 Although 13 of North Vietnam's flying aces attained their status while flying the MiG-21 (cf.three in the MiG-17), many VPAF pilots preferred the MiG-17 because the high wing loading of the MiG-21 made it relatively less maneuverable and the lighter framed canopy of the MiG-17 gave better visibility.However, this is not the impression perceived by British author Roger Boniface when he interviewed Pham Ngoc Lan and ace Nguyễn Nhật Chiêu (who scored victories flying both MiG-17 and MiG-21).