Flight recorder

thumb|A modern flight data recorder; the [[underwater locator beacon is the small cylinder on the far right. (Translation of warning message in French: "Flight recorder do not open".) The warning appears in English on the other side.]]

thumb|Cold War-era [[Soviet Union|Soviet MS-61 cockpit voice recorder from a MiG-21 interceptor]]

A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of aviation accidents and incidents. The device may be referred to colloquially as a "black box", an outdated name which has become a misnomer because they are required to be painted bright orange, to aid in their recovery after accidents.

thumb|Flight data recorder recovered from the [[Potomac River on 2 February 2025, from one of the aircraft involved in the 2025 Potomac River mid-air collision. ]]

There are two types of flight recording devices: the flight data recorder (FDR) preserves the recent history of the flight by recording dozens of parameters collected several times per second; the cockpit voice recorder (CVR) preserves the recent history of the sounds in the cockpit, including the conversation of the pilots. The two devices may be combined into a single unit. Together, the FDR and CVR document the aircraft's flight history, which may assist in any later investigation.

The two flight recorders are required by the International Civil Aviation Organization to be capable of surviving conditions likely to be encountered in a severe aircraft accident. They are specified to withstand an impact of 3400 g and temperatures of over by EUROCAE ED-112. They have been a mandatory requirement in commercial aircraft in the United States since 1967. After the unexplained disappearance of Malaysia Airlines Flight 370 in 2014, commentators have called for live streaming of data to the ground, as well as extending the battery life of the underwater locator beacons.

History

thumb|A Fairchild A100 cockpit voice recorder, on display in the [[Deutsches Museum. This is a magnetic-tape unit built to an old standard, TSO C84, as shown on the nameplate. The text on the side in French says "Flight recorder do not open".]]

Early designs

One of the earliest and proven attempts was made by François Hussenot and Paul Beaudouin in 1939 at the Marignane flight test center, France, with their "type HB" flight recorder; they were essentially photograph-based flight recorders, because the record was made on a scrolling photographic film long by wide. The latent image was made by a thin ray of light deviated by a mirror tilted according to the magnitude of the data to be recorded (altitude, speed, etc.).

During World War II, both British and American air forces successfully experimented with aircraft voice recorders. In August 1943, the USAAF conducted an experiment with a magnetic wire recorder to capture the inter-phone conversations of a B-17 bomber flight crew on a combat mission over Nazi-occupied France. The recording was broadcast back to the United States by radio two days afterwards.

Australian designs

thumb|Video clip of 1985 [[ABC News (Australia)|ABC News report interviewing David Warren about his invention]]

In 1953, while working at the Aeronautical Research Laboratories (ARL) of the Defence Science and Technology Organisation in Port Melbourne,

Warren built a prototype FDR called "The ARL Flight Memory Unit" in 1956, It was designed with civilian aircraft in mind, explicitly for post-crash examination purposes.

Carriage of data recording equipment became mandatory in UK-registered aircraft in two phases; the first, for new turbine-engined public transport category aircraft over in weight, was mandated in 1965, with a further requirement in 1966 for piston-engined transports over , with the earlier requirement further extended to all jet transports. One of the first UK uses of the data recovered from an aircraft accident was that recovered from the Royston "Midas" data recorder that was on board the British Midland Argonaut involved in the Stockport Air Disaster in 1967.

American designs

thumb|NTSB investigators recover flight data recorder and cockpit voice recorder from [[UPS Airlines Flight 1354]]

thumb|NTSB staff examine the memory boards of the cockpit voice recorder from [[Atlas Air Flight 3591. The boards may have suffered water damage.]]

A flight recorder was invented and patented in the United States by James J. Ryan. Ryan's "Flight Recorder" patent was filed in August 1953 and approved on November 8, 1960, as US Patent 2,959,459. A second patent by Ryan for a "Coding Apparatus For Flight Recorders" is US Patent 3,075,192 dated January 22, 1963.

