 Some of these aircraft were used against USAAF bombers by a special "Shinten Seiku Tai" (air superiority unit), comprising at least four aircraft, that was part of "47th Sentai", based at Narimasu airfield in Tokyo.Pilots from such units attempted to shoot down B-29s and, once their ammunition was expended, to ram them – effectively a suicide attack.While the concept appeared straightforward, ramming a B-29 at high altitudes was difficult to achieve in practice.