What happened
On the evening of 28 January 1998, a Eurocopter AS355N Ecureuil II, registration G-OROM, was involved in a fatal accident near Souldern, Oxfordshire. Following a successful night training session at Oxford Kidlington airfield, the pilot departed his private landing site for a short flight.
After an initial departure, the helicopter was observed by witnesses near the pilot's residence at a low altitude. Shortly thereafter, motorists on the M40 motorway witnessed the aircraft descending at a steep angle from a height of approximately 100 to 300 feet. The helicopter appeared to accelerate rapidly before impacting the ground in a field near Souldern Grounds Farm. The impact, which occurred at a high forward speed, caused the airframe to disintegrate and ignited the fuel supply, resulting in a significant post-impact fire. The pilot sustained fatal injuries.
The investigation
Investigators examined the wreckage and the engines, finding that both Turbomeca Arrius 1A engines were operating normally and at high speed at the moment of impact. The aircraft's systems, including the electrical, hydraulic, and fuel systems, were fully functional prior to the crash. No mechanical failures or flight control malfunctions were identified.
Analysis of the flight path via radar and witness testimony revealed that the pilot had deviated from a standard climbing profile. While the intended flight path involved a climb to 1,000 feet, the aircraft remained at a much lower altitude. The investigation also considered the impact of environmental factors, such as the presence of mist and the lack of external visual cues due to the darkness of the night.
Findings
- The pilot encountered a layer of mist which likely obscured the horizon and degraded visual references.
- The pilot may have experienced spatial disorientation caused by a combination of the moving light beam from the landing light and the lack of a stable horizon.
- The transition from climbing to level flight, alongside the loss of ground visibility, likely created a false sensation of the aircraft pitching upward, leading the pilot to apply forward cyclic control and inadvertently increase the rate of descent.
- The terrain warning system provided only a very brief warning before the high-speed impact occurred.