A "Cockpit Sound Recorder" (CSR) was independently invented and patented by Edmund A. Boniface Jr., an aeronautical engineer at Lockheed Aircraft Corporation. He originally filed with the US Patent Office on February 2, 1961, as an "Aircraft Cockpit Sound Recorder". The 1961 invention was viewed by some as an "invasion of privacy". Subsequently, Boniface filed again on February 4, 1963, for a "Cockpit Sound Recorder" (US Patent 3,327,067) with the addition of a spring-loaded switch which allowed the pilot to erase the audio/sound tape recording at the conclusion of a safe flight and landing.

Boniface's participation in aircraft crash investigations in the 1940s and in the accident investigations of the loss of one of the wings at cruise altitude on each of two Lockheed Electra turboprop powered aircraft (Flight 542 operated by Braniff Airlines in 1959 and Flight 710 operated by Northwest Orient Airlines in 1961) led to his wondering what the pilots may have said just prior to the wing loss and during the descent as well as the type and nature of any sounds or explosions that may have preceded or occurred during the wing loss.

His patent was for a device for recording audio of pilot remarks and engine or other sounds to be "contained with the in-flight recorder within a sealed container that is shock mounted, fireproofed and made watertight" and "sealed in such a manner as to be capable of withstanding extreme temperatures during a crash fire". The CSR was an analog device which provided a continuous erasing/recording loop (lasting 30 or more minutes) of all sounds (explosion, voice, and the noise of any aircraft structural components undergoing serious fracture and breakage) which could be overheard in the cockpit.

Terminology

thumb|[[Gee (navigation)|GEE airborne equipment, with the R1355 receiver on the left and the Indicator Unit Type 62A "black box" on the right.]]

The term "black box" was a World War II British phrase, originating with the development of radio, radar, and electronic navigational aids in British and Allied combat aircraft. These often-secret electronic devices were encased in non-reflective black boxes or housings.  The earliest identified reference to "black boxes" occurs in a May 1945 Flight article, "Radar for Airlines", describing the application of wartime RAF radar and navigational aids to civilian aircraft: "The stowage of the 'black boxes' and, even more important, the detrimental effect on performance of external aerials, still remain as a radio and radar problem." (The term "black box" is used with a different meaning in science and engineering, describing a system exclusively by its inputs and outputs, with no information whatsoever about its inner workings.)

Magnetic tape and wire voice recorders had been tested on RAF and USAAF bombers by 1943 thus adding to the assemblage of fielded and experimental electronic devices employed on Allied aircraft. As early as 1944 aviation writers envisioned use of these recording devices on commercial aircraft to aid incident investigations. When modern flight recorders were proposed to the British Aeronautical Research Council in 1958, the term "black box" was in colloquial use by experts.

By 1967, when flight recorders were mandated by leading aviation countries, the expression had found its way into general use: "These so-called 'black boxes' are, in fact, of fluorescent flame-orange in colour." The formal names of the devices are flight data recorder and cockpit voice recorder. The recorders must be housed in boxes that are bright orange in color to make them more visually conspicuous in the debris after an accident.

Modern FDRs are typically double wrapped in strong corrosion-resistant stainless steel or titanium, with high-temperature 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 . In 2023, the FAA proposed extending requirements to 25 hours to help in investigations like runway incursions. 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.

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.

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 Australian David Warren and instrument maker 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 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. among others. The Enhanced Airborne Flight Recorder (EAFR), manufactured by General Electric and fitted to the Boeing 787 Dreamliner, is a combined recorder which also includes a Recorder Independent Power Supply (RIPS) to allow continued operation in the event of a power failure.

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.

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 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.

Specifications

thumb|Cockpit voice recorder memory module of PR-GTD, a [[Gol Transportes Aéreos Flight 1907|Gol Transportes Aéreos Boeing 737-8EH SFP, found in the Amazon in Mato Grosso, Brazil.]]

thumb|After the crash of [[Gol Transportes Aéreos Flight 1907, Brazilian Air Force personnel show the recovered flight data recorder]]

The design of today's FDR is governed by the internationally recognized standards and recommended practices relating to flight recorders which are contained in ICAO Annex 6 which makes reference to industry crashworthiness and fire protection specifications such as those to be found in the European Organisation for Civil Aviation Equipment Additionally, there are requirements for penetration resistance, static crush, high and low temperature fires, deep sea pressure, sea water immersion, and fluid immersion.

