service with the J/APG-1 active phased array radar. Able to intercept and destroy cruise missiles flying at extremely low altitudes. Variant differences The basic differences between other versions and the MiG-31BM are: The onboard radar complex of the MiG-31BM can track 24 airborne targets at one time, six of which can be simultaneously attacked by R-33S missiles. Modernized variants of the aircraft can be equipped with anti-radiation missiles Kh-31, Kh-25MR or MPU (up to six units), anti-ship Kh-31A (up to six), air-to-surface class missiles Kh-29 and Kh-59 (up to three) or Kh-59M (up to two units), up to six precision bombs KAB-1500 or eight KAB-500 with television or laser-guidance. Maximum mass of payload is . The MiG-31M, MiG-31D, and MiG-31BM standard aircraft have an upgraded Zaslon-M radar, with larger antenna and greater detection range (said to be against AWACS-size targets) and the ability to attack multiple targets – air and ground – simultaneously. The Zaslon-M has a diameter (larger) antenna, with 50–100% better performance than Zaslon. In April 1994 it was used with an R-37 to hit a target at distance. It has a search range of for a RCS target and can track 24 targets at once, engaging six, or for . Relative target speed detection increased from Mach 5 to Mach 6, improving the probability of destroying fast-moving targets. The MiG-31BM is one of only a few aircraft able to intercept and destroy cruise missiles flying at extremely low altitude. Cockpit The aircraft is a two-seater with the rear seat occupant controlling the radar. Although cockpit controls are duplicated across cockpits, it is normal for the aircraft to be flown only from the front seat. The pilot flies the aircraft by means of a centre stick and left hand throttles. The rear cockpit has only two small vision ports on the sides of the canopy. The presence of the WSO (weapon systems operator) in the rear cockpit improves aircraft effectiveness since the WSO is entirely dedicated to radar operations and weapons deployment, thus decreasing the workload of the pilot and increasing efficiency. Both cockpits are fitted with zero/zero ejection seats which allow the crew to eject at any altitude and airspeed. Armament The MiG-31's main armament is four R-33 air-to-air missiles (NATO codename AA-9 'Amos') carried under the belly. One GSh-6-23 cannon with 260 rounds. (The MiG-31's predecessor, the MiG-25 did not include a cannon.) Fuselage recesses for