Glider training for Royal Air Force cadets was undertaken at the site during 1939, with No. 28 Glider School using the site sporadically up until their disbandment in 1950. The airstrip was not used for any flying purposes during the Second World War, but may have been left as a decoy airfield to attract enemy bombers (though certain groups such as English Heritage state there is no evidence of this). Another decoy airfield was sited on the racecourse on the opposite side of the A170, north of the airfield. This was furnished with replica Whitley bombers and became a relief landing ground for RAF Dishforth. At least one Royal Air Force aircraft is recorded to have landed at Sutton Bank when all other airstrips in the Vale of York were fogbound. As the site was familiar to many German glider pilots, defensive ditches were dug out of the airfield by the British Army during the 1940s, as it was perceived as a Nazi invasion site. The Germans were world leaders in the sport of gliding and many had travelled to Britain to train British pilots during the 1930s. One had even spent two years at Sutton Bank in the late 1930s training other glider pilots. As the German use of parachutists and gliders was seen to good effect when they invaded the Low Countries, Sutton Bank was perceived as a risk and so plans were made to fortify the area and cover over the White Horse to prevent identifying the location from the air. The digging damaged the Iron Age fortifications.