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Last updated: 26 January 2022
Status:Definitief
Datum:woensdag 25 september 1985
Tijd:13:33
Type:Silhouette image of generic B732 model; specific model in this crash may look slightly different
Boeing 737-2X6C
Luchtvaartmaatschappij:MarkAir
Registratie: N674MA
Constructienummer: 23292/1113
Bouwjaar: 1985-05-06 (5 months)
Aantal vlieguren:614
Motoren: 2 Pratt & Whitney JT8D-17A
Bemanning:slachtoffers: 0 / inzittenden: 4
Passagiers:slachtoffers: 0 / inzittenden: 17
Totaal:slachtoffers: 0 / inzittenden: 21
Schade: Groot
Gevolgen: Repaired
Plaats:Unalaska Airport, AK (DUT) (   Verenigde Staten)
Fase: Landing (LDG)
Soort vlucht:Binnenlandse lijnvlucht
Vliegveld van vertrek:Anchorage-Ted Stevens International Airport, AK (ANC/PANC), Verenigde Staten
Vliegveld van aankomst:Unalaska Airport, AK (DUT/PADU), Verenigde Staten
Vluchtnummer:AS71
Beschrijving:
The Boeing 737-200 aircraft was dispatched to a restricted airport with a 3900 ft runway and notamed: 3 inch standing water on north end of runway. A sigmet was in effect for moderate to severe turbulence below 10,000 feet due to strong low level wind and associated windshear. The captain made a shallow overwater approach to runway 12, which had a near vertical 70 ft bluff skirting its left edge, approx 106 feet from the runway centerline. On final approach, the captain noted variable wind conditions and a sudden 15 kt increase in IAS due to windshear. He continued the approach, but the aircraft settled and touched down 72 feet short of the runway. The left hand main gear hit a log that was washed onto shore and a large rock, then collapsed after the aircraft bounced and landed on the runway. Unpredictable winds and downdrafts were reportedly prevalent at this airport.
Official 13:49 ADT wind was from 160 degrees at 8 kts, but at the approach end of runway, wind was reported coming over the bluff and was gusty. The FAA had granted MarkAir exemption to operate at Unalaska without overrun/safety areas. There was also no VASI at the approach end of runway 12. The owner (State of Alaska) delayed improvements due to funding problems. This was the captain's 10th landing at Unalaska. The required dry landing field length was computed to be 3700 feet.

Probable Cause:

PROBABLE CAUSE(S):
planning/decision..improper..company/operator management
compensation for wind conditions..inadequate..pilot in command
proper touchdown point..not attained..pilot in command

CONTRIBUTING FACTORS:
insuff standards/requirements,operation/operator..FAA(organization)
airport/facilities..inadequate
other airport/runway maintenance..inadequate
inadequate surveillance of operation..FAA(organization)
inadequate surveillance of operation..other govt organization
light condition..sunglare
visual/aural perception..pilot in command
airport facilities,visual apch slope ind(vasi)..unavailable
weather condition..unfavorable wind
weather condition..windshear
lack of familiarity with geographic area..pilot in command
terrain condition..rough/uneven
terrain condition..loose objects

Bronnen:
» NTSB


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Kaart
Deze kaart geeft het vliegveld van vetrek weer en de geplande bestemming van de vlucht. De lijn tussen de vliegvelden geeft niet de exacte vliegroute weer.
De afstand tussen Anchorage-Ted Stevens International Airport, AK en Unalaska Airport, AK bedraagt 1261 km (788 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.
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