NTSB Identification: ANC97FA031.
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Accident occurred Friday, March 07, 1997 in SITKA, AK
Probable Cause Approval Date: 05/29/1998
Aircraft: Buesing SX-300, registration: N357SX
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The homebuilt airplane was being operated as an IFR cross-country flight over mountainous/coastal terrain. While cruising at 14,000 ft, about 19 miles from the nearest airport, the pilot encountered a low engine power condition. He declared an emergency, & was given vectors to the airport. The airplane was capable of gliding about 24 miles from 14,000 ft, but was ditched in the ocean, about 5 miles from the airport. The occupants did not egress from the airplane before it sank. The airplane engine had a ram air/alternate air box attached to the fuel control servo which controlled the engine air source. Ram air was unheated & unfiltered, & was to be used when operating in clear/dry air conditions. Alternate air was heated & filtered, & was to be used during an engine emergency, takeoff & landing, when flying in dusty air, or when in conditions where inlet icing could be expected (visual moisture & temperatures of 40 deg F or below). The airplane's air control was found in the ram air position. Weather conditions near the accident site included a temperature & dew point of 35 deg with snow & ice pellets. Upper air conditions along the route of flight included temperatures between -28 to -45 deg C, & humidity levels between 69 & 81 percent. An AIRMET had been issued for the area. It included a caution for light & temporary moderate icing in clouds & in precipitation from 1,000 ft to 12,000 ft. The freezing level was 1,000 ft. The pilot was provided a PIREP that indicated a trace of ice had been encountered in the area.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot's failure to properly evaluate the presence of icing conditions, and his failure to comply with procedures to use alternate engine air in icing conditions. Factors relating to the accident were: icing (weather) conditions, the pilot's improper application of emergency procedures to maximize available glide distance, and the lack of suitable terrain for a forced landing. Full narrative available
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