The box that records
The flight recorder is commonly called the black box, although it is painted bright orange so that it can be found in wreckage. Its purpose is to keep a record of what happened in the minutes before an accident, when no one survives to describe it.
The idea came in the 1950s from David Warren, a scientist at the Aeronautical Research Laboratories in Melbourne, who had been asked to help investigate the loss of Comet aircraft. He imagined a device that would record voices in the cockpit and the readings of the instruments, and he built a prototype in 1956. Officials at first were not enthusiastic. Pilots were uneasy about being recorded, and the authorities saw little use for it.
From curiosity to rule
Interest grew when it was demonstrated to British and American visitors. In the 1960s flight data recorders and cockpit voice recorders became compulsory in a growing number of countries. The units are built to survive impact, fire and deep water, and they carry a locator beacon that sends a signal from the sea bed for about a month.
The data from recorders has been used in investigations for decades, and the findings have changed procedures, equipment and training. A large part of today's safety record comes from reading what these small boxes have said.