Flight recorder
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 The device may be referred to colloquially as a "black box", an outdated name which has become a misnomer because they are required to be painted bright orange, to aid in their recovery after accidents.
File:Flight data recorder recovered from the Potomac River on 2 February 2025.jpg|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 preserves the recent history of the flight by recording dozens of parameters collected several times per second; the cockpit voice recorder 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
In seafaring, a device which recorded the position of different vessels in case of an accident was patented by John Sen Inches Thomson in January, 1897.File:2002-dmuseum-luftfahrt-014-650.jpg|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. A pre-production run of 25 "HB" recorders was ordered in 1941, and HB recorders remained in use in French flight test centers well into the 1970s.In 1947, Hussenot founded the Société Française des Instruments de Mesure with Beaudouin and another associate, so as to market his invention, which was also known as the "hussenograph". This company went on to become 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 in the flight recorder market. The advantage of the film technology was that it could be easily developed afterwards and provides a durable, visual feedback of the flight parameters without needing any playback device. On the other hand, unlike magnetic tapes or later flash memory-based technology, a photographic film cannot be erased and reused, and so must be changed periodically. The technology was reserved for one-shot uses, mostly during planned test flights: it was not mounted aboard civilian aircraft during routine commercial flights. Also, cockpit conversation was not recorded.
Another form of flight data recorder was developed in the UK during World War II. Len Harrison and Vic Husband developed a unit that could withstand a crash and fire to keep the flight data intact. The unit was the forerunner of today's recorders, in being able to withstand conditions that aircrew could not. It used copper foil as the recording medium, with various styli, corresponding to various instruments or aircraft controls, indenting the foil. The foil was periodically advanced at set time intervals, giving a history of the aircraft's instrument readings and control settings. The unit was developed at Farnborough for the Ministry of Aircraft Production. At the war's end, the Ministry got Harrison and Husband to sign over their invention to it and the Ministry patented it under British patent 19330/45.
The first modern flight data recorder, called "Mata-Hari", named after the famous spy, was created in 1942 by Finnish aviation engineer Veijo Hietala. This black high-tech mechanical box was able to record all required data during test flights of fighter aircraft that the Finnish Air Force repaired or built in its main aviation factory in Tampere, Finland.
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
In 1953, while working at the Aeronautical Research Laboratories of the Defence Science and Technology Organisation in Port Melbourne, Australian research scientist David Warren conceived a device that would record not only the instrument readings, but also the voices in the cockpit. In 1954 he published a report entitled "A Device for Assisting Investigation into Aircraft Accidents".Warren built a prototype FDR called "The ARL Flight Memory Unit" in 1956, and in 1958 he built the first combined FDR/CVR prototype. It was designed with civilian aircraft in mind, explicitly for post-crash examination purposes. Aviation authorities from around the world were largely uninterested at first, but this changed in 1958 when Sir Robert Hardingham, the secretary of the British Air Registration Board, visited the ARL and was introduced to David Warren. Hardingham realized the significance of the invention and arranged for Warren to demonstrate the prototype in the UK.
The ARL assigned an engineering team to help Warren develop the prototype to the airborne stage. The team, consisting of electronics engineers Lane Sear, Wally Boswell, and Ken Fraser, developed a working design that incorporated a fire-resistant 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, made by the British firm of S. Davall & Sons Ltd, in Middlesex, was named the "Red Egg" because of its shape and bright red color.
The units were redesigned in 1965 and relocated at the rear of aircraft to increase the probability of successful data retrieval after a crash.
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
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" 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" 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 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 of all sounds which could be overheard in the cockpit.
On November 1, 1966, the director of the Bureau of Safety of the Civil Aeronautics Board Bobbie R. Allen and the chief of Technical Services Section John S. Leak presented "The Potential Role of Flight Recorders in Aircraft Accident Investigation" at the AIAA/CASI Joint Meeting on Aviation Safety, Toronto, Canada.
Terminology
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."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.