Mikoyan MiG-31: the Soviet Union's long-range interceptor

The Mikoyan MiG-31, NATO reporting name “Foxhound,” is a twin-engine, twin-seat interceptor built by the Soviet Mikoyan design bureau to intercept cruise missiles and low-flying targets, escort strategic bombers and cover the air defence gaps the MiG-25 could not reach. It replaced the Tupolev Tu-128 as the Soviet Union’s dedicated long-range interceptor¹ and remains in front-line service with the Russian Aerospace Forces, where it has taken on a second role as the launch platform for Russia’s Kh-47M2 Kinzhal hypersonic missile.

Design and development

The MiG-31 grew out of the limits of its predecessor: the MiG-25 “achieved high speed and altitude” but lacked manoeuvrability at interception speeds and was difficult to fly at low altitudes. Mikoyan’s answer, the Ye-155MP prototype, first flew on 16 September 1975. Though the new type bore a superficial resemblance to the MiG-25, it had a longer fuselage to accommodate the radar operator’s cockpit and was in many respects a new design. Its defining feature was an advanced radar capable of both look-up and look-down/shoot-down engagement¹, letting it track and destroy targets flying below it, something the MiG-25 could not do.

Serial production began in 1979 and the type entered service on 6 May 1981. Manufacturing continued until 1994, and 519 aircraft were built in total. The programme later took an unplanned turn: after radar engineer Adolf Tolkachev was found to have sold MiG-31 radar technology to the West¹, Mikoyan had to hastily develop a new radar for a follow-on model.

Specifications

The MiG-31 is 22.62 metres long with a wingspan of 13.456 metres and a maximum take-off weight of 46,200 kg. It carries a crew of two, a pilot and a weapon systems officer, seated in tandem. Power comes from two Soloviev D-30F6 afterburning turbofans, rated at 152 kN each with afterburner, which drive it to a cruise speed of around 2,500 km/h, roughly Mach 2.35, at altitude. Combat radius without refuelling is about 1,450 km at Mach 0.8¹; ferry range extends to 3,000 km, or 5,400 km with one aerial refuelling.

Variants

The baseline MiG-31 (500 built) was followed in 1990 by the MiG-31B, which added an in-flight refuelling probe and the upgraded radar made necessary by the Tolkachev leak. The MiG-31BM, which passed state testing in 2008, became the main modernisation standard: Russian sources say its combat efficiency is 2.6 times greater than the baseline aircraft, and it can track up to 24 targets and engage 8 of them at once with the new R-37 missile, which Russian data puts at Mach 6 and a range of up to 400 km. Two MiG-31D aircraft were built as dedicated anti-satellite platforms, armed with Vympel ASAT missiles and distinguished by a flattened fuselage underside and large winglets. The MiG-31K, a modified MiG-31BM able to carry the Kh-47M2 Kinzhal air-launched ballistic missile, had ten aircraft converted by May 2018; with its auxiliary power unit removed to fit the missile, it gave up its air-to-air role to become a dedicated attack aircraft. An intended successor, the MiG-31M, began development in 1984 and first flew in 1985 with a redesigned rounded windscreen, digital flight controls, CRT cockpit displays and six fuselage weapon stations, but only one prototype and six pre-production aircraft were completed before the Soviet collapse ended the programme. The newest variant, the MiG-31I, completed flight tests in April 2024¹ with reported in-flight refuelling capability and different engines, avionics and missiles.

Operators and service

The Russian Aerospace Forces is the type’s main operator, flying an estimated 85 to 131 MiG-31BMs as of 2020, plus 10 of the Kinzhal-armed MiG-31K, from regiments including those at Kansk, Perm, Monchegorsk and Khotilovo. Kazakhstan inherited 50 aircraft from the Soviet Union but retired the type in 2023 and put the fleet up for auction¹; Kazakh officials denied reports that any were sold to the United States.

Since Russia’s full-scale invasion of Ukraine began in 2022, MiG-31s have flown combat air patrols at high speed and high altitude, where Ukrainian fighters have lacked the range, speed or altitude to engage them, and have reportedly shot down several Ukrainian aircraft, mainly with the long-range R-37 missile. By October 2023, the Royal United Services Institute reported about six R-37M missiles being fired at the Ukrainian Air Force each day. Ukraine said a Kh-47M2 Kinzhal missile fired from a MiG-31K was intercepted by a Patriot air defence system on 4 May 2023¹.

Safety record

Losses have come from both accidents and combat. Chief test pilot Aleksandr Fedotov and navigator V. Zaitsev were killed in a MiG-31 during a test flight on 4 April 1984. A training crash near the Telemba proving ground on 26 April 2017 was later found, from a leaked government document, to have been caused by an R-33 missile fired in error from another MiG-31, with both crew ejecting safely; the inquiry flagged problems with the Zaslon-AM radar and Baget-55 fire control system as a risk for further accidental shootdowns. Further training crashes were recorded in Kazakhstan’s Karaganda region on 16 April 2020, in Russia’s Leningrad region on 8 April 2022, in Primorsky Krai on 2 December 2022, near Murmansk on 26 April 2023, and over Avacha Bay on 4 July 2023. In the war in Ukraine, three MiG-31BMs had been visually confirmed as lost as of 8 September 2024, including two destroyed on the ground at Belbek airfield on 15 May 2024; Ukraine claimed the destruction of a further MiG-31 at Belbek on 18 December 2025¹.

Similar aircraft

• Mikoyan-Gurevich MiG-25: the earlier Soviet interceptor the MiG-31 was designed to replace¹, sharing its basic layout but not its low-level performance.
• Grumman F-14 Tomcat: a comparable Cold War-era twin-engine, two-seat interceptor built for long-range engagement against bombers and cruise missiles.
• Tupolev Tu-128: the long-range interceptor the MiG-31 replaced in Soviet service¹.