Game Warden Had Flown Out To Assist A Colleague Who's Snowmobile Broke Down

The NTSB has issues a probable cause report in an accident in which a public use airplane went down in a snow squall in March of last year. The game warden/pilot had flown out to assist a colleague who's snowmobile had broken down on a frozen lake, and the weather deteriorated during the return flight. The investigation found no pre-impact mechanical difficulties with the aircraft, though the board said that it was unable to say for sure that all the instruments were working when the plane went down.

NTSB Identification: ERA11GA207
14 CFR Public Use
Accident occurred Thursday, March 24, 2011 in Ashland, ME
Probable Cause Approval Date: 04/02/2012
Aircraft: CESSNA A185F, registration: N724MT
Injuries: 1 Fatal.

The pilot was employed as a state game warden, and, on the day of the accident, he was on patrol in the ski-equipped airplane when he received a radio call from another game warden whose snowmobile was stuck on a nearby frozen lake. After landing on the lake and assisting another game warden, the pilot departed on the accident flight, presumably to return to his home base.

The other game warden reported that, immediately after the airplane departed, the visibility was reduced to less than 1/2-mile due to snow. Postaccident analysis of position information recovered from a portable global positioning system (GPS) receiver showed that the airplane flew for about 10 minutes after takeoff at a relatively constant GPS altitude of about 1,500 feet mean sea level, or about 200 to 500 feet above ground level (agl). Shortly before the accident, the airplane turned left, away from its previously established course, toward a frozen lake along the route. During the final moments of the flight, the airplane entered a right descending turn from about 300 feet agl. During this time, the airplane was in an estimated 40-degree right bank, and its descent rate increased to in excess of 3,000 feet per minute.

Examination of the accident site revealed ground scars and airplane damage consistent with the established descent profile continuing to impact. Examination of the wreckage revealed no evidence of any preimpact mechanical malfunctions or failures, although the definitive operational status of the vacuum-driven instruments could not be determined. Analysis of weather information and witness statements were consistent in depicting conditions likely to have produced restricted visibility and possible whiteout conditions in a snow squall over the area at the time of the accident. These restricted visibility conditions would have been conducive to the development of spatial disorientation, and the airplane’s turning ground track and rapid descent were consistent with the pilot losing control of the airplane due to spatial disorientation.

The National Transportation Safety Board determined the probable cause(s) of the accident to be an inadvertent encounter with localized instrument meteorological conditions, which resulted in spatial disorientation and a loss of control.

FMI: www.ntsb.gov