SPORTAVIA PUTZER RF5B SPERBER near Lookout Pass, MT — 2018-05-22

Probable cause

The pilot’s improper decision to continue flight toward rising terrain after the engine overheated, which necessitated a precautionary landing when the motorglider could not maintain altitude in downdrafts.

NTSB narrative

The airline transport pilot reported that, during a cross-country flight and while climbing toward a mountain pass, the experimental, amateur-built motorglider's engine began to overheat. The pilot delayed the climb to allow the engine to cool down and continued toward the pass, which resulted in reduced terrain clearance. As the motorglider approached the pass, it encountered a downdraft, and the engine was unable to produce enough power to stop the descent. Due to the reduced altitude, the pilot realized that he would be unable to safely turn the glider around, so he executed a precautionary landing on a freeway. During the landing, the glider struck a freeway barrier. The pilot reported that, other than the engine overheating, there was no evidence of any preimpact mechanical anomalies with the glider that would have precluded normal operation.

Analysis

Primary failure mode

Loss of control

First missed decision gate

Pilot could have chosen to land earlier instead of continuing towards Lookout Pass.

NTSB coding

• Loss of lift · Enroute-climb to cruise
• Decision Making / Judgment

Evidence available

• Video
• Photos
• 4 docket documents

Docket documents4

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Pilot's Statementinterview
• Photosphotos
• Video of Accidentvideo

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