What happened
On June 2, 1968, a training flight involving a student pilot and an instructor transitioned from Wangen-Lachen to Birrfeld for landing practice. During the session, the student pilot performed several approaches to the grass runway. After an initial successful landing, subsequent approaches were characterized by excessive altitude and airspeed.
During one attempt, the student pilot encountered a ground wave that caused the Bölkow Junior HB-UPH to bounce approximately 10 meters into the air. In an effort to prevent a loss of airspeed during the resulting go-around, the pilot applied excessive forward pressure on the controls. This maneuver caused the nose to dip too low, resulting in the nose gear striking the ground and bending backward at an angle of approximately 30 degrees. Unaware of the structural damage, the student pilot continued the flight pattern.
On a subsequent landing attempt, the aircraft's nose gear collapsed completely upon touchdown. The impact caused the aircraft to roll onto its back in the center of the runway. The student pilot was able to exit the aircraft immediately with the assistance of the instructor.
The investigation
An investigation conducted by the Swiss Federal Aircraft Accident Investigation Commission examined the sequence of events and the pilot's actions. The inquiry reviewed the student pilot's training progress, noting they had previously completed solo landings at other airfields. The investigation also assessed the environmental conditions, noting the weather was clear and nearly windless, though heavy glider and motor glider traffic at Birrfeld may have contributed to pilot distraction.
Findings
- The student pilot's approach speeds were estimated between 75 and 80 knots, exceeding the ideal 70-knot glide speed.
- The primary cause of the accident was the excessive forward pressure applied to the controls during a go-around, which forced the nose gear into the ground.
- The student pilot's awareness of the initial damage was absent, allowing the flight to continue with a compromised landing gear.
- High levels of air traffic at the airfield may have increased the student's stress levels, contributing to the unstable approach speeds.