PASSENGER aircraft could soon be equipped with an instrument that warns
pilots if they are heading for an engine-clogging cloud of ash from an erupting
volcano. Volcanic ash can be a major hazard to aircraft, according to engineers
at the Australian research organisation CSIRO. Ash clouds contain abrasive
silica particles but are invisible to radar. To date, says CSIRO, Boeing 747s
alone have suffered damage estimated at $80 million after flying into ash
clouds.
The detector has been a long time coming: the idea was hatched a decade ago
(麻豆传媒, 27 July 1991, p 23) but it has only just become a reality.
Costing A$100,000 (拢35,000) and no bigger than a Thermos flask,
CSIRO鈥檚 detector should give pilots up to 10 minutes鈥� warning of an ash
cloud鈥攎ore than enough to take evasive action.
The detector鈥檚 infrared sensor points straight ahead of the plane and is
fitted with a multiple-wavelength filter. Its output is fed to a processor that
can distinguish the spectral signature of silicate-laden ash from that of a
water-bearing cloud.
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鈥淭here have been a lot of incidents in the past where one, two or even four
engines have been lost,鈥� says CSIRO鈥檚 Fred Prata. The result is often a
terrifying dive that lasts several minutes before engines clear of ash and can
be restarted.