What happened
On 13 March 2014, an Agusta AW1s39, registration G-LBAL, was scheduled to fly from Gillingham Hall to Coventry Airport. The departure was delayed from 1830 hrs until approximately 1920 hrs because the passengers were not ready. By the time the flight commenced, night had fallen and the area was experiencing dense fog, with visibility reported as being only tens of metres.
The crew and passengers boarded the aircraft, and the commander initiated the engines. After lifting into a hover, the helicopter moved to the centre of a paddock. The pilot flying intended to perform a vertical climb before transitioning to forward flight. As the aircraft gained speed, it reached a peak radio altitude of 125 ft agl. However, the aircraft then began a progressive nose-down pitch. Flight data indicates the aircraft reached a 25º nose-down attitude while descending at a rate of 2,400 ft/min. During these final seconds, the co-pilot provided two verbal warnings regarding the pitch attitude, and the data shows that full collective was applied.
The helicopter struck the ground in a rising field approximately 420 m from the takeoff point. The impact sequence involved the nose structure and landing gear hitting the ground, followed by the main rotor blades striking the earth. The aircraft then rotated and came to rest upright 63 m from the initial impact site. The accident resulted in 4 fatalities (two crew and two passengers) and the total destruction of the aircraft.
The investigation
The AAIB examined evidence from eyewitnesses, cockpit voice and flight data recorders, and video footage of the departure. Engineering inspections of the wreckage revealed that both engines were operating during the impact and the rotor head could turn freely. While the left fuel tank was leaking, the right tank remained intact. The investigation also confirmed that the tail rotor drive shaft was rotating during the impact sequence, despite the shaft failing at the base of the fin due to impact forces.
Findings
- The aircraft departed in conditions of dense fog with extremely low visibility.
- The helicopter entered a descent characterized by an increasing nose-down pitch.
- The application of full collective occurred simultaneously with the co-pilot's warnings regarding pitch.
- No technical malfunctions were identified by the investigation to date that could account for the accident.