With four peaks over 4,000 feet, including the 4,296-foot Ben Macdhui, the Cairngorms are Britain's loftiest mountain range. Weather in the Cairngorms for most of Monday afternoon was cold and bright with good visibility and light southerly winds, the Meteorological Office said. Snow and sleet were beginning to develop in the mountains. It is unusual for more than one U.S. military plane to crash on the same day, but fatal training accidents are by no means rare. On Feb. 12, two Army Black Hawk helicopters collided during a nighttime training session in Hawaii on Feb. 12, killing six soldiers.
Statistics show that, overall, U.S. military aviation has become safer in recent years.
V-22 Osprey crash last April that killed all 19 Marines aboard.