What happened
On 17 July 2001, a BN2A MK.III-2 Trislander, registration G-BDTO, was performing a scheduled public transport flight from Guernsey to Alderney. The flight involved 11 passengers and one pilot. As the aircraft approached Alderney Airfield, the pilot encountered deteriorating weather, including heavy rain and significant turbulence.
Upon touchdown on Runway 08, the aircraft failed to decelerate as expected. Despite the application of maximum braking, the aircraft continued along the runway, passing the intersection with a grass runway, and eventually exited the asphalt surface. The aircraft crossed a light fence and a track before coming to a halt in a nearby field. During the excursion, a tyre burst. There were no fatalities and no injuries to the crew or passengers.
The investigation
The investigation examined the aircraft's mechanical condition, the meteorological data, and the pilot's landing technique. Engineers inspected the braking system and found no mechanical anomalies, noting that the brakes functioned normally during tests on dry pavement. The investigation also looked into the emergency exit, finding that an excessive application of silicone sealant had effectively glued the Perspex panel into its frame, making it difficult to open during the evacuation.
Radar data revealed that the aircraft's ground speed at the threshold was significantly higher than normal for similar approaches. While the runway was wet and contained standing water, investigators found no classic physical evidence of aquaplaning, such as specific tyre marks or rubber reversion.
Findings
- The aircraft approached the runway with a higher than normal ground speed due to a significant tailwind component.
- The pilot utilized an inappropriate braking technique by maintaining the control column fully forward to assist with directional stability in the crosswind, which reduced the effective weight on the main wheels and decreased braking efficiency.
- The pilot was not informed by air traffic control that the runway surface was wet or contained water patches.
- The emergency exit was difficult to operate because the lower edge of the window was stuck in an excessive amount of sealant.