HAMPTON, Va. (AP) -- U.S. Air Force investigators say extreme fogging in the cockpit caused a fighter plane to leave the runway at a Wisconsin airport after it landed.

The F-16C Falcon came to a stop about 300 feet away in a grass field.

The plane was on a training mission to an air show at Wittman Regional Airport in Oshkosh, Wis., when the accident occurred last summer.

The Air Combat Command Accident Investigation Board in Hampton, Va. said Tuesday that the pilot's visual cues were completely obscured by fogging caused by the aircraft's environmental control system.

Without those cues, the pilot didn't apply adequate aerobraking. Damage to the plane is estimated at $5.4 million.

The jet and pilot are assigned to the 100th Fighter Squadron, 187th Fighter Wing at Dannelly Field, Ala.