What happened
On April 22, 1979, a Piper PA 23-250 (registration HB-LBG) was conducting a commercial pleasure flight from Ascona. The aircraft, carrying a pilot and six passengers, approached runway 35 under calm wind conditions. The pilot performed the approach with full flaps at an indicated airspeed between 80 and 90 mph.
Upon landing shortly after the runway threshold, the pilot attempted to use the brakes. However, the pilot reported that the braking effectiveness was only mediocre once the aircraft reached the midpoint of the runway. Fearing that attempting a go-around would be too risky given the remaining runway length, the pilot allowed the aircraft to continue rolling. The aircraft eventually overran the end of the runway by approximately 70 meters, where it collided with an earthen embankment created for nearby road construction works. While the aircraft sustained heavy damage to the nose, propeller, and landing gear, all seven occupants remained uninjured.
The investigation
Investigators examined the mechanical state of the braking system and the pilot's flight parameters. The aircraft's weight was approximately 2020 kg, well within its maximum allowable landing weight. Technical inspections of the braking system following the accident revealed no external hydraulic leaks, and the brake pads and discs showed normal wear. During testing, investigators found that while initial pedal depression was limited, pressure could be established by "pumping" the brakes.
Findings
- The approach speed was likely lower than the recommended 95 to 100 mph, potentially due to the pilot's attempt to minimize the landing roll.
- There may have been a slight tailwind that went unnoticed by the pilot.
- The primary cause of the accident was the inability to stop the aircraft in time after landing.
- Contributing factors included the possibility of dust, rust, or debris on the brake components, as well as the natural adaptation of worn brake linings to the discs.
- It was noted that the pilot's rest periods prior to the flight did not comply with established regulatory requirements.