Tl Ultralight Sro STINGSPORT N797N accident near Madera, California

Probable cause

The pilot's exceedance of the airplane's critical angle of attack during the simulated engine failure on initial climb after takeoff, which resulted in an aerodynamic stall and subsequent loss of control at too low of an altitude to recover.

NTSB analysis

The flight instructor and the student pilot were conducting traffic pattern work, landings, and takeoffs. A pilot who was flying in the area reported hearing one of the accident airplane’s pilots announce that they would perform an "emergency turn around at 500 ft." Two witnesses listening to communications at the airport reported that the last communication they heard from the accident airplane was that the pilot would be executing a simulated emergency landing to the runway. Data obtained from a GPS unit on board the accident airplane showed that about 1 minute after departure, at a GPS altitude of 764 ft above ground level and a groundspeed of 64 knots, the airplane began a 180° descending right turn back toward the airport. The final recorded data point was 16 seconds later, with a reported GPS altitude of 324 ft and a groundspeed of 21 knots. The airplane impacted terrain in a nose-down attitude about .5 nautical miles from the departure end of the runway. It could not be determined which pilot was manipulating the flight controls when the accident occurred.

Postaccident examination of the airframe and the engine did not reveal any evidence of preexisting mechanical malfunctions that would have precluded normal operation.

Toxicology testing of specimens from the flight instructor detected metoprolol, rosuvastatin, and glipizide, which were not impairing and, thus, would not have contributed to the accident. Toxicology testing of specimens from the student pilot detected tetrahydrocannabinol (THC), the active compound in marijuana. Although the concentration of THC found in cardiac blood suggests that marijuana usage may have occurred earlier that day, blood concentrations do not correlate well with impairment and cannot be used to prove that the user was under the influence of the drug at the time of testing. Thus, it is unlikely that the student pilot’s use of marijuana contributed to the accident.

Based on the available evidence, it is likely that during the simulated engine failure on initial climb after takeoff, the pilot inadvertently exceeded the airplane’s critical angle of attack, likely by allowing the airspeed to decay, and the airplane experienced an aerodynamic stall at an altitude too low for recovery.

Text from the NTSB. Open the NTSB docket for WPR19FA121 for the full record.