On October 20, 1996, at 1327 eastern daylight time, N9890T, a Cessna 172A, performing a glider tow plane mission, registered to Lanes Lebanon Air Services, was destroyed when it collided with terrain after takeoff from the Lebanon Airport, Lebanon, Ohio. The certificated commercial pilot, the sole occupant, was fatally injured. Visual meteorological conditions prevailed and a flight plan was not filed. The flight was conducted under 14 CFR Part 91, and originated in Lebanon, at 1320. According to the Certified Flight Instructor (CFI) in the glider, the purpose of the flight was to demonstrate "Tow rope release failure and land under tow." In a written statement, the CFI stated that after liftoff of both the tow plane and glider, they headed to the northeast. In a telephone interview with the CFI, he stated that he had flown four prior flights successfully that day with other tow airplane pilots. He said he had flown with the tow pilot on other occasions and the standard departure was a left turn, but that day the tow pilot made a right turn, followed by a steep left turn. The CFI said that neither the tow airplane nor the glider was equipped with a radio; therefore, he told the student to follow the tow airplane. He said that the tow pilot took off with 20 degrees of flaps, rather than 10 degrees of flaps, which was not the normal procedure. He also stated that the tow airplane made steep turns at a low altitude. He also stated that prior to the flight, the tow rope had to be retied due to frays, and the pilot's had was shaking "excessively." The CFI said that he had seen the pilot's hand shake before, but that day it was more than usual. According to the student, the takeoff was normal. He said, "...Fly to the NE (unusual direction), begin 180 degree turn to the left (west) to set up for landing. During 1st 60 degree, or so, of this turn experienced sink and lift and slack tow rope. Recovered from slack rope. Finally, cont'd having addn'l slack rope & instructor took control of the aircraft. Slack rope became so bad that we could not see bottom of 'U' Instructor attempted to release without success. Tow plane continued left turn & seemed to be losing altitude...the instructor told me to pull the rope release, which I did & the rope did release. Several witnesses observed and heard the tow airplane before it entered a steep turn to the left and impacted the ground. One of the witnesses reported that he saw the Cessna 172 towing the glider. He said, "...the aircraft were not climbing but were turning left level back to the airport. I watched as the Cessna 172 nose dived, the glider came untethered at that time, but the Cessna 172 did not pull out of the nose dive. I watched as the Cessna 172 hit the ground... ." The tow airplane impacted terrain and nosed over. A glider tow pilot who had flown with the tow pilot on previous occasions, stated that she was in the process of checking out as a glider tow pilot. She stated that the tow pilot on previous flights used zero flaps, half standard turns and huge traffic patterns. She said that when she flew with the pilot, his hands shook and he appeared to be somewhat red-faced, or flushed in appearance. According to a Federal Aviation Administration (FAA) Safety Inspector, examination of the wreckage after the accident did not reveal any pre-impact failure of the airplane flight controls or engine. The FAA Inspector stated that a 30 foot section of the tow rope was the only tow rope found, and it was attached to the tow plane. He said that it had failed under tension. He also stated that the release mechanism on the glider was found in the open position. An autopsy of the pilot was performed by Dr. Rodney F. Tucay, Deputy Coroner, Montgomery County, Ohio, on October 21, 1996. Toxicological testing was conducted by the FAA Civil Aeromedical Institute (CAMI), in Oklahoma City, Oklahoma. The report stated that metoprolol was detected in blood and urine. According to the Physicians' Desk Reference, metoprolol is used for the treatment of hypertension and angina pectoris. Patients are advised "...to avoid operating automobiles and machinery or engaging in other tasks requiring alertness...The following adverse reactions have been reported...tiredness and dizziness...depression...mental confusion and short-term memory loss... ."