What happened
On 21 August 2001, a De Havilland DHC-1 Chipmunk 22A, registration G-ARMC, was performing a private flight when it encountered difficulties during the landing phase at Westbury-sub-Mendip Airfield. The aircraft was executing a standard approach to Runway 29, which at the time featured a dry grass surface and light winds from 200 degrees at 5 knots.
As the aircraft touched down, the pilot encountered a specific terrain challenge: the runway featured an uphill gradient that leveled off into a crest, obscuring the view of the runway ahead. As the tail wheel made contact with the ground, the pilot's forward visibility was significantly reduced. Because the runway lacked visible markings, the aircraft began to drift toward the right side of the strip. After traveling roughly 100 metres, the right wing tip made contact with a nearby hedge. This impact caused the aircraft to spin toward the right, eventually colliding with the hedge again as the aircraft moved backward.
The investigation
The investigation, prompted by the accident report submitted by the pilot, examined the runway conditions and the sequence of the landing. Investigators noted the narrow nature of the runway and the presence of hedges on both sides of the strip. The assessment focused on the loss of visual references caused by the aircraft's attitude and the terrain profile during the rollout.
Findings
- The landing occurred on a dry grass surface with a slight rightward curve in the runway path.
- The aircraft sustained damage to its tail, tail wheel, and flaps.
- There were no injuries to the pilot or the single passenger on board.
- The primary factor in the excursion was the loss of visual references due to the aircraft's position and the runway's crest, which led to the aircraft drifting off the paved/cleared area and into the vegetation.