N4116YBellanca 8GCBC · 1976

On May 9, 2020, about 1319 Pacific daylight time, a Bellanca 8GCBC, N4116Y, was destroyed when it was involved in an accident at Byron Airport (C83), Byron, California. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 glider tow flight.

The glider that was being towed by the accident airplane was a Schweizer SGS 1-26E. The pilot of the glider reported that the accident flight was his and the tow airplane pilot’s second flight of the day and that their first flight was uneventful; the airplane towed the glider to an altitude of 3,500 ft, at which point the tow pilot released the glider. For the second flight, the glider pilot stated that he performed the preflight checklist, which included verifying that the canopy was closed and locked. According to the glider pilot, after a normal takeoff, the tow airplane pilot initiated a slight right turn; shortly afterward, the canopy of the glider opened. The glider pilot further stated that the canopy began “flapping” open and closed and that he attempted to secure the canopy while controlling the glider. The glider pilot added that he became briefly disoriented but was able to turn back toward the airport, which is when he saw that the tow airplane had crashed at the end of the runway.

Airport security camera recordings as shown in the figure below, captured the accident sequence. The tow airplane became airborne about midway along the length of the runway and made a shallow climb with the glider in trail at a similar altitude. About 7 seconds after the tow airplane became airborne, the glider pitched upward and ascended to a higher altitude while the tow airplane remained in a shallow climb. Three seconds later, the tow airplane began a shallow descent. About 2 seconds later, the tow airplane and glider appeared to remain level at their respective altitudes, with the glider at a higher altitude than the tow airplane. About 4 seconds later, the tow airplane and glider appeared to descend. The glider then began to ascend about 4 seconds later, while the tow airplane pitched downward to a nose-low attitude. The tow airplane impacted the runway and nosed over, and a postimpact fire ensued. The glider executed a 180° right turn and landed uneventfully on runway 12.

Figure. Screenshots of the accident sequence from a security camera recording (Source: Byron Airport).

A pilot-rated witness who was near the airport reported that he saw the tow airplane during its departure. At that time, the tow airplane was about 50 ft above ground level (agl) with the glider in trail. The witness stated that the glider then “abruptly and abnormally climbed” about 25 ft above the tow airplane. The witness also stated that the glider initially maintained that position but then quickly descended about halfway down to the tow airplane’s altitude, which was about 125 to 150 ft agl. The witness further stated that, as the tow airplane and glider passed midway between the taxiway A1 turnoff and the end of runway 30, the tow airplane was at an altitude of about 100 ft agl. The tow airplane seemed to be attempting to maintain altitude, but the glider began to climb again. The witness thought that there was a “30-40° angle on the tow line.” The witness further stated that, about 500 ft from the departure end of the runway, “the glider…caused the tow line to pull up on the tail of the tow plane abruptly.” The witness added that the tow line had apparently been cut, but the tow airplane was in an “aggressive nose-low attitude” and impacted the ground in a 45° nose-low attitude.

Examination of the accident site revealed that the airplane’s fabric covering was mostly consumed by fire, but the primary structure of the wings, fuselage, and empennage were intact. All flight control cables remained attached to their respective flight controls. The rope cutting mechanism (guillotine) in the airplane was found in the engaged position.

Postaccident examination of the tow airplane revealed no preexisting mechanical malfunctions that would have precluded normal operation.

The canopy latch mechanism on the glider was actuated numerous times and functioned normally. The tow rope was located about 80 feet beyond the main wreckage of the tow airplane in the grassy area adjacent to the runway. Photos of the tow rope showed that one end appeared to be cut, while the opposing end, which included the tow rings, was intact.

The Federal Aviation Administration’s (FAA-H-8083-13A), chapter 12, pages 12-11 and 12-12, state in part the following regarding the action to be taken if a glider climbs excessively high during takeoff:

The tail of the tow plane may be lifted if the glider climbs excessively high during takeoff. Should this happen, the application of full-up elevator on the tow plane may not be sufficient to prevent an accident. The tow pilot must be ready to pull the release handle in order to regain control of the tow plane. As a rule of thumb, use of a 200-foot tow line would require the glider to climb to over 20 feet above the altitude of the tow plane to present a danger of upset.

If at any time the nose of the tow plane is pulled uncontrollably by the glider to a dangerously high or low pitch attitude— PULL THE RELEASE.

The Coroner’s Division of the Office of the Sheriff, Contra Costa County, California, performed the tow pilot’s autopsy. According to the autopsy report, his cause of death was multiple blunt impact injuries.

Toxicology testing performed at the Federal Aviation Administration Forensic Sciences Laboratory found glipizide and metoprolol in the pilot’s blood and liver specimens and pantoprazole in his blood specimens. Glipizide is a prescription medication that is commonly used to treat high blood sugar levels. Metoprolol is a prescription medication that is used to improve survival after a heart attack and treat high blood pressure, heart-related chest pain, and certain types of heart failure. Pantoprazole is a prescription medicine that is used to suppress stomach acid. Those medications are generally considered not to be impairing.