Aviation Accident Summaries

Aviation Accident Summary ANC99LA023

CHEVAK, AK, USA

Aircraft #1

N19TA

Cessna 207

Analysis

The certificated commercial pilot reported that during his initial descent to the Chevak Airport, the airplane became 'heavy to control' while flying through snow showers mixed with rain. He stated that while on a left base for landing on runway 14, the airplane failed to respond to left control yoke movements. He said that he was able to turn the airplane slowly to the right, 270 degrees from his original heading, and align the airplane for landing on runway 14. He stated that while on short final over the threshold of the runway, he again applied left control yoke movement to correct for a 12 to 15 knot, left crosswind. The control movement again failed to have any effect, and the airplane drifted to the right, touched down to the right of the runway, and nosed over. The pilot stated that a postaccident inspection revealed ice formation on the airplane's wings, struts, and fuselage. The airplane sustained substantial damage to the wings and fuselage.

Factual Information

On January 12, 1999, about 1050 Alaska standard time, a wheel equipped Cessna 207 airplane, N19TA, sustained substantial damage during landing at the Chevak Airport, Chevak, Alaska. The airplane was being operated as a visual flight rules (VFR) on-demand cargo/U.S. mail flight under Title 14, CFR Part 135, when the accident occurred. The airplane was registered to, and operated by, Arctic Transportation Services, Inc., Anchorage, Alaska. The solo commercial pilot was not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated at the Bethel Airport, Bethel, Alaska, about 0947. In his written report to the National Transportation Safety Board, the pilot related that during his initial descent to the Chevak Airport, the airplane became "heavy to control" while flying through snow showers mixed with rain. He wrote: "I observed ice gathering on the struts, wings, and some on the windshield. With the plane feeling heavier, I started descending faster to try to get below the freezing level." He said that while on a left base for landing on runway 14, the airplane failed to respond to left control yoke movements. He said that he was able to turn the airplane slowly to the right, 270 degrees from his original heading, and align the airplane for landing on runway 14. He stated that while on short final over the threshold of the runway, he again applied left control yoke movement to correct for a 12 to 15 knot, left crosswind. The control movement again failed to have any effect, and the airplane drifted to the right, touched down to the right of the runway, and nosed over. The pilot stated that a postaccident inspection revealed ice formation on the airplane's wings, struts, and fuselage. The airplane sustained substantial damage to the wings and fuselage. The director of operations for the company wrote in the NTSB Pilot / Operator report, that weather conditions at the accident airport were, in part: Sky conditions and ceilings, 700 feet broken; visibility, 2-3 statute miles with rain and snow; wind, 050 degrees at 12 to 15 knots; temperature, 18 degrees F; altimeter, 28.96 inHg. Hooper Bay, Alaska, is located 18 miles west of the accident site. At 1151, an unaugmented AWOS was reporting, in part: Wind, 070 degrees (true) at 16 knots; visibility, 6 statute miles; clouds, 100 feet broken, 1,000 feet overcast; temperature, 19 degrees F; dew point, 15 Degrees F; altimeter, 28.68 inHg.

Probable Cause and Findings

The pilot's continued flight into adverse weather conditions. Factors associated with the accident were freezing rain, an accumulation of ice on the wings and ailerons, and diminished directional control.

 

Source: NTSB Aviation Accident Database

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