Aircraft: Glasair III. Injuries: None. Location: Darby, Mont. Aircraft damage: Substantial.
What reportedly happened: According to the pilot, approximately two hours into a VFR cross-country flight, he noted indications of excessive cylinder head and exhaust gas temperatures.
He attempted to correct the issue by enrichening the mixture, which resulted in a higher fuel burn than he had planned, so he diverted to a closer airport.
While en route to his amended destination, he encountered instrument meteorological conditions. A subsequent buildup of ice resulted in a loss of 100 knots of airspeed as the airplane entered a controlled descent.
The pilot executed a 180° turn and broke out of the clouds over a valley. During the next 50 minutes, he made several attempts to exit the valley, however, mountain peak obscuration and a thunderstorm prevented him doing so.
With the airplane very close to fuel exhaustion, he elected to land on a two-lane highway. During the landing roll the airplane went off the side of the road, into a tree and came to rest in a concrete drainage culvert.
Probable cause: The pilot’s loss of directional control during an emergency landing on a paved highway.
NTSB Identification: WPR12CA213
This May 2012 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.