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An example of an FDR (flight data recorder). (English translation: FLIGHT RECORDER DO NOT OPEN)
Flight data recorder and cockpit voice recorder

A flight data recorder (FDR) (also ADR, for accident data recorder) is a kind of flight recorder. It is a device used to record specific aircraft performance parameters. Another kind of flight recorder is the cockpit voice recorder (CVR), which records conversation in the cockpit, radio communications between the cockpit crew and others (including conversation with air traffic control personnel), as well as ambient sounds. In some cases, both functions have been combined into a single unit.

Popularly referred to as a "black box," the data recorded by the FDR is used for accident investigation, as well as for analyzing air safety issues, material degradation and engine performance. Due to their importance in investigating accidents, these ICAO-regulated devices are carefully engineered and stoutly constructed to withstand the force of a high speed impact and the heat of an intense fire. Contrary to the "black box" reference, the exterior of the FDR is coated with heat-resistant 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 severe crash. Following an accident, recovery of the "black boxes" is second in importance only to the rescue of survivors and recovery of human remains.



As with many successful devices, probably no single person could be credited with the invention of the flight data recorder. However, 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. This was an essentially photograph-based device, because the record was made on a scrolling eight meters long by 88 milimeters wide photographic film. The latent image was made by a thin ray of light deviated by a mirror tilted according to the magnitude of the data to record (altitude, speed, etc)[1][2]. A pre-production run of 25 "HB" recorders was ordered in 1941 and HB recorders remained in use in French test centers well into the seventies[3]. In 1947, Hussenot, Beaudouin and associate Marcel Ramolfo founded the Société Française d'Instruments de Mesure to market their design. This company went on becoming a major supplier of data recorders, used not only aboard aircraft but also trains and other vehicles. SFIM is today part of the Safran group and is still present on the flight recorder market.

The advantage of the film technology was that it could be easily developed afterwards and provide a durable, visual feedback of the flight parameters without needing any playback device. On the other hand, unlike magnetic bands or later flash memory-based technology, a photographic film cannot be erased and recycled, and so it must be changed periodically. As such, this technology was reserved for one-shot uses, mostly during planned test flights; and it was not mounted aboard civilian aircraft during routine commercial flights. Also, the cockpit conversation was not recorded.

The first prototype coupled FDR/CVR designed with civilian aircraft in mind, for explicit post-crash examination purposes, was produced in 1956 by Dr. David Warren of the then Aeronautical Research Laboratories of Melbourne, Australia[4]. In 1953 and 1954, a series of fatal accidents involving the De Havilland DH106 Comet prompted the grounding of the entire fleet pending an investigation. Dr. Warren, a chemist specializing in aircraft fuels, was involved in a professional committee discussing the possible causes. Since there had been neither witnesses nor survivors, Dr. Warren conceived of a crash-survivable method to record the flight crew's conversation (and other pre-crash data), reasoning they would greatly assist in determining a cause and enabling the prevention of future, avoidable accidents of the same type.

Despite his 1954 report entitled "A Device for Assisting Investigation into Aircraft Accidents" and a 1957 prototype FDR called "The ARL Flight Memory Unit", aviation authorities from around the world were largely uninterested. This changed in 1958 when Sir Robert Hardingham, the Secretary of the UK Air Registration Board, visited the ARL and was introduced to Warren.

1962 ARL encoder/recorder units by Lane Sear and Wally Boswell.

The Aeronautical Research Laboratory allocated Dr. Warren an engineering team to develop the prototype to airborne stage. The team, consisting of electronics engineers Lane Sear, Wally Boswell and Ken Fraser developed a working design incorporating a fire and shockproof case, a reliable system for encoding and recording aircraft instrument readings and voice on one wire, and a ground-based decoding device. The ARL system became the "Red Egg", made by the British firm of S. Davall & Son. The "Red Egg" got its name from its shape and bright red color. In 1960, after the crash of an aircraft at Mackay (Queensland), the inquiry judge strongly recommended that flight recorders be installed in all airliners. Australia then became the first country in the world to make cockpit-voice recording compulsory [5][6].

The origin of the term "Black Box" is uncertain. One explanation comes from the early film-based design of flight data recorders, which required the inside of the recorder to be perfectly dark to prevent light leaks from corrupting the record, as in a photographer's darkroom[7]. Another explanation of the "black box" name came from a meeting about Warren's "Red Egg", when afterwards a journalist told Dr. Warren, "This is a wonderful black box." The unit itself was based on an EMI Minifon wire recorder (originally a 1950's espionage gadget from the west-German manufacterer Protona Monske) fitted into a perspex box firmly screwed together.


