What happened
On the evening of 13 March 2014, an Agusta AW1s9, registration G-LBAL, was prepared for a private flight from Gillingham Hall, Norfolk, to Coventry Airport. Although the departure was originally scheduled for 1830 hrs, the flight did not commence until approximately 1924 hrs due to passenger delays. By the time of departure, the area was experiencing dense fog with visibility reduced to tens of metres.
Following a vertical climb and a hover-taxi within a paddock, the pilot flying began a transition to forward flight. As the aircraft gained speed, it reached a peak radio altitude of 125 ft agl. However, the aircraft then entered 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 issued two verbal prompts 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 location. The impact sequence involved the nose gear and lower structure hitting the ground first, followed by the main rotor blades striking the earth. The aircraft then moved through a row of hay bales before coming to rest upright.
The investigation
The AAIB examined wreckage, eyewitness accounts, and data from the cockpit voice and flight data recorders. The investigation confirmed that there were 4 fatalities (two crew and two passengers) and that the aircraft was destroyed.
Engineering analysis of the wreckage revealed that the engines were operating during the impact and the rotor head could turn freely. While the left fuel tank leaked, the right tank remained intact. The investigation also noted that the tail rotor drive shaft had failed due to impact damage but was found to have been rotating during the accident sequence. No technical malfunctions were identified during the initial examination of the aircraft's systems or components.