With the ongoing search for Flight 370, much attention has been focused on how such flights are monitored. During this blog, we will trace the history of flight recorders from their earliest days to the technology of today’s systems.
The earliest attempt to develop a practical flight recorder was the result of experiments conducted by two French engineers in 1939. This recorder utilized a photographic film media to record changes in the aircraft’s attitude, such as diving, climbing, banks, turns and other variances by a projected beam of light. Although the system was limited by changing film strips after each flight, it served as the forerunner for future research. The development of flight recorders received a low priority during World War II as a result of military technology applications. However, two British scientists produced a device in 1945 which used a copper foil to record flight data, with various styli indicating the application of various aircraft controls. This system was both more practical and survivable than the film device and was relatively crash-proof for its time.
By the 1950s, flight recorders were enclosing in fire-proof casings. While the foil recording media was believed to be indestructible at the time, several high-profile crashes of the BOAC Comet jetliner proved the media vulnerable to a crash. In 1965, the FAA mandated flight recorder boxes withstand a 1,000 g. crash, from the prior standard of 100 g. of the 1950s. Also during that year, cockpit flight recorders were mandated which recorded the last thirty minutes of flight crew conversation. Initially, two separate recorders were installed, but a large number of combination recorders became available within a few years. While flight recorder boxes were black, dating from the film technology days, they were mandated to be bright red/orange color beginning in 1965, to make them more visible to rescue crews. Recorder boxes also began to be located in the tail of an aircraft, as a result of a number of crash tests, which proved the speed of impact to be drastically reduced by the time it reached the tail of the plane.
Because of the limitations of the foil system, magnetic tape became available in the late 1960s, in which ever larger amounts of flight data could be more easily recorded and stored. In the 1970s, the magnetic tape system became enhanced by the application of digital technology, which increased the speed by which flight data could be retrieved. By 1990 all of the major airlines began to use solid state flight recorders. A solid state system is one in which data is stored in semiconductor memories or integrated circuits, rather than using the older technology of electromechanical data retention. The advantages of the solid state system were low maintenance costs, as well as speed of data retrieval and ease of storage. Within a few years, it may be possible to develop a solid state video flight recorder to monitor all flight crew activities from the start of a flight to its finish. While some in the aviation community may view this as an intrusion, others will be glad big brother is watching.