What happened
On 5 June 2014, a Cessna F172M Skyhawk, registration G-TRAX, was performing an aerial work flight when it struck power cables during its approach to Runway 28 at Derby Airfield. The aircraft had been flying from Glatton Airfield and joined the visual circuit via the downwind position.
During the final approach, the pilot was operating with full flaps at a speed of approximately 60 knots into a headwind of 15 to 20 knots. The pilot reported encountering wind shear while on short finals, which resulted in a rapid loss of altitude. The aircraft subsequently made contact with power lines that crossed the approach path. The impact caused the cables to snap, but they remained caught in the propeller. This entanglement induced a leftward yaw, leading the aircraft to impact the ground short of the runway threshold in a nose-low and right-wing-low attitude.
The pilot escaped the aircraft without injury. The accident caused damage to the aircraft's wings, nose structure, propeller, and nose landing gear, as well as damage to the power lines.
The investigation
Investigators examined the approach path for Runway 28 and noted that the airfield features a significantly displaced threshold. While the total length of Runway 10/28 is 453 meters, the available landing distance for Runway 261 was much shorter due to the displacement.
Records from the UK Aeronautical Information Publication indicated that telegraph wires and poles, situated at an elevation of 200 feet, crossed the approach to Runway 28. These wires were located approximately 195 meters from the start of the displaced threshold. Additionally, a commercial flight guide provided a specific caution regarding power cables being 30 feet above the approach path for this runway.
Weather data from East Midlands Airport around the time of the accident showed winds of approximately 10 to 11 knots, though forecasts had indicated the possibility of higher gusts.
Findings
- The aircraft encountered wind shear during the final approach, which caused a sudden and uncontrollable descent.
- The aircraft struck power cables positioned across the approach path for Runway 28.
- The entanglement of the cables with the propeller caused the aircraft to yaw and impact the ground before reaching the runway threshold.