History of Flight
On 10 March 2005, at approximately 1700 UTC, a Robinson R44 Raven II helicopter, registration G-CDEY, was involved in an accident while landing at Langley Castle Hotel, Haydon Bridge, Northumberland. The pilot, aged 59 and holding a Private Pilot's Licence with about 130 hours total flying experience (50 hours on type), had taken off from Manchester's Barton Airfield earlier that day with two passengers. They flew to Carlisle racecourse, where they spent the afternoon. The intended destination was a hotel approximately 35 nm away for a meeting with business partners. At about 1400 hrs, one of the group at the hotel telephoned the pilot to describe the landing site and inform him that the landing point would be marked with a white sheet.
The group departed the racecourse at about 1710 hrs and flew for about 20 minutes to the hotel. Upon arrival, the pilot overflew the landing site before beginning his approach. The landing site, a grass area approximately 60 m by 50 m adjacent to the hotel, sloped downhill away from the hotel and was surrounded on three sides by tall trees.
The pilot completed his approach and brought the helicopter into a low hover, turning to face up the slope to land. The helicopter touched down, and the pilot stated that at that moment he lost control. The helicopter pitched forward, striking one of its main rotor blades on the ground, then turned through 180°, striking its tail into the ground. The helicopter came to rest upright with the engine still running, but a fire quickly developed around the cabin. All three occupants vacated the aircraft unassisted and, apart from some singed hair, were unhurt. The weather was described by the pilot as good, with a 10 kt surface wind, ample visibility, and a cloud base of 3,000 ft. Sunset was at 1804 hrs.
Analysis
The pilot had little flying experience and had owned the aircraft for about two weeks prior to the accident. He had received training to land on sloping ground during his initial training on the Robinson R22 and during his conversion training for the R44, though he stated this was well before the accident.
According to the pilot's description, while landing on the slope, he mistakenly believed, while lowering the collective, that the full weight of the helicopter was on its skids with the collective in mid-travel. This prompted him to lower the collective rapidly to its minimum pitch position. The helicopter did not have its full weight on the skids at that time, causing it to settle quickly in a marked tail-down attitude as the collective was fully lowered. The motion took the pilot by surprise, and he instinctively reacted by pushing the cyclic rapidly forward, but without raising the collective. This caused the helicopter to pitch forward and strike its main rotors on the ground ahead, resulting in the remaining impact sequence. It was noted that because the helicopter remained upright, the occupants were able to escape unimpeded despite the subsequent fire.
Some time after the accident, the pilot returned to the landing site in another R44 helicopter with a flying instructor and successfully landed. The instructor reported that the slope on the landing site varied, with much of it sloping 10° or more, though some small areas were nearly level. He also commented that when below the level of the surrounding trees, sight of the horizon was effectively lost.
Discussions with the instructor indicated that the landing site presented numerous problems. The tall trees limited the choice of approach direction and, surrounding the aircraft, would have reduced available light on the final approach in near-dusk conditions. The slope of the landing site varied but certainly included a large area where the slope was probably at or above the landing capabilities for many light helicopters such as the R44. This, combined with a loss of visual horizon when descending below tree top level, presented a challenging landing site for any pilot.
The pilot acknowledged these points and mentioned the added pressures of flying with passengers, especially business partners, to such a venue. While confident he could land, he felt it would not have reflected favorably on his flying abilities had he failed to do so.
The hotel manager stated that approximately 10 helicopters a year land at the unofficial landing site without apparent problems, but he conceded he had little knowledge of helicopter operations and was not in a position to provide guidance beyond pointing out the location and obvious hazards such as the trees. He was unaware that the degree of slope would present a problem, and no pilot had ever complained about it.
In investigating the accident, the sloping ground limits for the R44 for landing or shutting down could not be obtained; however, the flying school where the pilot was taught recommends a limit of 10° for landing on a slope. Neither US nor European airworthiness regulations require manufacturers to determine or publish sloping ground limits. The manufacturer does not publish such limits because they are affected by numerous variable factors, including wind, ground conditions, and pilot skill.
Conclusion
The private pilot had little flying experience and was attempting to land at a difficult landing site for which he had little information. It is possible that had he known the degree of sloping ground and been able to compare it against published sloping ground limits for his helicopter, he may not have attempted the landing. In the event, while attempting to land, he applied an inappropriate landing technique followed by an inappropriate recovery technique when the helicopter appeared to be tipping backwards. This led to the main rotors striking the ground, destroying the helicopter.