Pilot Debrief

MAULE M-4-220C near Hungry Horse, MT — 2009-04-01

Final reportWPR09FA176
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Date
2009-04-01
Location
Hungry Horse, MT, USA
Airport
GPI
Aircraft
MAULE M-4-220C
Registration
N2007U
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Cruise

Probable cause

The pilot's improper decision to continue flight into an area of reduced visibility and snow showers during cruise flight, which resulted in the pilot's spatial disorientation and subsequent loss of aircraft control.

NTSB narrative

The private pilot departed for a short local flight while visual meteorological conditions existed in the immediate vicinity of the departure airport. He proceeded to climb to the northeast, through a mountain pass, and then to the south, paralleling the shore of a frozen, snow-covered reservoir. The flight continued for about 20 miles. Analysis of radar and recorded GPS data showed that the airplane then experienced large fluctuations in ground speed while still on the same approximate track. Shortly thereafter, the airplane began a 180-degree left turn and collided with the reservoir surface. GPS data, airplane instrumentation, and ground scars indicated that the airplane was in a descending left turn when it struck the ground. All major sections of airplane were accounted for at the accident site, and post accident examination of the engine and airframe revealed no obvious anomalies that would have precluded normal operation. Mountain obscuration and occasional precipitation were forecast for the area of the accident flight. Additionally, weather observation stations and local pilot reports indicated that moderate snow showers were in the vicinity of the site at the time of the accident. The white surface of the frozen lake, in conjunction with the snow and limited visibility, would have provided the pilot limited external visual references, and as such could have resulted in him becoming spatially disoriented or affected by a visual illusion. The pilot's logbooks revealed that he had a history of flying in marginal weather conditions, and had performed multiple Special VFR takeoffs and landings. The pilot did not possess an instrument rating.

Analysis

Primary failure mode
Spatial disorientation
First missed decision gate
Pilot could have chosen to return to the airport instead of continuing flight.

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 18 docket documents
View NTSB final reportView NTSB docket

Docket documents18

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