PH-BFC from Flight 867 |
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| Incident summary | |
|---|---|
| Date | 15 December 1989 |
| Type | Failure of all engines due to blockage by volcanic ash |
| Site | Redoubt Volcano, Anchorage, Alaska |
| Passengers | 231 |
| Crew | 14 |
| Injuries | 0 |
| Survivors | 245 (all) |
| Aircraft type | Boeing 747-406M |
| Operator | KLM |
| Tail number | PH-BFC |
| Flight origin | Amsterdam Airport Schiphol |
| Destination | Narita International Airport |
On 15 December 1989, KLM Flight 867 en route to Narita International Airport, Tokyo from Amsterdam was descending into Anchorage International Airport, Alaska when all four engines failed. The Boeing 747-400, less than 6 months old,[1] flew through a thick cloud of volcanic ash from Mount Redoubt,[2] which had erupted the day before.
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All four engines failed leaving only critical systems on backup electrical power. One report assigns the engine shutdown to the turning of the ash into a glass coating inside the engines that fooled the engine temperature sensors and led to an auto-shutdown of all four engines.[3]
When all four main generators shut off due to the failure of all the engines, a momentary power interruption occurs when the flight instruments transfer to standby power. Standby power on the 747-400 is provided by two batteries and inverters. The captain performed the engine restart procedure which was not successful on the first few attempts and was repeated until restart was achieved. On some of the attempts, as one or more (but not all) engines started to operate, the main generator would switch back on. This switching on and off caused repeated power transfer interruptions to the flight instruments. The temporary blanking of the instruments gave the appearance that standby power had failed. These power transfers were later verified from the flight data recorder.
The following transmissions took place between Anchorage Center, the air traffic control facility for that region, and KLM 867:[4]
After descending more than 14,000 feet, Captain Karl van der Elst and crew were finally able to restart the engines and safely land the plane. In this case the ash caused more than US$80 million in damage to the aircraft (requiring all four engines to be replaced), but no lives were lost and no one was injured.[2] [5] As of 2011, the aircraft is still in service with KLM under the KLM Asia livery.[6]
Flight 867 now operates the Amsterdam-Osaka (Kansai) route.
In a nearly identical incident on 24 June 1982, British Airways Flight 9 from London Heathrow to Auckland, whilst on the sector from Kuala Lumpur to Perth, Western Australia, flew into a cloud of volcanic ash from the eruption of Mount Galunggung, causing all four engines to fail due to compressor stall. The aircraft was diverted to Jakarta, and was able to glide far enough to exit the ash cloud, restart its engines and land safely.[7]
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