A pilot whose light aircraft collided with the red monoplane of a pilot from Leicestershire may have had difficulty seeing due to the position of the sun.
Martin Hickin died after the collision at Stoughton airfield near Leicester in December 2011.
A report by the Air Accidents Investigation Branch (AAIB) also said the 48-year-old pilot of the Taylorcraft BC12D, which collided with Mr Hickin's monoplane, may also have had sighting difficulties due to the lack of contrast between the other aircraft and the surrounding countryside, adding the two aircraft collided because their respective pilots either did not see the other aircraft or did not see it in time to take effective action.
The AAIB report said Mr Hickin's monoplane "became uncontrollable" after the collision and crashed to the ground. The 48-year-old pilot and passenger of the Taylorcraft were injured after making a forced landing.
Shortly after the accident, the family of Mr Hickin said he was an experienced pilot who had loved flying since his youth. They said he had been a civilian glider pilot instructor for the RAF in his 20s. The family also said they were relieved that the two people in the other plane survived the "horrific" mid-air collision.