What happened
On May 16, 1974, at approximately 10:35 AM, two Bücker aircraft were conducting landing training as part of a private aerobatics course at the Porrentruy airfield. The pilot of a Bücker APM 131-1s (HB-UUK) had completed seven landings and was taxiing back to the runway for a new departure on Runway 07. While taxiing, the pilot of HB-UUK passed a Piper J3C, HB-OXD, which was holding in a waiting position. The pilot of HB-UUK focused on the Piper and believed the crew of that aircraft was not yet ready for departure, leading to an insufficient scan of the approach sector.
Simultaneously, the pilot of a Bücker Lerche R-180 (HB-URT) was on final approach to Runway 07. As the pilot of HB-UUK applied full power to begin the takeoff roll, the aircraft entered the path of the arriving HB-URT. The pilot of HB-URT noticed the departing aircraft approximately two meters ahead and to the left just after touchdown, but an attempt to maneuver right was unsuccessful. The rudder of HB-UUK struck the lower left wing of HB-URT, and the propeller of HB-URT subsequently destroyed the rear fuselage of HB-UUK. Both aircraft spun right before coming to a stop roughly 32 meters apart. The collision resulted in one fatality and significant damage to both airframes.
The investigation
The investigation established that both pilots held valid licenses and had clean safety records for the preceding five years. Both aircraft were found to be airworthy and properly registered. Weather conditions at the time were clear with no clouds and a light northeast wind of approximately 2 knots. The investigation noted that no runway official using signal flags or lights was present to manage the airfield traffic at the time of the accident.
Findings
- The pilot of HB-UUK focused excessively on the stationary Piper HB-OXD during taxiing, which led to a failure to properly monitor the approach sector.
- Visual identification of the incoming HB-URT was made more difficult because the aircraft was positioned against rising terrain with varying colors.
- The pilot of HB-UUK failed to sufficiently scan the approach sector before entering the uncontrolled runway.
Safety action
- The investigation suggested that it would have been appropriate to appoint one of the other students present at the airfield to act as a runway controller using flags or light signals to regulate flight operations.