Incident Summary
A pilot conducting a low-altitude practice aerial application flight reported losing depth perception between the snow-covered ground and an overcast sky. As a result, the airplane impacted the ground and came to rest after sliding approximately 500 feet.
Aircraft Damage
The airplane sustained substantial damage to its right wing and fuselage.
Pilot's Report
The pilot stated that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.
Environmental Conditions
The flight took place in conditions described by the Federal Aviation Administration's pamphlet, "Flying in Flat Light and White Out Conditions," which notes that flat light is an optical illusion, also known as "sector or partial white out." It is not as severe as "white out" but causes pilots to lose depth-of-field and contrast in vision. Flat light conditions are usually accompanied by overcast skies, which inhibit visual clues. Such conditions can occur anywhere in the world, primarily in snow-covered areas but also in dust, sand, mud flats, or on glassy water. Flat light can obscure terrain features, making it difficult to distinguish distances and closure rates. The pamphlet states that with proper training and planning, it is possible to safely operate an aircraft in flat light conditions.