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On February 6, 2001, approximately 1745 central standard time, two single-engine, high-wing airplanes, a Cessna 152, N114SS, and a Cessna 172P, N96621, collided in-flight near Platter, Oklahoma. The Cessna 152 was destroyed when it impacted Lake Texoma. The Cessna 172 sustained substantial damage during the collision, and the pilot then executed a precautionary landing at the Sherman Municipal Airport, Sherman, Texas, without further incident. The Cessna 152 was registered to and operated by Southeastern Oklahoma State University, Durant, Oklahoma, and the Cessna 172 was registered to and operated by Summerlin Aviation Inc., Keller, Texas, doing business as Monarch Aviation Inc., of Addison, Texas. The flight instructor and student pilot in the Cessna 152 sustained fatal injuries. The private pilot of the Cessna 172 and his non-pilot rated passenger were not injured. Visual meteorological conditions prevailed, and flight plans were not filed for either flight, both of which were operating under 14 Code of Federal Regulations Part 91. The Cessna 152 originated from the Eaker Field Airport, Durant, Oklahoma, approximately 1730, and was operating as a local instructional flight. According to the University, the purpose of the flight was for the flight instructor to provide the student pilot instruction that consisted of pre-solo flight maneuvers. The Cessna 172 originated from the Addison Airport, Addison, Texas, at 1707, and was operating as a personal flight.
According to the pilot of the Cessna 172, he departed from the Addison Airport to the north. He flew toward Lake Texoma and crossed over the Lake Texoma Spillway. He continued across the lake until approaching Oklahoma landfall and then turned the airplane toward the southeast. He maneuvered the airplane inbound to the Bonham Very High Frequency Omnidirectional Range (VOR) navigational facility, on a heading of 120 or 130 degrees. He stated that the visibility was clear with haze in the direction of the sun, which was setting. The airplane was in cruise flight at 3,500 feet and had just crossed the eastern shoreline of the lake when the pilot felt a "lump or thud," near the rear of the airplane. The pilot then felt air coming into the cabin from the left door and realized that the airplane required excessive right rudder to maintain directional control. He dialed 7700 (emergency code) into the airplane's transponder, declared "Mayday" on 121.5 and 122.8, and proceeded to the Sherman Municipal Airport, landing without further incident. The pilot added that he did not see the other airplane prior to, during, or following the collision.
Multiple witnesses reported that between 1740 and 1750 they heard a "pop" or "bang" and looked to the sky. They observed an airplane "spiral" toward Lake Texoma and subsequently, impact the lake 50 yards offshore from the Platter Flats area (located along the eastern shoreline of the lake). One witness reported that he observed a "break in one of the wings" of the plane which impacted the lake. The witnesses also observed another airplane near the spiraling airplane; however; it maintained flight and flew out of their view. Two additional witnesses observed two airplanes, near the time of the accident, over Lake Texoma, that were maneuvering at altitudes just above the tree tops. The airplanes were executing "loops" and performing "wing rolls." Although neither of these witnesses observed the mid-air collision, one of the witnesses stated that these airplanes were not the airplanes that were involved in the mid-air collision.
Radar data was obtained and reviewed. The Cessna 172 was tracked from the time of its departure from Addison to Platter. The radar data revealed that the Cessna 172 was in a descent just prior to the time the last radar image was received at 1741:21. The last radar image indicated that the Cessna 172 was at 2,900 feet over Lake Texoma. Radar coverage is not available in that area below 2,800 feet. At 1754:40, a series of primary radar targets were observed proceeding from the direction of the accident site toward the Sherman Municipal Airport. The radar data revealed that the target arrived at Sherman approximately 1800. There were no radar images or primary radar targets that could be identified as being the Cessna 152.
The certified flight instructor of the Cessna 152 was issued a flight instructor certificate on December 12, 2000. He also held a commercial pilot certificate (single-engine land) and an instrument (airplane) rating. According to documents provided by Southeastern Oklahoma State University, he had accumulated a minimum of 292 flight hours, of which 92 were while providing flight instruction. He held a first class medical certificate, with no limitations or waivers, that was issued on August 31, 1999.
The student pilot in the Cessna 152 enrolled in the private pilot course at Southeastern Oklahoma State University on August 18, 2000. He received 2.9 hours of instruction and then withdrew from the course. On January 20, 2001, he re-enrolled in the course. At the time of the accident, he had received a total of 11.7 flight hours of flight instruction. He held a first class medical/student pilot certificate that was issued on April 21, 2000. The medical certificate contained a limitation which stated the pilot must wear corrective lenses for distant vision and possess glasses for near vision.
The private pilot of the Cessna 172 was issued his single-engine land airplane rating on June 3, 2000. He had accumulated a total of 106 flight hours at the time of the accident. He held a third class medical certificate, with no limitations or waivers, that was issued on April 15, 1999.
The Cessna 172 was white with blue and gray trim. It was outfitted with a one piece wind screen and two sun visors. The airplane was equipped with a Lycoming O-320-D2J engine and a 2-bladed McCauley fixed pitch propeller. On February 2, 2001, the airframe and engine underwent their most recent 50-hour inspections. At the time of the accident, the airframe had accumulated a total of 11,331.6 hours, and the engine had accumulated a total of 833.8 hours since major overhaul.