The design of today's FDR is governed by the internationally recognised 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[8] documents EUROCAE ED55, ED56A and ED112 (Minimum Operational Performance Specification for Crash Protected Airborne Recorder Systems). In the United States, the Federal Aviation Administration (FAA) regulates all aspects of U.S. aviation, and cites design requirements in their Technical Standard Order,[9] based on the EUROCAE documents (as do the aviation authorities of many other countries).

After the crash of Gol Transportes Aéreos Flight 1907, Brazilian Air Force personnel recover the flight data recorder of PR-GTD, the Boeing 737-8EH used for the flight, in the Amazon Rainforest in Mato Grosso, Brazil.

Currently, EUROCAE specifies that a recorder must be able to withstand an acceleration of 3400 g (33 km/s²) for 6.5 milliseconds. This is roughly equivalent to an impact velocity of 270 knots and a deceleration or crushing distance of 450 cm. Additionally, there are requirements for penetration resistance, static crush, high and low temperature fires, deep sea pressure, sea water immersion, and fluid immersion.

Modern day FDRs receive inputs via specific data frames from the FDAU units. They record significant flight parameters, including the control and actuator positions, engine information and time of day. There are 88 parameters required as a minimum under current U.S. 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 begins to change quickly. Most FDRs record approximately 17–25 hours worth of data in a continuous loop. It is required by regulations, that an FDR verification check (readout) is performed annually, in order to verify that all mandatory parameters are recorded.

This has also given rise to flight data monitoring programs, whereby flights are analyzed for optimum fuel consumption and dangerous flight crew habits. The data from the FDR is transferred, in situ, to a solid state recording device and then periodically analyzed with some of the same technology used for accident investigations.

FDRs are usually located in the rear of the aircraft, typically in the tail. In this position, the entire front of the aircraft is expected to act as a "crush zone" to reduce the shock that reaches the recorder. Also, modern FDRs are typically double wrapped, in strong corrosion-resistant stainless steel or titanium, with high-temperature insulation inside. They are usually bright orange. They are designed to emit a locator beacon for up to 30 days, and can operate immersed to a depth of up to 6,000 meters (20,000 ft).[10][11]

Future devices

Since the recorders can sometimes be crushed into unreadable pieces, or even 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.

Alternatively, other aircraft such as the Space Shuttle Orbiter do not possess an FDR but instead use down-links to transfer such data. This kind of system could potentially see wider use in aviation in modified form.

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, 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.[12][13] One problem for the military is that these commercial devices offer no protection of the data that has been recorded. Therefore, they have the potential for exposing military secrets if the device is captured by non-friendly forces and exploited

See also


  1. ^ Jean-Claude Fayer, Vols d’essais: Le Centre d’Essais en Vol de 1945 à 1960, published by E.T.A.I. (Paris), 2001, 384 pages, ISBN 2-7268-8534-9
  2. ^ See page 207 of Denis Beaudouin, Chloé Beaudouin, Charles Beaudouin: une histoire d'instruments scientifiques, published by EDP Sciences Editions, 2005, 285 pages, ISBN 2868838073, available on Google Books
  3. ^ See page 206 and 209 of Beaudouin & Beaudouin, op. cit.
  4. ^ Australian Research Laboratories
  5. ^, Dave Warren - Inventor of the black box flight recorder, [1]
  6. ^ Neil Campbell, The Evolution of Flight Data Analysis, Proc. Australian Society of Air Safety Investigators conference, 2007, visible here.
  7. ^ See page 210 of Beaudouin & Beaudouin, op. cit.
  8. ^ European Organisation for Civil Aviation Equipment
  9. ^ TSO-C124a FAA Regs.
  10. ^ "Flight Data Recorder OSA".  
  11. ^ "SSFDR Solid State Flight Data Recorder, ARINC 747 - TSO C 124 - ED 55".  
  12. ^ Search Results - THOMAS (Library of Congress)
  13. ^ Search Results - THOMAS (Library of Congress)

External links


General information

Dr David Warren

PD-icon.svg This article incorporates public domain material from websites or documents of the National Transportation Safety Board.


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