patrick and linda asked:
hi bill,
thanks for the explanation. to your knowledge have there been any recorded plane accidents caused by the suspended fragments of glass?
pat
A long time ago, in a C-130 squadron far, far away, I was a Naval Flight Officer; Wings of Gold, Bars of Brass, you can shove them up your... but I digress.
:wink:
Volcanic ash can and has caused multiple engine failure in jet aircraft in cruise flight. The sandblasting effect can be quite severe, to the extent that seeing outside the cockpit can be problematic. See:
http://en.wikipedia.org/wiki/British_Airways_Flight_9
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British Airways Flight 9, sometimes referred to as the Speedbird 9 or Jakarta incident,[1] was a scheduled British Airways flight from London Heathrow to Auckland, with stops in Bombay, Madras, Kuala Lumpur, Perth, and Melbourne.
On June 24, 1982, the route was flown by City of Edinburgh, a 747-236B registered G-BDXH. The aircraft flew into a cloud of volcanic ash thrown up by the eruption of Mount Galunggung, resulting in the failure of all four engines, although the reason for the failure was not then apparent to the crew or ground control. The aircraft was diverted to Jakarta in the hope that enough engines could be restarted to allow it to land there. The aircraft was able to glide far enough to exit the ash cloud, and all engines were restarted (although one failed again soon after), allowing the aircraft to land safely.
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As Flight 9 approached Jakarta, the crew found it difficult to see anything through the windscreen, and had to make the approach almost entirely on instruments, despite reports of good visibility. The crew decided to fly the ILS, Instrument Landing System, however, the glideslope was inoperative, so they flew the localizer as the first officer monitored the airport's DME (Distance Measuring Equipment). He then called out how high they should be at each DME step along the final track to the runway, creating a virtual glide slope for them to follow. It was, in Moody's words, "a bit like negotiating one's way up a badger's arse".[1] Although the runway lights could be made out through a small strip of the windscreen, the landing lights on the aircraft seemed to be inoperable. After landing, the flight crew found it impossible to taxi, due to glare from apron floodlights which made the already sandblasted windscreen opaque. Therefore, City of Edinburgh had to wait for an airport tug to tow her in.
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It was found that City of Edinburgh's problems had been caused by flying through a cloud of volcanic ash from the eruption of Mount Galunggung. Because the ash cloud was dry, it did not show up on the weather radar, which is designed to detect the moisture in clouds. The cloud sandblasted the windscreen and landing light covers and clogged the engines. As the ash entered the engines, it melted in the combustion chambers and adhered to the inside of the power-plant. As the engine cooled from not running and as the aircraft descended out of the ash cloud, the molten ash solidified and enough broke off to allow air to flow smoothly through the engine allowing a successful restart. The engines had enough electrical power to restart because one generator and the onboard batteries were still operative; generator or battery power is required for ignition of the engines.
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A nearly identical incident occurred on 15 December 1989 when KLM Flight 867, a B747-400 from Amsterdam to Anchorage, Alaska, flew into the plume of the erupting Mount Redoubt, causing all four engines to fail due to compressor stall. Once the flight cleared the ash cloud, the crew was able to restart each engine and then make a safe landing at Anchorage. However, unlike City of Edinburgh, the aircraft was substantially damaged.
<SNIP>
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C-Dory content: Since C-Dory surface skimmers travel much more slowly than Boeing 747 jet aircraft in cruise flight, potential sandblasting effects are correspondingly reduced.
:lol:
Best regards,
:thup :smiled