What happened
On June 18, 1980, a Beechcraft Sierra (registration N6723 N) was conducting a flight training mission from Zurich to Courtelary. Following a brief stop, the flight instructor decided to continue the flight to the Môtiers aerodrome. Because the airfield office in Courtelary was closed, the crew did not provide the required prior notification for landing at Môtiers.
Upon arriving at Môtiers, the pilot landed on a wet grass runway. During the landing roll, the aircraft encountered a large puddle on the left side of the runway, causing the nose wheel to sink into the soft ground. The aircraft became immobilized and required assistance from three local pilots to be moved to a parking area. During the subsequent stay, the crew observed another aircraft successfully take off only after three attempts on the same wet surface.
For the departure from Môtiers, the flight instructor took control of the aircraft, while the student pilot was instructed only to manage the flaps. To avoid the muddy section encountered during landing, the instructor utilized the right side of the runway. After applying full power, the instructor initiated the takeoff rotation. However, the aircraft failed to maintain altitude and dropped back onto the runway. The instructor attempted a second rotation, but the aircraft lacked sufficient speed and runway length to continue. Despite heavy braking, the N6723 N struck an embankment at the end of the runway, crossed a stream, and came to rest in a meadow. The accident resulted in two serious injuries and the total destruction of the aircraft.
The investigation
The investigation established that the aircraft was in a valid condition with a valid certificate of airworthiness. The weight and center of gravity were within permissible limits. The investigation focused on the environmental conditions of the airfield, noting that the grass was wet and approximately 10 cm high, with a specific muddy area present on the runway. The investigation also reviewed the crew's decision-making regarding the lack of radio communication at Môtiers and the failure to notify the airfield of their arrival.
Findings
- The primary cause of the accident was inadequate takeoff technique.
- The takeoff attempt was aborted too late, leaving insufficient distance to avoid obstacles.
- The wet grass runway conditions contributed to the difficulty of the maneuver.
- The pilot's assessment of the runway conditions was overly optimistic.