These aircraft are scheduled to be phased out by 2030.[148] Mikoyan-Gurevich MiG-21: the MiG-21 serves as an interceptor aircraft in the IAF, which phased out most of its MiG-21s and planned to keep only the 125 aircraft upgraded to the MiG-21 Bison standard.[157] The phase-out date for these interceptors has been postponed several times.