EUROCAE ED-112 (Minimum Operational Performance Specification for Crash Protected Airborne Recorder Systems) defines the minimum specification to be met for all aircraft requiring flight recorders for recording of flight data, cockpit audio, images and CNS / ATM digital messages and used for investigations of accidents or incidents. The compliance deadline for that regulation was extended several times, until June 1944 when the requirement was rescinded due to maintenance problems and the lack of parts due to World War 2.

The ARINC Standards are prepared by the Airlines Electronic Engineering Committee (AEEC). The 700 Series of standards describe the form, fit, and function of avionics equipment installed predominately on transport category aircraft. The FDR is defined by ARINC Characteristic 747. The CVR is defined by ARINC Characteristic 757.

Post-incident overwriting of voice data by Nigerian crews led to a 2023 All Operators Letter reinforcing that this practice is forbidden.

Proposed requirements

Deployable recorders

The NTSB recommended in 1999 that operators be required to install two sets of CVDR systems, with the second CVDR designed to be ejected from the aircraft prior to impact with the ground or water. Ejection would be initiated by computer based on sensor information indicating an crash is imminent. A deployable recorder combines the cockpit voice/flight data recorders and an emergency locator transmitter (ELT) in a single unit. The unit would be designed to eject and float away from the aircraft and survive its descent to the ground, or float on water indefinitely. It would be equipped with satellite technology to aid in prompt recovery. Deployable CVDR technology has been used by the US Navy since 1993. was introduced on June 26, 2003, by Congressman David Price (D-NC) and Congressman John Duncan (R-Tenn.) in a bipartisan effort to ensure investigators have access to information immediately following accidents to transport category aircraft.

On January 8, 2015, before the recovery of the flight recorders, an anonymous ICAO representative said: "The time has come that deployable recorders are going to get a serious look." A second ICAO official said that public attention had "galvanized momentum in favour of ejectable recorders on commercial aircraft". In the Alaska Airlines Flight 1282 accident, the Cockpit Voice Recorder functioned properly but the data was overwritten as the CVR remained powered, and functioning. The critical accident data was overwritten by over two hours of post-incident sounds until a maintenance crew could enter the aircraft after the incident and power down the CVR.

Image recorders

The NTSB 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 have recommended that image recorders be placed into smaller aircraft that are not required to have a CVR or FDR.

Cultural references

The artwork for the 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 Air Lines Flight 123, which crashed on August 12, 1985, killing 520 people; JAL123 is the deadliest single-aircraft disaster in history.
Members of the performing arts collective Collective:Unconscious made a theatrical presentation of a play called Charlie Victor Romeo with a script based on transcripts from CVR voice recordings of nine aircraft emergencies. The play features the famous United Airlines Flight 232 that crash-landed in a cornfield near Sioux City, Iowa, after suffering a catastrophic failure of one engine and most flight controls.
In stand-up comedy, many jokes have been made asking why the entire airplane is not made out of the material used to make black boxes, given that the black box survives the crash (it's because then it would be too heavy to fly). This is referenced in the 2001 Chris Rock movie Down to Earth, although the original joke is widely credited to George Carlin.

References

External links

Cockpit Voice Recorder Database
'The ARL 'Black Box' Flight Recorder': Melbourne University history honors thesis on the development of the first cockpit voice recorder by David Warren
Finnish Mata-Hari Flight Recorder in Museums of Tampere City
"Beyond the Black Box: Instead of storing flight data on board, aircraft could easily send the information in real time to the ground", by Krishna M. Kavi, IEEE Spectrum, August 2010
David Warren interview transcript 2002, ABC TV (Australia)
David Warren interview transcript 2003, ABC TV (Australia)
etep, Flight Recorder designer
Heavy Vehicle EDR information site for black box technology
IRIG 106 Chapter 10: Flight data recorder digital recorder standard
Public domain photos of recorders
Popular Mechanics, March 19, 2008
"His Crashes Helped Make Ours Less Dangerous"
First modern flight recorder "Mata Hari" at display in Tampere Vapriikki Museum Centre.