voice, and the noise of any aircraft structural components undergoing serious fracture and breakage) which could be overheard in the cockpit. 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 literally 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." (The term "black box" is used with a different meaning in science and engineering, describing a system exclusively by its inputs and outputs, with no information whatsoever about its inner workings.) 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. Components Flight data recorder A flight data recorder (FDR; also ADR, for accident data recorder) is an electronic device employed to record instructions sent to any electronic systems on an aircraft. The data recorded by the FDR are used for accident and incident investigation. Due to their importance in investigating accidents, these ICAO-regulated devices are carefully engineered and constructed to withstand the force of a high speed impact and the heat of an intense fire. Contrary to the popular term "black box", the exterior of the FDR is coated with heat-resistant bright orange paint for high visibility in wreckage, and the unit is usually mounted