Accident Overview
On 16 May 1974 at 1035 hours MEZ, two Bücker aircraft collided on runway 07 at Porrentruy airfield. The aircraft involved were a Bücker APM 131-150, registration HB-UUK, and a Bücker Lerche R-180, registration HB-URT. Both aircraft were engaged in landing training as part of a private aerobatics course. The supervising flight instructor was positioned near the hangar, while two other course participants managed the takeoff and landing list from the southwest corner of the hangar.
Sequence of Events
After its seventh landing, the pilot of HB-UUK taxied back for another takeoff. A Piper J3C (HB-OXD) was holding at the runway 07 holding position. The HB-UUK pilot taxied past the right side of the Piper, believing its crew was not ready for departure. Upon aligning with the runway, the pilot reported having quickly checked the approach sector and seen no aircraft.
At the same time, the pilot of HB-URT was on final approach to runway 07. After lining up, the HB-UUK pilot applied full power. Shortly after touchdown, the HB-URT pilot noticed the departing Bücker approximately 2 meters ahead and slightly to the left; an evasive turn to the right was unsuccessful. The rudder of HB-UUK struck the left lower wing of HB-URT. Subsequently, the propeller of HB-URT shattered the rear fuselage of HB-UUK. Both aircraft then turned right, with HB-UUK following a tighter radius and HB-URT a wider one, coming to rest about 32 meters apart.
Findings
Both pilots held valid private pilot licenses. No relevant medical information was provided. Neither pilot had recorded any accidents or incidents in the previous five years. Both aircraft were airworthy and properly registered. Weather at the field was clear with a light northeasterly wind (approximately 2 knots). No runway marshaller with signal lights or flags was employed.
Probable Cause
The accident is attributable to the pilot of HB-UUK not sufficiently checking the approach sector before taxiing onto the uncontrolled runway.