Narrative:At FL250 the aircraft flew into a normal looking cloud, which turned out to be a volcanic ash cloud (the result of an eruption of Mount Redoubt). Power was added to climb out of the cloud. About 10-15 seconds later all 4 engines failed and the standby electrical system failed. The crew were able to restart the engines after numerous attempts. The no. 1 and 2 engines were relit while descending through FL130 and the remaining 2 engines were relit at FL110. The aircraft landed safely at Anchorage, substantially damaged by the in-flight blasting by volcanic ash. The windshields were damaged, as were internal aircraft systems, avionics and electronics.
Probable Cause:
PROBABLE CAUSE: "Inadvertent encounter with volcanic ash cloud, which resulted in damage from foreign material (foreign object) and subsequent compressor stalling of all engines. A factor related to the accident was: the lack of available information about the ash cloud to all personnel involved."
Accident investigation:
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Investigating agency: | NTSB |
Status: | Investigation completed |
Duration: | 2 years and 7 months | Accident number: | ANC90FA020 | Download report: | Final report
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Classification:
Ash cloud
Forced landing on runway
Sources:
» NTSB
Photos
accident date:
15-12-1989type: Boeing 747-406
registration: PH-BFC
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does
not display the exact flight path.
Distance from Amsterdam-Schiphol International Airport to Anchorage International Airport, AK as the crow flies is 7147 km (4467 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.