What happened
On August 24, 2009, a Piper PA-28-180 Cherokee, registration HB-OYN, departed from the Lommis grass airstrip for a private VFR flight. Shortly after the aircraft became airborne, the pilot increased the angle of attack, leading to an aerodynamic stall. An optical stall warning light had activated approximately eight seconds after takeoff. The aircraft subsequently lost altitude and entered a right-hand roll, impacting a cornfield approximately 670 meters beyond the end of the runway. The impact caused the landing gear to collapse and a fire to break out in the engine compartment, which destroyed the aircraft's forward fuselage. While the four occupants survived, the two passengers in the front seats sustained facial injuries when they struck the instrument panel.
The investigation
The investigation examined the aircraft's weight and balance, the meteorological conditions, and the pilot's experience. The aircraft was operating at a high takeoff mass during a period of high ambient temperatures, resulting in a density altitude of approximately 3,700 feet. Investigators also reviewed video footage captured by a passenger on a mobile phone, which documented the flight sequence and the passengers' vocalizations during the takeoff roll. The investigation confirmed that the aircraft was well-maintained and that the pilot, while possessing limited total flight time, held the necessary licenses. No mechanical failures or pilot impairment from substances were identified.
Findings
Several contributing factors were identified in the loss of control:
- The pilot continued to increase the pitch angle despite the activation of the stall warning.
- The pilot's limited flight experience contributed to the inability to manage the stall recovery.
- High takeoff weight combined with high outside temperatures increased the density altitude.
- A potential shift toward a tailwind component occurred as the aircraft climbed out of the surface wind layer.
- The pilot was distracted by loud, enthusiastic vocalizations from the passengers during the takeoff roll.
- The aircraft was only equipped with lap belts; the absence of shoulder harnesses contributed to the injuries sustained by the front passengers.
Safety action
Following the accident, a safety recommendation was issued to the Federal Office of Civil Aviation (FOCA) to facilitate the retrofitting of shoulder harnesses in older aircraft models, particularly where supplemental type certificates (STC) are available to improve occupant protection during impact.