Cessna 150 accident near Yulee, Florida, June 18, 2021

The NTSB's narrative final · quoted from the NTSB record

The flight instructor and the student pilot proceeded to the usual training area over a river for an instructional flight. Radar data indicated that the airplane completed several 360° turns, at slow speed, about 800 to 1,000 ft above ground level (agl); the observed maneuvering was consistent with the performance of slow flight. The last radar return was about 300 ft south of the accident site, at 800 ft agl. Several witnesses at a nearby boat dock reported that the airplane descended into the river in a near-vertical, nose-down attitude. One witness stated that the airplane was circling and turning while descending; another reported that the airplane descended nose down in a “corkscrew” path. The witness observations were consistent with the airplane having entered an aerodynamic stall and subsequent spin. Two of the witnesses recalled that the engine was running until impact with the water. The airplane sank in about 17 ft of water. An examination of the wreckage after recovery from the river did not reveal evidence of a preexisting mechanical malfunction or failure that would have precluded normal operation. The flight school that operated the airplane reported that the minimum altitude for recovery during air work, including stalls and slow flight, was 1,500 ft agl. Another student, who flew with the same flight instructor earlier that day, reported that the flight instructor routinely conducted air work below the 1,500 ft minimum. It is likely that the flight instructor allowed the student to stall the airplane at low altitude and delayed remedial action; the airplane subsequently entered a spin from which the instructor was unable to recover before impact.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.