NTSB Identification: CHI02FA025.
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Accident occurred Monday, November 12, 2001 in Dyer, IN
Probable Cause Approval Date: 12/30/2003
Aircraft: Cessna 150M, registration: N63262
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

During an instructional flight the airplane entered an inadvertent spin and subsequently impacted the terrain. The plotted aircraft radar track data showed the airplane performing a maneuver consistent with a clearing turn prior to the airplane decelerating at a constant altitude. The plotted data then shows the airplane reversing course and entering a spiraling descent. The average descent rate for the last 50.82 seconds of aircraft radar track data was 2,125 feet/minute. No anomalies were found with the accident airplane that could be associated with a pre-impact condition. Diphenhydramine (trade name Benadryl), an over-the-counter antihistamine with sedative effects, was detected in the blood of the certified flight instructor (CFI) at a level consistent with that found about 2-3 hours following ingestion of a single maximum over-the-counter dose. The effects of over-the-counter antihistamines, including diphenhydramine, was evaluated in a medical study, which concluded that a normal over-the-counter dose of diphenhydramine adversely affected performance more than a 0.1% blood alcohol concentration. The study further concluded that there was no correlation between drowsiness and impairment.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The failure of the flight crew to maintain adequate airspeed, resulting in an inadvertent stall/spin and the flight instructor's inadequate supervision of the flight, his impairment due to the use of over-the-counter medication is a contributing factor.

Full narrative available

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