FLIGHT recorders for all civil aircraft built after 2004 will have back-up
power supplies built in, air safety experts have decided. The move follows the
crash of a Swissair jet off Halifax, Nova Scotia, in September, in which the two
black boxes鈥攖he flight data recorder and the cockpit voice
recorder鈥攃ut out six minutes before impact. The investigation into the
crash, which killed 229 people, has been hampered by the lack of data on those
final minutes.
At present, all but the latest of the world鈥檚 12 000 civil airliners use
tape-based recorders that are powered by the aircraft鈥檚 generators, which in
turn are driven by the engines. But the recorders have no built-in back-up power
(This Week, 3 October, p 4).
Last week, the Flight Recorder Panel of the International Civil Aviation
Organization in Montreal announced that it has decided to 鈥渟upport the need for
an independent power source for flight recorders鈥�. The panel has still to work
out the technical details, but Peter Sheppard, head of the flight-recorder
section at Britain鈥檚 Air Accident Investigation Branch, and a member of the
panel, says that the independent power supply will have to last at least ten
minutes after a loss of external power. This will almost certainly require the
use of the new generation of microchip-based flight recorders, says Sheppard.
鈥淚ndependent power supplies will only be applicable to aircraft with solid-state
recorders, as they only require half the power of a tape recorder,鈥� he says.
Solid-state voice recorders will preserve two hours of cockpit activity, against
30 minutes with today鈥檚 tapes.
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Sheppard says that the problems of installing, maintaining and charging
batteries may steer the panel towards newer energy storage technologies:
鈥淭here鈥檚 a possibility that some new capacitor technology might fit the bill for
a ten-minute supply, but that鈥檚 only just been developed,鈥� he says. The panel鈥檚
proposals will now go to ICAO鈥檚 Air Navigation Commission for technical
evaluation.