Aviation Accident Summaries

Aviation Accident Summary ANC13LA100

Kotzebue, AK, USA

Aircraft #1

N8316Q

CESSNA U206F

Analysis

Before departing from a remote hunting site on a short cross-country flight, the accident pilot obtained a pilot report from another pilot who had just flown the route. The pilot report indicated 25 miles visibility, clouds at 1,400 feet, and a cloud ceiling at 1,800 feet. The airplane departed uneventfully, and, about 15 minutes into the 30-minute flight, the airplane approached the last ridge before the destination airport. The top of the ridge was about 1,950 feet mean sea level. The pilot stated that the destination airport peninsula was visible in the distance with an estimated 500 feet of clearance between the top of the ridge and the base of the cloud ceiling. He added that, as the airplane neared the ridge, the airplane encountered a severe downdraft and an abrupt entry into instrument meteorological conditions and then subsequently collided with the ridge about 30 to 50 feet below the ridgeline. However, review of handheld GPS data revealed that the airplane was in a constant climb during the minutes leading up to the collision with the ridge except for a 6-foot descent just before the collision. Additionally, the nearest reporting weather station reported a cloud ceiling about 50 feet below the ridgeline. The pilot noted no preimpact mechanical malfunctions with the airplane that would have precluded normal operation. Thus, it is likely that the pilot was flying the airplane low to stay below the clouds and then began to climb the airplane to clear the ridge when he entered instrument meteorological conditions as the airplane approached the ridge.

Factual Information

On September 13, 2013, about 1315 Alaska daylight time, a Cessna U206F airplane, N8316Q, operated by a private individual, was substantially damaged when it collided with mountainous and hilly terrain about 25 miles northeast of Kotzebue, Alaska. The commercial pilot and passenger were seriously injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the planned flight to Ralph Wien Memorial Airport, Kotzebue, Alaska. No flight plan was filed for the flight that departed from a remote hunting camp near Kiana, Alaska, about 1300. The pilot stated that the purpose of the accident flight was to get supplies at Kotzebue and return to the hunting camp. Prior to departure, he obtained a pilot report from another pilot that had just flown the route. The pilot report included visibility 25 miles, clouds at 1,400 feet, and a ceiling at 1,800 feet. The accident airplane departed uneventfully and was in cruise flight as it approached the last ridge before Kotzebue. The pilot further stated that the Kotzebue peninsula was visible in the distance with an estimated 500 feet of clearance, between the top of the ridge and the base of the cloud layer. The pilot added that as the airplane neared the ridge, a severe downdraft was encountered along with abrupt entry into instrument meteorological conditions. He stabilized the airplane using cockpit instrumentation; however, the airplane collided with the ridge about 30 to 50 feet below the ridgeline. The pilot also noted that there were no preimpact mechanical malfunctions with the airplane. A handheld GPS was recovered from the airplane and forwarded to the NTSB Vehicle Recorders Laboratory, Washington, DC, for data download. Review of the downloaded data revealed that during the last 6 minutes of flight, the airplane climbed from a GPS altitude of 709 feet to a GPS altitude of 1,955 feet. During the last 1 minute of flight, as the airplane approached the ridge, it climbed from a GPS altitude of 1,562 feet, to a GPS altitude of 1,955 feet. One second later, the airplane descended 6 feet to a GPS altitude of 1,949 feet, followed by a 10-foot descent to 1,939 feet 8 seconds after; however, the groundspeed between those two records decayed from 53 knots to 12 knots, consistent with collision occurring during that time. After learning about reports of a weak emergency locator transmitter signal north of Kotzebue, search and rescue personnel aboard an Army National Guard UH-60L helicopter were dispatched from Nome, Alaska. The two seriously injured occupants remained at the accident site, while pinned in the wreckage, for approximately 28 hours before rescue personnel could reach the accident site. The closest weather reporting facility was at Kotzebue, about 25 miles southwest of the accident site. At 1253, a weather observation was reporting, in part: Wind from 230 degrees at 17 knots; visibility 9 miles in light rain, broken ceiling at 1,900 feet, overcast ceiling at 2,500 feet; temperature 6 degrees C; dew point 3 degrees C; altimeter 29.81 inches Hg. At 1353, a weather observation was reporting, in part: Overcast ceiling at 1,700 feet.

Probable Cause and Findings

The pilot’s improper decision to continue visual flight rules flight into instrument meteorological conditions, which resulted in controlled flight into terrain.

 

Source: NTSB Aviation Accident Database

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