What happened
On the afternoon of November 6, 1981, a Piper PA-28-161 Warrior, registration HB-PEV, touched down at Les Eplatures aerodrome in Switzerland after a short flight from Yverdon. The aircraft was carrying the pilot and three passengers. Following a brief stopover, the pilot decided to return immediately, citing weather concerns about potential cloud formation on the plateau.
At approximately 15:28 local time, HB-PEV departed runway 06. Shortly after liftoff, as the aircraft climbed to an altitude of roughly 50 to 80 meters, a witness reported hearing engine misfires followed by a complete loss of power. The pilot attempted to execute a left-hand turn to avoid obstacles in the departure path. However, the aircraft entered a stall during this maneuver and crashed into a field adjacent to an industrial facility at approximately 16:00.
The impact resulted in the total destruction of the airframe. The pilot and one passenger sustained fatal injuries, while the two remaining passengers suffered serious injuries. Fortunately, all occupants were wearing seatbelts, which withstood the force of the crash, and rapid intervention by local firefighters allowed for their extraction.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) conducted a thorough examination of the accident site, the aircraft wreckage, and the flight records. Investigators recovered the fuel selector switch in the position pointing to the right wing tank. Examination revealed this tank was nearly empty, containing only 0.3 deciliters of usable fuel. In contrast, the left wing tank, though damaged upon impact, still contained approximately 22 liters of gasoline.
Technical inspections of the engine, magneto systems, ignition leads, and carburetor showed no mechanical defects that could explain the power loss. The aircraft's weight and center of gravity were within prescribed limits. Medical examinations of the pilot confirmed he was fit for flight, with no evidence of medical impairment or alcohol consumption.
Fuel consumption calculations based on previous refueling logs and flight times indicated that the right tank should have been depleted by the time of the accident. The chief instructor who had flown the aircraft prior to the pilot's second departure noted that he had used fuel exclusively from the right tank. Despite this, the pilot failed to switch the selector to the left tank before takeoff, as required by the checklist.
Findings
The primary cause of the accident was loss of control after takeoff during an obstacle avoidance maneuver, resulting from a complete engine failure due to fuel starvation. A significant contributing factor was the pilot's failure to switch the fuel selector to the fuller left tank before departure, contrary to standard operating procedures.
The investigation determined that the engine stopped because it ran out of fuel in the selected right tank. The subsequent stall occurred because the aircraft was relatively heavy and climbing at a low altitude, leaving insufficient energy and height to recover from the power loss during the evasive turn.
Safety action
This accident highlights the critical importance of adhering to pre-takeoff checklists, particularly regarding fuel quantity verification and selector position. It underscores the necessity for pilots to actively manage fuel cross-feed or tank selection during multi-tank operations, especially when transitioning between flights with different flight profiles.