What happened
On January 2, 1978, a Morane Saulnier MS 894 A, registration HB-ERZ, attempted a commercial sightseeing flight from the Hasenstrick airfield. The pilot, carrying three passengers, began the takeoff roll on runway 11, which was covered in approximately 5 cm of fresh snow that had begun to thaw.
During the acceleration, the pilot noted a period where the aircraft felt light, but a sudden, jerky deceleration occurred midway down the runway. Despite this, the pilot continued the takeoff attempt. The aircraft failed to rotate before reaching the end of the runway. Due to the downward slope of the terrain beyond the runway, the aircraft transitioned into the air, but the pilot's attempt to gain speed led to the aircraft striking a treetop approximately 140 meters past the runway end. The impact caused a rapid loss of altitude, and the aircraft struck the ground with the crew and passengers on board.
The investigation
Investigators examined the runway conditions, the aircraft's maintenance history, and the pilot's techniques. The investigation established that the aircraft was in good mechanical condition with no evidence of engine power loss. The weight and balance were within limits.
Analysis of the tracks in the snow revealed that the aircraft did not lift off before the end of the runway. While the nose wheel was intermittently light, it continued to touch the ground, specifically striking the surface about 10 meters before the runway end. The investigation also reviewed the airfield's operating regulations and the specific takeoff procedures recommended by the manufacturer for short runways.
Findings
- The primary cause of the accident was the use of inappropriate takeoff technique under difficult surface conditions.
- The pilot did not fully implement the manufacturer's prescribed short-takeoff technique, which involves an abrupt pitch-up at a specific speed.
- There was insufficient instruction regarding the correct use of the aircraft's specific handling characteristics for short-field operations.
- The pilot failed to abort the takeoff when the sudden deceleration occurred at the halfway point of the runway.
- The airfield's internal rule, which suggests aborting a takeoff if rotation has not occurred by the halfway mark, was deemed ineffective because the specific distance is not clearly marked and does not account for degraded surface conditions.
Safety action
- The investigation noted that the lack of consistent application of the manufacturer's recommended short-takeoff technique was detrimental to safety on such a short runway.