NTSB Identification: IAD97LA009.
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Accident occurred Sunday, October 20, 1996 in LEBANON, OH
Probable Cause Approval Date: 01/30/1998
Aircraft: Cessna 172A, registration: N9890T
Injuries: 1 Fatal.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The purpose of flight (flt) was to demonstrate tow release failure of a glider from a tow plane & to land under tow. The flt instructor (CFI) in the glider said the standard procedure for the tow plane was to depart with 10 deg of flaps & to turn left after takeoff. He said the tow pilot took off with 20 deg of flaps & made a right turn, then entered a steep turn to the left. Also, he said that during the steep turn, slack developed in the tow rope. The CFI tried to disconnect the tow rope, but was unable. The student said the rope became 'taught pulling up on the tow plane's tail.' The student then actuated the release; this time the rope released. The tow plane continued the left turn, nosed down, & struck the ground. The glider was landed uneventfully. Neither the tow plane nor the glider was equipped with a radio. Exam of the wreckage revealed no preimpact failure of the tow plane's flt controls or engine; 30 feet of tow rope was found attached to the tow plane, which had failed under tension. Two witnesses reported that the tow plt's hands always shook. One witness said his hands were shaking 'excessively' on the day of the accident. During toxicology tests, an undetermined amount of metoprolol was detected in the tow plt's blood & urine. Metoprolol is a medication that is frequently approved by the FAA for use by pilots with high blood pressure; drugs like metoprolol may also be used to treat a tremor.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: improper aircraft handling by the tow pilot and/or the glider pilots, which allowed the tow plane and glider to get out of position with one another; and failure of the aircrews (in both aircraft) to ensure a timely release of the glider tow rope. Full narrative available
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