What happened
On 21 April 2012, a Vans RV-8, registration G-HILZ, was conducting a private flight from Duxford Airfield to a private airstrip located near Stevenage, Hertfordshire. The weather was generally calm, though a recent rain shower had left the grass runway surface wet.
During the landing phase, the pilot approached the 525 m strip from a south-westerly direction. While the approach speed and touchdown point were within intended parameters, the pilot encountered a significant lack of braking effectiveness. Despite applying the wheel brakes and attempting to use aerodynamic braking, the aircraft failed to decelerate sufficiently. As the aircraft overran the end of the grass strip, the pilot attempted to steer the plane away from a small hangar located at the end of the runway. While the maneuver altered the aircraft's heading by approximately 80 degrees, the ground track remained largely unchanged. The aircraft subsequently struck the side of the hangar, causing damage to the left wingtip, left tailplane, fuselage, and left landing gear, as well as minor damage to the hangar itself. There were no injuries to the pilot.
The investigation
The investigation examined the aircraft's performance capabilities and the environmental conditions at the time of the accident. The aircraft's performance data suggested a predicted landing roll of 300 to 500 feet under favorable conditions. Even when applying a safety factor of 1.431, the predicted roll was 1,030 feet; however, the actual distance traveled before impacting the building was approximately 1,350 feet.
Investigators looked into the surface conditions of the airstrip, noting that the recent rainfall followed a prolonged dry period. The pilot noted that the underlying sub-soil consisted of clay, which may have influenced the surface's behavior.
Findings
- The primary cause of the overrun was the unexpectedly poor braking effect experienced on the wet grass surface.
- The recent rain following a dry spell, combined with the specific clay-based sub-soil of the airfield, likely contributed to the lack of deceleration.
- The pilot's attempt to steer the aircraft away from the hangar was only partially successful in preventing the collision.