In late January a Russian MiG-31 jet fighter was lost due to unspecified equipment failure. The air force grounded all 120 MiG-31s until the exact cause could be determined. The most likely culprit is age which is why in late 2015 the air force received $378 million to upgrade another 50 of the older MiG-31s to the MiG-31BM standard. Unfortunately the recent crash was of a BM model as were some previous crashes. The latest crash was not unexpected. There have already been problems with recently refurbished MiG-31s. The most common problem has been the engines although one crash was due to landing gear problems. The refurbishment includes the D30F6 engines, which were tweaked and upgraded to make them more powerful, efficient and reliable. Yet there have been several crashes involving these upgraded engines. In December 2013 Russia grounded all 122 of its MiG-31 fighters after one of them crashed because both of its engines failed.
Russian air force officials are very disturbed because these recently refurbished MiG-31s keep crashing. The latest round of upgrades for most of its MiG-31s, to the new MiG-31BM standard, was supposed to improve reliability, as well as performance. The MiG-31BM upgrades will take the rest of the decade to complete. The upgrade also includes a new radar with a range of 320 kilometers and the ability to simultaneously track up to 10 targets. But without reliable engines and other components it’s all for naught. It’s the engines that worry air force generals and pilots the most. The BM upgrade is supposed to allow MiG-31s to remain in service until 2030.
Russian high-performance jet engines, like those used in fighters and bombers, have long been notoriously unreliable. The end of the Cold War in 1991 gave Russia access to Western manufacturing and components technology that was supposed to fix those Soviet era problem. It did, but not enough and not quite yet for military equipment. Russian jet engines are still notably inferior to their Western counterparts, especially when it comes to reliability.
Meanwhile the MiG-31BM upgrades come just in time as the elderly MiG-31s are in bad shape. The MiG-31 is itself an upgrade of the MiG-25 design, which was developed to deal with the American B-70 bomber. When the United States cancelled the B-70 in 1967 the Russians kept going with the MiG-25 and turned it into a reconnaissance aircraft. The B-70 got axed because it was too expensive and it was realized that the future was in bombers that came in low and fast rather than high and even faster.
The MiG-25, on the other hand turned out to be an excellent recon aircraft. It was able to fly higher and faster than other fighters used for recon although not as high as the American U-2 or SR-71. But the United States did not sell those aircraft to anyone, while Russia made a lot of money selling MiG-25s to anyone with enough cash. Russia also made a lot of money training the two man crews required for each exported MiG-25.
The MiG-31 fixed a long list of MiG-25 problems and was turned into a very impressive interceptor. The 46 ton aircraft has passive sensors (which have a range of 200 kilometers) and radar guided R33 missiles, with a range of 150 kilometers. Other missiles are carried, as well as smart bombs. The MiG-31 is not very maneuverable but it is fast (able to sprint at up to 3,200 kilometers an hour). Like the original MiG-25 it does not have much range (a 720 kilometer combat radius).
The MiG-31 appeared in the 1980s and the current version, the MiG-31M, is actually an accumulation of upgrades that have been under way since the Soviet Union collapsed in 1991. Since then, about 200 of the remaining 350 MiG-31s have been upgraded or are in line for the work if the cash is available. In the last few years, the MiG-31 fleet has gotten a lot more money and readiness (for combat) has gone from under 25 percent to over 75 percent. But only about 180 MiG-31s remain flyable and only 120 are actually in service. Russia is having a growing problem with obtaining sufficiently competent ground support personnel and civilian technicians that can handle upgrades and major maintenance.
About 500 MiG-31s were built in the 1980s and these aircraft remain the mainstay of Russian air defenses, at least as far as interceptors go. But the MiG-31 fleet is spread thin across Russia's vast borders and squadrons tend to be concentrated in areas where they might encounter high performance intruders (China and Europe). There are about 80 MiG-31s in storage and these can be refurbished and upgraded if need be.
In early 2013 Russia revealed that only about 16 percent of its MiG-31 interceptors were on alert at any time, ready to take off and confront aerial intruders. A larger proportion of the 240 Su-27s are on alert as well. The high-flying and extremely fast MiG-31s are able to catch just about any type of aircraft. The Su-27 comes along to back up the Mig-31s and protect them from any fighters. The MiG-31 is optimized for quick interception, not prolonged air combat.
Russia is covering 20,000 kilometers of land borders with fewer than 600 fighters. Worse yet, most of the Cold War era radars along the borders are elderly, unreliable and frequently off-line. The radar network is being rebuilt, but that will be taken care of more quickly than rebuilding the jet interceptor force. Actually, Russia will probably never have the Cold War size interceptor force (2,300 fighters) that existed in 1991. The only survivors of that are the MiG-31s and Su-27s.