YAKOVLEV YAK 52 — Syracuse, KS

What happened

The private pilot/owner was conducting a local personal flight. GPS data from a handheld device recovered from the airplane revealed that, after takeoff, the pilot maneuvered in the vicinity of the airport. About 22 minutes after takeoff, the pilot twice overflew a residence located about 0.25 mile northeast of the accident site; both overflights were made from east to west, and the pilot flew a left racetrack pattern between the overflights. Immediately after the second overflight, the pilot entered a left turn. A witness observed the airplane turning left when its nose dropped, and it "fell straight down." The final GPS data point was recorded after the airplane had completed about 90 degrees of heading change to the south and was about 500 ft above ground level. The accident site was located about 400 ft east of the final data point, indicating the airplane completed about a further 90 degrees of heading change before ground impact.

Examination of the accident site indicated that the airplane impacted an open field in a nose down attitude and came to rest upright. A postaccident examination of the airframe and engine did not reveal any anomalies consistent with a preimpact failure or malfunction.

The GPS data indicated that the pilot maneuvered extensively during the flight; however, it did not indicate that he was performing aerobatic maneuvers at any point. The data suggest that the final left turn was flown with a gradually decreasing turn radius consistent with an increasing angle of bank. The abrupt departure from controlled flight as depicted in the GPS data and described by the witness is consistent with the wing's angle-of-attack exceeding its critical angle-of-attack during the turn, resulting in an aerodynamic stall. The stall occurred at an altitude that was too low for recovery.

A review of medical and pathological information related to the pilot indicated that a sudden incapacitation or significant cardiac event precipitating the accident was unlikely. Diphenhydramine, a sedating antihistamine, was detected in the pilot's blood. However, the level of the medication in the pilot's system at the time of the accident could not be accurately determined from the available toxicological data. Therefore, the extent of any impairment due to diphenhydramine at the time of the accident could not be determined.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.