recorded by the FDR are used for [[accidents and incidents in aviation|accident and incident]] investigation. Due to their importance in investigating accidents, these [[ICAO]]-regulated devices are carefully engineered and constructed to withstand the force of a high speed impact and the heat of an intense fire. Contrary to the popular term "black box", the exterior of the FDR is coated with heat-resistant [[safety orange|bright orange]] paint for high visibility in wreckage, and the unit is usually mounted in the aircraft's [[empennage|tail section]], where it is more likely to survive a crash. Following an accident, the recovery of the FDR is usually a high priority for the investigating body, as analysis of the recorded parameters can often detect and identify causes or contributing factors.<ref name="TSO-C124b-3B"/>

Modern day FDRs receive inputs via specific data frames from the [[flight-data acquisition unit]]s. They record significant [[flight]] parameters, including the control and [[actuator]] positions, engine information and [[Timestamp|time of day]]. There are 88 parameters required as a minimum under current US federal regulations (only 29 were required until 2002), but some systems monitor many more variables. Generally each parameter is recorded a few times per [[second]], though some units store "bursts" of data at a much higher [[frequency]] if the data begin to change quickly. Most FDRs record approximately 17–25 hours of data in a continuous loop.{{citation needed|date=March 2014}} It is required by regulations that an FDR verification check (readout) is performed annually in order to verify that all mandatory parameters are recorded.{{citation needed|date=May 2015}} Many aircraft today are equipped with an "event" button in the cockpit that could be activated by the crew if an abnormality occurs in flight. Pushing the button places a signal on the recording, marking the time of the event.<ref>{{cite web|url=http://www.industrial-electronics.com/aircraft_18b.html|title=Aircraft Electronics + Electrical Systems: Flight data and cockpit voice recorders|website=industrial-electronics.com|publisher=A Measurement-Testing network|access-date=March 27, 2019|archive-date=November 11, 2018|archive-url=https://web.archive.org/web/20181111062649/http://www.industrial-electronics.com/aircraft_18b.html|url-status=live}}</ref>

Modern FDRs are typically double wrapped in strong [[corrosion]]-resistant [[stainless steel]] or [[titanium]], with high-temperature [[Thermal insulation|insulation]] inside. Modern FDRs are accompanied by an [[underwater locator beacon]] that emits an ultrasonic "ping" to aid in detection when submerged. These beacons operate for up to 30 days and are able to operate while immersed to a depth of up to {{convert|6000|m|ft|sp=us}}.<ref name="OSA"/><ref name="SSFDR" />

=== 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"/>

=== Combined units ===
With the advent of digital recorders, the FDR and CVR can be manufactured in one fireproof, shock proof, and waterproof container as a combined digital cockpit voice and data recorder (CVDR). Currently, CVDRs are manufactured by [[L3Harris Technologies]]<ref name="L-3"/> and [[Hensoldt]]<ref>{{cite web |title=Flight and mission data recording & management - SferiRec |url=https://www.hensoldt.net/solutions/air/situational-awareness/flight-and-mission-data-recording-management-sferirec/ |publisher=Hensoldt |date=2019 |access-date=August 12, 2019 |archive-date=August 12, 2019 |archive-url=https://web.archive.org/web/20190812202525/https://www.hensoldt.net/solutions/air/situational-awareness/flight-and-mission-data-recording-management-sferirec/ |url-status=live }}</ref> among others.

Solid state recorders became commercially practical in 1990, having the advantage of not requiring scheduled maintenance and making the data easier to retrieve. This was extended to the two-hour voice recording in 1995.<ref>{{cite web|title=History of Flight Recorders|url=http://www.l-3ar.com/html/history.html|archive-url=https://web.archive.org/web/20131211231050/http://www.l-3ar.com/html/history.html |publisher=L3 Flight Recorders|archive-date=December 11, 2013 }}</ref>

=== Additional equipment ===
Since the 1970s, most large civil jet transports have been additionally equipped with a "[[quick access recorder]]" (QAR). This records data on a removable storage medium. Access to the FDR and CVR is necessarily difficult because they must be fitted where they are most likely to survive an accident; they also require specialized equipment to read the recording. The QAR recording medium is readily removable and is designed to be read by equipment attached to a standard desktop computer. In many airlines, the quick access recordings are scanned for "events", an event being a significant deviation from normal operational parameters. This allows operational problems to be detected and eliminated before an accident or incident results.

A '''flight-data acquisition unit''' (FDAU) is a unit that receives various discrete, analog and digital parameters from a number of sensors and [[avionic]] systems and then routes them to the FDR and, if installed, to the QAR. Information from the FDAU to the FDR is sent via specific data frames, which depend on the aircraft manufacturer.

Many modern aircraft systems are [[fly-by-wire|digital or digitally controlled]]. Very often, the digital system will include [[built-in test equipment]] which records information about the operation of the system. This information may also be accessed to assist with the investigation of an accident or incident.