The Me 262's top ace was probably "Hauptmann" Franz Schall with 17 kills, including six four-engine bombers and ten P-51 Mustang fighters, although fighter ace "Oberleutnant" Kurt Welter claimed 25 Mosquitos and two four-engine bombers shot down by night and two further Mosquitos by day. Most of Welter's claimed night kills were achieved by eye, even though Welter had tested a prototype Me 262 fitted with FuG 218 "Neptun" radar. Another candidate for top ace on the aircraft was "Oberstleutnant" Heinrich Bär, who is credited with 16 enemy aircraft while flying Me262s out of his total of 240 aircraft shot down.