FLIGHT DATA RECORDER

The flight data recorder (FDR) refers generically to a class of recorders used to record specific aircraft performance parameters. A separate device is the cockpit voice recorder (CVR), although some recent types combine both in one unit. Popularly known as the black box used for aircraft mishap analysis, the FDR is also used to study air safety issues, material degradation, and jet engine performance. These ICAO regulated "black box" devices are often used as an aid in investigating aircraft mishap, and these devices are typically one of the highest priorities for recovery after a crash, second only to bodies of victims. The device's shroud is usually painted bright orange and is generally located in the tail section of the aircraft.

HISTORY

The first prototype FDR was produced in 1957 by Dr David Warren of the then Aeronautical Research Laboratories of Australia. In 1953 and 1954, a series of fatal mishaps on 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 no witnesses, and no survivors, Dr Warren began to conceive of a crash survivable method to record the flight crew's conversation, reasoning they would likely know the cause.

Despite his 1954 report entitled "A Device for Assisting Investigation into Aircraft Accidents" and a 1957 prototype FDR named "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, became interested. Dr Warren was asked to create a pre-production model which culminated into the "Red Egg", the world's first commercial FDR by the British firm, S. Davall & Son. The "Red Egg" got its name from the shape and bright red color. Incidentally, 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."

DESIGN

The design of today's FDR is largely governed by the European Organisation for Civil Aviation Equipment in its EUROCAE ED-122 (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, TSO-C124a, which mostly refers back to ED-122 (like many other countries' aviation authorities).

Currently, EUROCAE specifies that a recorder must be able to withstand an acceleration of 3400 g (33 km/s²) acceleration for 6.5 milliseconds. This is roughly equivalent to an impact velocity of 270 knots and a deceleration or crushing distance of 450 mm. 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 are typically plugged into the aircraft's fly-by-wire main data bus. 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 by 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 faster frequency if the data begins to change quickly. Most FDRs record more than a day's worth of data.

Recently aviation authorities have begun to place FDRs in the empennage. 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. Additionally, since the recorders are sometimes crushed into unreadable pieces, or never located, some modern units are self-ejecting, with radio and sonar beacons (i.e. emergency locator transmitter).

Smiths Aerospace Crash Protected Recorders