What happened
On June 16, 1974, a Cessna 182 A, registration HB-CPN, was performing a commercial sightseeing flight from the Sitterdorf airfield. The aircraft was carrying a pilot and four passengers, including two children. During the takeoff roll on the grass runway, the pilot attempted to lift the aircraft after traveling approximately 350 to 400 meters, but the plane failed to become airborne.
Recognizing the failure to rotate, the pilot initiated an aborted takeoff roughly 100 meters before the end of the runway. Despite the application of wheel brakes, the aircraft continued rolling past the runway boundary. Approximately 65 meters beyond the runway, the aircraft struck an embankment along a transverse road, which caused the nose gear to collapse and triggered a rollover. The aircraft came to rest on its back about 88 meters from the end of the runway. The pilot and one passenger sustained minor injuries, while the aircraft was destroyed.
The investigation
The investigation examined the aircraft's configuration, weight, and mechanical state. It was determined that the aircraft was operating near its maximum allowable takeoff weight. Investigators found that the aircraft was trimmed in a nose-heavy position, which, combined with the heavy load, would have required significant physical force on the elevator to achieve rotation.
Technical analysis of the wreckage revealed that the propeller pitch was not at its minimum setting, which reduced the engine's available power by approximately 12 percent. Additionally, the investigation looked into the flap settings, noting that while they were initially set to position 1, they were found retracted in the wreckage, suggesting they may have moved to the zero position during the roll. The fuel was found to be contaminated with water and traces of rust, though this was not considered a primary cause of the accident.
Findings
- The primary cause was the pilot's inability to lift the heavily loaded aircraft, leading to the aborted takeoff and subsequent excursion.
- Excessive propeller pitch prevented the engine from reaching full takeoff power.
- An improper flap configuration, or the possibility that flaps retracted to zero during the takeoff roll, contributed to the lack of lift.
- The aircraft was trimmed in a nose-heavy position, further complicating the rotation attempt.