What happened
On the evening of October 20, 1963, a Beagle Auster D-5/180 (registration G-ASBV) was performing aerobatic maneuvers at the Ecuvillens airfield in Switzerland. The aircraft, which was equipped with retractable metal skis for demonstration purposes, was operated by Beagle Aircraft Ltd. of the United Kingdom.
Following a takeoff from runway 10, the pilot initiated a series of maneuvers at an altitude of approximately 100 meters. After performing a tight 180-degree turn and a low-level pass, the pilot executed a loop. During the recovery phase of the loop, the pilot attempted a 90-degree right-hand turn while in a dive. Before the maneuver could be completed, the aircraft struck the grassy terrain a few meters north of the runway. The impact caused the aircraft to skid approximately 50 meters across the airfield, where it came to a halt on the opposite side of the runway. The aircraft was completely destroyed, and both the pilot and the passenger sustained two serious injuries involving multiple fractures.
The investigation
The investigation examined the pilot's experience, the aircraft's technical condition, and the environmental circumstances. The pilot was highly experienced, with over 1,700 flight hours, and had recently completed test flights in the specific aircraft. The aircraft was found to be in a valid state of airworthiness, and its center of gravity was within prescribed limits. The investigation also reviewed the regulatory framework regarding aerobatic flight heights and the specific flight permit for this experimental category aircraft, which prohibited aerobatic maneuvers.
Findings
The investigation concluded that the accident was most likely caused by a pilot error in altitude estimation while performing aerobatics at a low altitude. Several contributing factors were identified:
- The uncertain lighting conditions during twilight, combined with light mist in the area, likely hindered the pilot's perception of height.
- The difference in elevation between the Ecuvillens airfield and the pilot's usual operating environments may have contributed to the miscalculation.
- The maneuvers were being performed at an altitude significantly lower than the standard 500-meter requirement for aerobatic flights.