Amateur-built RV 6A N419B accident near Abilene, Texas

Probable cause

The pilot's failure to maintain airplane control during takeoff, which resulted in the airplane exceeding its critical angle of attack and an aerodynamic stall/spin. Contributing to the accident was the pilot's impairment due to his combined use of central nervous system depressant medications and the illicit drug marijuana, which degraded his ability to maintain control of the airplane.

NTSB analysis

The airline transport pilot and the passenger departed in the experimental amateur-built airplane that he had recently purchased on a cross country flight. After takeoff, the airplane drifted slightly right in a wings-level climbing attitude. A turn to the left with a bank angle of more than 30° began, and the airplane pitched nose-up followed by an immediate nose-down spin to the left. An onboard display unit recorded a left roll in excess of 80° and an indicated airspeed of 79 knots. Given that the airplane's estimated stall speed in level flight was about 49 knots and its estimated stall speed in a 75° bank is about 98 knots, it is likely the airplane entered an aerodynamic stall. An examination of the wreckage did not reveal evidence of any preimpact anomalies that would have prevented normal operation of the airplane. Damage to the propeller blades was consistent with engine power being delivered to the propeller, and witness marks indicated that the canopy was latched.

The investigation was unable to determine if the pilot's psychiatric conditions impaired his ability during the accident. There was no evidence that the pilot's cardiovascular disease was impairing. However, toxicology testing detected high levels of the medications buspirone and hydroxyzine and of tetrahydrocannabinol, the active compound in the illicit drug marijuana, in the pilot's blood. All three of these drugs are potentially-impairing, central nervous system (CNS) depressants, and, in combination, each drug may enhance the CNS depressant effects of the other drugs. Therefore, it is likely that the combination of the three drugs impaired the pilot's ability to safely fly the airplane.

Text from the NTSB. Open the NTSB docket for CEN16FA114 for the full record.