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A flight data recorder, or FDR, is one of two flight recorders ("black boxes"), used to record pilot input and aircraft parameters for the purpose of investigation of accidents and incidents.

A flight data recorder (FDR) is one of two major types of (popularly, though inaccurately, known as "black boxes"; the flight recorders are actually bright orange, to make them easier to find following a crash), used to record aircraft parametric data for purposes; the other flight recorder is the , which records cockpit audio.

The first FDRs were developed during World War II, and were used to record data during ; FDRs became available for s in the 1950s, and were made mandatory for large airliners in most countries (starting with ) in the 1960s, following a number of crashes where the lack of flight recorders significantly hampered the investigation process. For several decades, most FDRs recorded only five parameters - , indicated , magnetic , vertical acceleration, and microphone keying (to allow the FDR recording to be synchronised with the CVR recording) - plus a time signal. However, beginning in the 1970s and 1980s, manufacturers started to include more and more parameters in FDR recordings, and governmental were updated to require more and more of these additional parameters in addition to the basic five. As an example, current require FDRs to record 88 different parameters, and the FDRs on most newer aircraft go far beyond this, recording hundreds or even thousands of parameters.

Some newer recorders store both parametric and audio data in a single memory module (but still have two separate recorders); this provides redundancy, as, even if one recorder is lost or destroyed, all audio and parametric data can still be recovered from the other recorder. Such a combined FDR/CVR is known as a cockpit voice and data recorder, or CVDR.

There have been five main types of FDR over the years, distinguished by the medium used to record the data:

  • The first FDRs used photographic film, which could be easily read but was fragile and single-use-only; this limited their use to test flights and other one-off applications.
  • Some early commercial FDRs recorded data on magnetic wire, which was much more durable and could be reused, but never became very popular due to the difficulty in working with it.
  • The first FDR technology to become widely successful used movable styli to etch data traces into a long strip of heat-resistant metal foil; this was the gold standard for FDRs for decades, due to its durability and ability to record data from large numbers of flights before needing replacement, but eventually fell out of use due to only a small number of parameter traces fitting on the strip of foil.
  • Later FDRs used magnetic tape, which supported larger numbers of parameters and could be reused indefinitely, but had the disadvantages of a shorter recording time and being bulky and relatively fragile.
  • FDRs using solid-state flash memory first became available in 1990, and are now used in almost all new installations; these recorders can store an enormous amount of data in a very small memory chip, allowing this "memory module" to be made smaller and lighter and have more layers of shielding around it, and yet still store data from hundreds to thousands of parameters over hundreds of flights.

For more information about flight data recorders, see Wikipedia.