User:Lissajous/FDR

An aircraft flight recorder facilitates the investigation of an aircraft accident or incident by providing a durable record of events.

For this reason, recorders are required to be capable of surviving the conditions likely to be encountered in a severe aircraft accident. They are typically specified to withstand an impact of 3600 g and temperatures of over 1,000 °C (as required by EUROCAE ED-112). There are two common types of flight recorder, the flight data recorder (FDR) and the cockpit voice recorder (CVR). In some cases, the two recorders may be combined in a single FDR/CVR unit.

History
As with many successful devices, probably no single person could be credited with the invention of the flight 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; they were essentially photograph-based flight recorders since the record was made on a scrolling 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). Since the inside of the recorder was pitch black, this may be the origin of the "black box" name, often used as a synonym for a flight recorder. 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"; the SFIM went on becoming a successful equipment company and a major flight recorder supplier, and is today part of the Safran group. In 1953, Australian engineer David Warren conceived a device that would record not only the instruments reading, but also the cockpit voices, when working with the Aeronautical Research Laboratory (Melbourne, Australia). He built the first prototype in 1958. It wasn't until after the 1956 Grand Canyon mid-air collision that black boxes of any kind were installed on commercial airplanes. In 1965 black boxes were redesigned and moved to the rear of airplanes to improve the probability of successful data retrieval after a crash.

History
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). 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. 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. 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.

thumb|right|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.

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. 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.

Specifications
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. When issued in March 2003 ED-112 superseded previous ED-55 and ED-56A that were separate specifications for FDR and CVR. FAA TSOs for FDR and CVR reference ED-112 for characteristics common to both types.

In order to facilitate recovery of the recorder from an aircraft accident site they are required to be coloured bright yellow or orange with reflective surfaces. All are lettered "FLIGHT RECORDER DO NOT OPEN" on one side in English and the same in French on the other side. To assist recovery from submerged sites they must be equipped with an underwater locator beacon which is automatically activated in the event of an accident.

Cockpit image recorder recommendation
The U.S. National Transportation Safety Board 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 also recommended image recorders be placed into smaller aircraft that are not required to have a CVR or FDR. The rationale is that what is seen on an instrument by the pilots of an aircraft is not necessarily the same as the data sent to the display device. This is particularly true of aircraft equipped with electronic displays (CRT or LCD). A mechanical instrument is likely to preserve its last indication but this is not the case with an electronic display.

Such systems, estimated to cost less than $8,000 installed, typically consist of a camera and microphone located in the cockpit to continuously record cockpit instrumentation, the outside viewing area, engine sounds, radio communications, and ambient cockpit sounds. As with conventional CVRs and FDRs, data from such a system is stored in a crash-protected unit to ensure survivability.

Flight data 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.

XXXX: Parameters which the FAA requires (see BOEING) str:
 * Time.
 * Altitude.
 * Airspeed.
 * Vertical acceleration.
 * Heading.
 * Time of each radio transmission either to or from air traffic control.
 * Pitch attitude.
 * Roll attitude.
 * Longitudinal acceleration.
 * Control column or pitch control surface position.
 * Thrust of each engine.

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/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 6000 m.

Quick Access Recorder
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 of the requirement that they survive an accident. They also require specialist 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.

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.

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. Therefore, they have the potential for exposing military secrets if the device is captured by non-friendly forces and exploited

General information

 * &mdash; University of Minnesota article on the legacy of James "Crash" Ryan
 * How Black Boxes Work &mdash; Detailed seven page article from HowStuffWorks
 * IRIG 106 Chapter 10 &mdash; Flight data recorder digital recorder standard
 * IRIG 106 Chapter 10 &mdash; Flight data recorder digital recorder standard

Dr David Warren

 * Dave Warren - Biography, Australian Government, Department of Defence
 * David Warren - Inventor of the Black Box Flight Recorder
 * ABC TV (Australia) Dr David Warren interview transcript 2003
 * ABC TV (Australia) Dr David Warren interview transcript 2002
 * 'The ARL ‘Black Box’ Flight Recorder' &mdash; Melbourne University history honours thesis on the development of the first flight recorder by David Warren