Amateur-built TIERRA II N622MC accident near Montevideo, Minnesota

Probable cause

The pilot's impaired judgment due to the use of marijuana, which led to his improper decision to fly the airplane over its maximum gross weight and his subsequent loss of airplane control during takeoff with gusting wind conditions.

NTSB analysis

The private pilot took off in his experimental, amateur-built airplane for a local flight in gusting wind conditions. A witness reported seeing the airplane climb to about 200 to 300 ft above ground level. The airplane leveled off, started to make a left turn, and its right wing then went "straight up." The witness reported that it was "almost like it was hit by a gust of wind" and that the airplane "did a 1/2 turn" and descended straight down into the ground. Wind recorded at the airport about the time of the accident was 10 knots gusting to 14 knots.

An airframe and powerplant mechanic reported that he had been conducting a condition inspection of the airplane before the accident and that it had not been completed. However, postaccident examination of the airplane's structure, engine, propeller, and controls revealed no evidence of preimpact malfunctions or failures. The calculated takeoff weight of the airplane and occupants, not including the fuel load, was at least 147 lbs greater than the airplane's placarded gross weight. It is likely that the combined effects of the airplane being over its maximum gross weight and the gusting wind conditions led to the pilot's failure to control the airplane after takeoff.

Toxicology testing identified tetrahydrocannabinol (THC), the psychoactive component of marijuana, and its metabolites in the pilot's peripheral blood. The detected levels of THC and its metabolites indicated that the pilot likely smoked marijuana in the few minutes to 2 hours before the accident, which impaired his decision-making and contributed to his decision to attempt to fly with the airplane significantly over it maximum gross weight in gusting wind conditions.

An autopsy also showed that the pilot's heart was enlarged; however, no other coronary artery disease was identified. Although the pilot's enlarged heart could have caused him symptoms such as shortness of breath or swelling, it would not have impaired his judgment.

Text from the NTSB. Open the NTSB docket for CEN14LA485 for the full record.