A brief history of the flight recorder

A beam of light at Marignane

Around 1939, at Marignane, the engineer François Hussenot and his associate Beaudouin built a recorder that wrote flight parameters with light: a mirror deflected a thin beam onto photographic film eight metres long. The device, known as the type HB after their initials, and nicknamed the hussenograph, was made to analyse test flights rather than accidents. Hussenot co-founded SFIM in 1947 to build such instruments, a company later absorbed into Safran. He died in 1951, in the crash of a test flight.

Foil, wire and the 1950s

The 1950s gave the recorder its modern shape. In the United States, James Ryan of General Mills filed a patent in 1953 for a recorder whose styli embossed altitude, airspeed, vertical acceleration and time onto aluminium foil: the VGA recorder, for velocity, g and altitude. In Australia, David Warren of the Aeronautical Research Laboratories, struck by the unexplained airliner losses of the time, proposed in 1954 to record the crew's voices as well. By 1958, his ARL Flight Memory Unit stored four hours of cockpit sound and instrument readings on steel wire, overwriting itself in a loop.

Regulation follows the accidents

• United States, 1957 and 1958: a rule adopted in 1957 required, from 15 July 1958, a flight data recorder on aeroplanes over 12,500 lb certificated to fly above 25,000 ft, recording time, airspeed, altitude, vertical acceleration and heading.
• United States, 1964 to 1967: the cockpit voice recorder rule, adopted in 1964, applied from 1966 to large turbine aircraft, with a 30-minute memory.
• Australia, among the first countries to require voice recording, after the inquiry into an accident at Mackay in 1960 recommended recorders.
• United Kingdom: requirements phased in from 1965.

From foil to solid state

Foil was robust but crude: a handful of parameters scratched onto a strip. Digital flight data recorders on magnetic tape appeared in the early 1970s, holding 25 hours, and voice recorders used tape loops of 30 minutes. In 1987, the United States ordered the last foil recorders replaced by digital ones by 1995, after investigators found that nearly half of the foil recorders they examined had malfunctioning parameters. Solid-state memory arrived around 1990, and with it the two-hour voice recorder and the end of moving parts in the protected memory.

The European standards

After AF447 and MH370

Two accidents of this century changed the rules once more. Air France 447 disappeared over the Atlantic on 1 June 2009, and its recorders were recovered nearly two years later. Investigators recommended longer-lasting beacons, an extra low-frequency beacon, and ways to get data off an aircraft before it is lost. Since 1 January 2018, ICAO has required recorder beacons that last 90 days and, on aeroplanes over 27,000 kg, an 8.8 kHz locator fixed to the airframe.

Malaysia Airlines MH370, lost on 8 March 2014 and never found, led to aircraft tracking at least every fifteen minutes and, for new aircraft types, the timely recovery of flight data: by transmission, or by a recorder that separates from the aircraft and floats. Voice recording grew longer too. The ICAO 25-hour cockpit voice recorder applies to aeroplanes over 27,000 kg first certified from 1 January 2022, and the United States adopted its own 25-hour rule in February 2026 for newly built airliners.

Why "black box"?

Nobody knows for certain. The most documented explanation is the slang of the 1940s, in which any sealed electronic unit was a black box. Whatever its origin, the name stuck to a box that has been orange for decades: the rules require a distinctive bright colour and reflective strips, so that it can be found in wreckage or under water.