What happened
On the night of 1 May 2007, an AS355F2 Twin Squirrel, registration G-BYPA, was conducting a private return flight from Liverpool to a landing site near Thornhaugh. The flight, which included the pilot and three passengers, departed Liverpool at approximately 2219 hrs following a delay caused by a football match.
As the helicopter approached its destination, it encountered an area of shallow fog and low cloud. In an attempt to maintain visual contact with the ground, the pilot descended to roughly 20 feet at 60 knots, potentially using a light from a nearby haulage yard for guidance. During this low-level maneuvering, the aircraft likely became disoriented and lost control, striking treetops before crashing in Bedford Purlieus Wood. The impact resulted in 4 fatalities.
The investigation
Investigators examined the wreckage and recovered a GPS unit, which revealed the aircraft had been flying at a low level over gently sloping ground toward the edge of a forested area. The track showed the helicopter performing a climbing left turn and sharp turns just before impact.
Technical analysis of the AS355F2 revealed that the engines and flight control systems were functional and showed no evidence of pre-impact failure. The main rotor blades were under power at the time of the collision. While the radar altimeter was damaged, the setting was found to be at 120 feet. Witnesses at a nearby yard reported seeing the helicopter flying slowly at approximately 100 feet and hearing a sound similar to crashing metal shortly after the aircraft disappeared from view.
Findings
- The aircraft encountered low-level weather conditions, including fog and low cloud, which likely contributed to the pilot's decision to descend to a very low altitude.
- Spatial disorientation during the low-level flight likely led to the loss of control.
- The pilot's attempt to use ground lights for navigation while flying at 20 feet increased the risk of terrain impact.