On the news recently I heard of yet another search for the black box flight-data recorder from a missing aircraft. Why is this data not transmitted periodically to a satellite or ground station so that in the event of the unexplained loss of an aircraft, it would be readily available?
• Early flight data was recorded on photographic film that had to be housed in a box into which light could not penetrate. This is the likely origin of the term “black box” recorder.
The black box now comprises the flight-data recorder and the cockpit voice recorder. There are also calls for the addition of a cockpit image recorder, which would record the external readings of the instruments and therefore what the flight crew actually sees.
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David Warren was the first to develop a prototype of a combined data and voice recorder in 1957. As a research scientist at the in Melbourne, Australia, he helped to investigate a series of fatal accidents involving the De Havilland DH106 Comet in 1953 and 1954.
He recognised that access to a recording of what had happened in the aircraft before the crashes would have been invaluable. He recalled seeing the first miniature recorder at a trade fair and this inspired his black box. ARL assigned him the resources to turn his prototype into an airworthy instrument.
“Australia was the first nation to make aircraft black boxes compulsory, others followed suit”
The aviation community gave the black box a largely lukewarm reception at first, until the crash of a Fokker Friendship at Mackay in Queensland, Australia, in 1960. This prompted Australia to make the black box recorder compulsory, and other aviation authorities followed suit.
According to the , about 2300 commercial airliners have suffered a breach of their fuselage, known as a hull breach, since then. As well as crashes and mid-air collisions, airliners have been shot down, or been the target of terrorist bombs and hijackings. The average number of hull breaches is now about 30 a year.
Of course there are instances where the cause of a crash is still uncertain even when the black box is recovered, but investigators have failed to recover the black box in only 10 hull-breach incidents, which equates to less than 0.5 per cent of crashes.
As well as recording flight data to a black box, limited data is transmitted. However, communication with ground stations is sometimes lost, and even transmission to satellites is not perfect.
Even when encrypted, there is always the worry that transmitted data could be hacked, redacted or lost before it reaches accident investigators. Airlines might object to the cost of continuously transmitting data, set against the tiny chance of crashing and then failing to recover the black box.
More importantly, to improve the chances of recovering black boxes at sea they could be designed to be buoyant or to transmit a signal to be picked up by hydrophones.
Mike Follows, Willenhall, West Midlands, UK