Amateur-built LANCAIR IV-P TURBINE N5M accident near Lakeside, California

Probable cause

The pilot’s failure to maintain airspeed while attempting a visual climb through a broken cloud layer, which resulted in a stall/spin.

NTSB analysis

The noninstrument-rated private pilot departed on a cross-country flight in the amateur-built, experimental, turbine-powered airplane. The weather observations indicated two layers of clouds with multiple base layers from 3,600 feet above ground level (agl) and a broken ceiling about 6,000 feet agl. After departure, the pilot told an air traffic controller that he was looking for a hole to get above the clouds. The airplane was likely flying between the two cloud layers as the pilot attempted to find a hole in order to climb above the upper cloud layer. Six minutes after departure, witnesses on the ground observed the airplane descending in a "flat spin." The recorded data from the airplane's onboard electronic flight information system showed that the pilot had climbed to about 6,858-feet pressure altitude (about 5,800 feet agl) while letting the airplane's airspeed decay from about 220 knots to about 76 knots, at which time the airplane entered a spin. The data showed that the airplane completed about seven 360-degree rotations in the spin before it impacted the ground. Further, the data indicated that the airplane's engine was operating normally, and after the first 360-degree rotation, the propeller rpm dropped from about 1,800 to 1,000, consistent with the pilot feathering the propeller. Postaccident examination of the airplane revealed damage consistent with the airplane impacting terrain in a flat spin, and the propeller blades were found in the feathered position. No evidence of any preimpact mechanical discrepancies were found with the airplane's airframe, engine, or propeller that would have prevented normal operation.

The medications metoprolol and tamsulosin were detected at unquantified levels in the pilot's muscle and liver. Neither of these medications was likely to have resulted in impairment. The pilot had reported use of tamsulosin to the Federal Aviation Administration (FAA) in May 2011. The use of metoprolol was not reported to the FAA, and it is unknown when the pilot began taking this medication or for what reason he was taking it.

Text from the NTSB. Open the NTSB docket for WPR13FA076 for the full record.