A breakdown in terrain avoidance responsibilities between two American pilots and an air traffic controller with the Royal Air Force caused a crash two years ago that killed both pilots, according to an Air Force Accident Investigation Board.

The determination was released Wednesday by the U.S. Air Forces in Europe public affairs office at Ramstein Air Base, Germany.

That breakdown in responsibility caused the pilots of the two F-15Cs, Lt. Col. Kenneth Hyvonen and Capt. Kirk Jones, to descend below safety altitudes without having “positive visual contact with the ground,” the report concludes.

The two jets, both from the 48th Fighter Wing, crashed into a snow-covered mountain in the Cairngorm range in western Scotland on March 26, 2001. Both men were killed.

The report’s release was delayed by a court-martial of the RAF controller, Flight Lt. Malcolm Williams, who was on duty at RAF Leuchars and talking to the pilots just before the crash. He was acquitted of charges that he was professionally negligent in his duties.

The court-martial heard testimony that Williams had returned from a leave on the day of the crash following the death of his father and that he created a “false sense of security” by telling the pilots it was safe to descend to 4,000 feet when the proper safe altitude was 6,000 feet.

Williams’ defense said he provided the pilots with a safe alternative route to the training area that was their destination, but they chose another path, which ended in their deaths.