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Flight data recorder
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The flight data recorder (FDR) (also ADR, for Accident Data Recorder) is a device used to record specific aircraft performance parameters. A companion device 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.
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The flight data recorder (FDR) (also ADR, for Accident Data Recorder) is a device used to record specific aircraft performance parameters. A companion device 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, as was the case with the original design.
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.
History
The first prototype FDR was produced in 1956 by Dr. David Warren of the then Aeronautical Research Laboratories of Melbourne, Australia. 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.
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", the world's first commercial FDR, made by the British firm of S. Davall & Son. The "Red Egg" got its name from its shape and bright red
color.
The term "Black Box" came from a meeting about the "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.
Design
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 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, based on the EUROCAE documents (as do the aviation authorities of many other countries).
Currently, EUROCAE specifies that a recorder must be able to withstand an acceleration of 3400 g (33 km/s˛) 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.
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 acts 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.
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. One problem for the military is that these commercial devices offer no protection of the data that has been recorded thus have the potential for exposing military secrets if the device is captured by non-friendly forces and exploited.
See also
External links
Manufacturers
General information
- — University of Minnesota article on the legacy of James "Crash" Ryan
- — Australian Department of Defence article on the flight recorder
- — Melbourne University history honours thesis on the development of the first flight recorder by David Warren
- — Australian Department of Defence article on the flight recorder's inventor
- — Detailed seven page article from HowStuffWorks
- — Flight data recorder digital recorder standard
Dr David Warren
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