# NTSB ANC90FA020: Boeing 747-400, Anchorage, AK, December 15, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: December 15, 1989, 11:48 local (15:48 UTC)
- Place: Anchorage, AK
- Coordinates: 61.160522, -149.989074 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=61.1605&lon=-149.9891&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 245 uninjured
- Status: Completed, report June 30, 1992
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5278
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC90FA020
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5278/pdf
- Page: https://openairdocs.org/ntsb/ANC90FA020

## 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.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight encounter with weather, descent - normal
  - weather condition - clouds
  - weather condition - sand/dust storm (cause)
  - in flight weather avoidance assistance - attempted, atc personnel(artcc)
  - information insufficient (contributing factor)
- Loss of engine power, other
  - all engines
  - compressor assembly - foreign object (cause)
  - compressor assembly - stall (cause)
- Airframe/component/system failure/malfunction, descent
  - fuselage - eroded
  - wing - eroded
  - window,cabin - eroded
  - nacelle/pylon - eroded

## Analysis

BFR TKOF, CREW OF KLM FLT 867 ADZD OF VOLCANIC ERUPTION ABT 100 MI SW OF DESTN. EN ROUTE, FLT ADZD OF ANOTHER ERUPTION. FOR ARR, FLT CLRD TO DSCND FM FL390 AT PLT'S DISCRETION; VCTR GIVEN TO AVOID LAST KNOWN AREA OF ASH CLD. DRG DSCNT THRU FL260, FLT ENCTRD ASH CLD; ASH/SMOKE ENTERED COCKPIT/CABIN. CREW DONNED O2 MASKS; USED MAX PWR TO CLB. 1 MIN LTR, ALL ENGS LOST PWR (TO 28%-30% RPM); THERE WAS ELEC PWR INTRPN, LOSS OF AIRSPD INDCN, FIRE WARNING ALARM FOR FWD CARGO AREA. AFTER 8-9 ATMTS & DSCNT TO 13,300', ALL ENGS RESTARTED & FLT CONTD TO SAFE LDNG. DMG FND ON EXTERNAL SFCS OF ACFT & IN HI PRES TURBINES OF ALL ENGS. BOEING OMB #747-B2-4, ADZD TO AVOID VOLCANIC ACTIVITY; BUT IF ENCTRD, RETARDING THRUST TO IDLE WLD RDC BLDUP IN ENG & IMPROVE STALL MARGIN. ATC RADAR COULD ONLY DETECT VOLCANIC ASH FOR 5-10 MIN AFTER ERUPTION; ACFT RADAR NOT DESIGNED TO DETECT ASH. ASH CLD FCST TO MOV NNE AT 60 KTS; REVIEW OF SATELLITE DATA SHOWED IT ACTUALLY MOVED AT ABT 120 KTS. KLM HAD NO PROC FOR 747 ENCTR WITH ASH CLD & NO ADNL INSTRNS WERE GIVEN TO KLM CREWS.

## Aircraft

- Registration: PHBFC (not matched to a registry record)
- Reported make and model: BOEING 747-400
- Category: Airplane
- Serial number: 23982
- Airframe hours: 7050
- Engines: GE CF6-80C2 57180 lbs thrust turbo fan
- Damage: Substantial damage
- Flight: Part 129
- Registered owner: Klm Royal Dutch Airlines
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, November 24, 1989, 227 hours before
- Departed: EHAM, AMSTERDAM, OF
- Destination: ANC, ANCHORAGE, AK
- Flight plan: IFR
- Airport: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 51; airline transport, foreign; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: rear; flight hours: 13,000 total, 100 in this make and model, 100 in the last 90 days, 25 in the last 30 days, 9 in the last 24 hours

## Weather

- Conditions: Instrument (IMC), Day
- Wind: 50° at 7 knots
- Lowest ceiling: 8,000 ft overcast
- Temperature: 32 °F, dew point 25 °F
- Altimeter: 30.00 inHg
- Observed at: TKA, 25 nm away

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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