The Cessna 152 was white with blue and gold trim. It was outfitted with a one piece wind screen and two sun visors. The airplane was equipped with a Lycoming O-235-N2C engine and a 2-bladed fixed pitch propeller. On January 15, 2001, the airframe and engine underwent their most recent 100-hour inspections and had accumulated a total of 9,463.1 hours and 396.3 hours since major overhaul, respectively. According to the airframe's 100-hour inspection sign-off form, the airplane's windows were examined and found to be in satisfactory condition, and the landing, cabin, and instrument lights were checked and found to be operational. The airplane's discrepancy log sheet was reviewed, and the following discrepancy was noted on January 31, 2001: Left wing-tip strobe light out. The log sheet did not note that any corrective action had been performed.
At 1755, the weather observation facility at the Ardmore Downtown Executive Airport, Ardmore, Oklahoma, (located 30 nautical miles northwest of the accident site) reported the following conditions: clear skies, visibility 10 miles, wind from 060 degrees at 3 knots, temperature 16 degrees Celsius (60 degrees Fahrenheit), dew point 10 degrees Celsius (50 degrees Fahrenheit), and an altimeter setting of 29.96 inches of mercury.
According to the U.S. Naval Observatory, sunset for Calera, Oklahoma, (located 7 nautical miles east of the accident site) occurred at 1802 and the end of civil twilight occurred at 1828.
WRECKAGE AND IMPACT INFORMATION
The Cessna 172 was examined at the Sherman Municipal Airport by the NTSB Investigator-In-Charge (IIC), an FAA inspector, and a representative from Cessna Aircraft Company. The pilot's door was compressed inward 5 inches, exhibited impact damage, and could not be opened. The airplane displayed longitudinal red and blue paint transfer markings, which initiated at the left wing strut and extended aft along the exterior lower half of the pilot's door. The witness marks continued aft along the left side of the fuselage and empennage ending approximately 1 foot forward of the horizontal stabilizer. One dent was noted at the midpoint of the left horizontal stabilizer's leading edge. A vertical slash was observed on the bottom side of the empennage, which initiated at a point 3 feet forward of the tail tie down ring and extended aft 2 feet. Two puncture holes were noted on the upper right side of the empennage, which corresponded to a propeller blade tip exiting the airframe skin. The puncture holes were located approximately 3 feet 10 inches aft of the rear windscreen. Additionally, a severed rudder cable was observed in the empennage, near the area of the slash. The pilot's door was then removed from the airframe. A shattered red lens, shattered clear lens, sections of a wing-tip cap, and coil from a strobe light were observed on the cabin floor. The windscreen was observed to be clean and free of scratches. The airplane's beacon light, landing light, and wing-tip strobe lights were checked. They were found to be operational.
A debris field was located near the Platter Flats area, which extended inland approximately 150 yards. The debris field included sections of the Cessna 152's left wing-tip cap, a 4-foot section of its left aileron control surface, and its left strobe light power box attached to a 2-foot section of wing skin. The Cessna 152 was recovered from the lake and transported to a nearby storage facility.
The Cessna 152 was examined by the NTSB IIC and a representative from Cessna Aircraft Company. Both wing leading edges were compressed rearward to the flaps and ailerons. A 4-foot, 4-inch section of the left aileron (from its most outboard point extending inboard), wing-tip cap, left wing red lens navigation light, left wing clear lens strobe light, and the strobe box along with sections of the left wing's skin were missing. Blue paint transfer marks were observed on the outboard section of the left wing's leading edge. Both wing struts remained attached to the wing attach points; however, they separated from their respective fuselage attach points. The vertical stabilizer, rudder, horizontal stabilizer and elevator remained intact; however, they were structurally damaged. The cockpit was destroyed during the impact. Flight control continuity was established for the aileron, elevator, elevator trim and rudder control systems. The flaps were determined to be in the retracted position.
MEDICAL AND PATHOLOGICAL INFORMATION
Autopsies were performed on the flight instructor and student pilot of the Cessna 152 by the Office of the Chief Medical Examiner of Oklahoma City, Oklahoma. The cause of death for both pilots was determined to be multiple injuries due to an airplane accident. Toxicological tests were performed on both individuals by the FAA's Civil Aeromedical Institute of Oklahoma City, Oklahoma, and were negative for carbon monoxide, cyanide, ethanol, and drugs.
During the investigation, it was learned that the flight program at the Southeastern Oklahoma State University had been continually expanding since its inception. At the time of the accident, the University operated a fleet of 15 airplanes, of which 10 were Cessna 150 and 152 models, from the Eaker Field Airport. The Airport/Facility Directory was reviewed and no remarks were found indicating that extensive flight training was occurring near the airport and over Lake Texoma. As a result of the investigation, the following statement was added to the remarks section of the Airport/Facility Directory for the Eaker Field Airport: Extensive student training in the vicinity of the airport and Lake Texoma.
The Cessna 172 was released to its owner's representative on February 22, 2001, and the Cessna 152 was released to its owner's representative on February 23, 2001.