What happened
On 18 May 2006, a Beagle Wallis WA-116/F, registration G-ATTB, was conducting a private flight from Reymerston Hall to Robertson Barracks in Swanton Morley, Norfolk. Following a successful landing at a local playing field, the pilot took off into the wind to perform a final downwind pass for spectators.
During this maneuver, the aircraft was flying at cruising power when it encountered a sudden and significant loss of altitude. The pilot attempted to recover by turning left into the wind and applying full power; however, the aircraft continued to descend rapidly. The descent was so abrupt that the pilot described it as feeling "like a lift." The gyroplane eventually struck a set of small football goalposts on the playing field, resulting in a heavy landing.
The investigation
The AAIB examined the circumstances of the descent and the environmental conditions at the site. The investigation noted that the aircraft's flight path took it downwind of a wooded area. This woodland is characterized by a V-shaped configuration with a lake situated between 70-foot-high trees.
Investigators considered the impact of wind interaction with this terrain. The wind was predominantly from the south-west. The investigation established that the aircraft's position during the descent placed it directly within a zone where wind moving over the tree line could create turbulent air patterns.
Findings
- The aircraft sustained significant damage to the nose nacelle, rudder, fin, aft keel tube, propeller, and rotor, and the engine was shock-loaded.
- The pilot escaped the crash uninjured.
- The primary cause of the uncontrolled descent was a localized downdraught.
- It is believed that a strong gust of wind blowing over the adjacent woods likely created a rotor effect, resulting in a down-draught on the leeward side of the trees, which the aircraft encountered while flying downwind.