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NTSB investigation record

WPR12CA213

Completed

Rotherwick HR Glasair III· N471B

Date
May 17, 2012
Location
Darby, MT
Conditions
VMC
Record
Published September 25, 2020

Primary finding

Probable cause

The pilot’s loss of directional control during an emergency landing on a paved highway.

Investigator assessment

Analysis narrative

The pilot reported that, about 2 hours into a visual flight rules cross-country flight, he enriched the mixture due to indications of excessive cylinder head and exhaust gas temperatures. This resulted in a higher fuel burn than planned, so he changed the flight’s destination 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-degree 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 from flying out of the valley. Now very close to fuel exhaustion, he elected to land on a two-lane highway. During the landing roll, the airplane veered off the side of the road, impacted a tree, slid backwards through a ditch, and collided with a concrete drainage culvert. The airplane sustained damage to the outboard sections of both wings.

Source record

Factual narrative

***This report was modified on August 7, 2012. Please see the dcoket for this accident to view the original report.*** The pilot reported that, about 2 hours into a visual flight rules cross-country flight, he enriched the mixture due to indications of excessive cylinder head and exhaust gas temperatures. This resulted in a higher fuel burn than planned, so he changed the flight’s destination 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-degree 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 from flying out of the valley. Now very close to fuel exhaustion, he elected to land on a two-lane highway. During the landing roll, the airplane veered off the side of the road, impacted a tree, slid backwards through a ditch, and collided with a concrete drainage culvert. The airplane sustained damage to the outboard sections of both wings.

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