What happened
On 16 December 2012, a Diamond Aircraft DA 40 D Diamond Star, registration G-OCCL, was involved in a ground collision at Wolverhampton (Halfpenny Green) Airport. The aircraft was being used for a training flight, carrying a flying instructor and a student. After completing pre-flight inspections, the instructor and student taxied toward the airfield fuel bay.
As the aircraft moved through a section of the taxiway, the student pilot reported that visibility was obstructed by the low position of the sun. The instructor took control of the aircraft to continue the taxi. However, as the aircraft emerged from the shadow of a hangar, the combination of the low sun and moisture on the windscreen significantly impaired the instructor's view. While navigating a narrow passage between a fuel bowser and a fire service vehicle, the instructor failed to notice an unoccupied R44 helicopter parked at the fuel pumps. The DA 40 collided with the helicopter's tail at low speed.
The investigation
The investigation established that the aircraft had been moved outside its hangar earlier that morning. Due to the cold temperature of 2°C, moisture had accumulated on the windscreen. Although the instructor attempted to clear the interior of the screen using a glove and reached through the direct vision window to clear the exterior, the windscreen remained difficult to see through. The investigation also noted that the sun was positioned directly ahead, creating glare and reducing visibility to the left of the taxi route.