Summary and Key Points: In 1976, Soviet pilot Lt. Viktor Belenko defected with his MiG-25, revealing surprising technological gaps to Western intelligence. The Soviet Union soon developed a significantly more advanced successor—the MiG-31 Foxhound.
-Unlike the MiG-25, the MiG-31 featured a lighter, stronger airframe, powerful engines, and most notably, the groundbreaking Zaslon radar—the world’s first passive electronically scanned array (PESA).
-Capable of tracking ten targets simultaneously at long range, the MiG-31 radar proved far superior even to the U.S. F-14 Tomcat’s systems. Thanks to ongoing upgrades, the MiG-31 remains active in Russia’s air defense, underscoring Moscow’s enduring focus on radar technology and interception capabilities.
Why Russia’s MiG-31 Foxhound Still Flies Decades Later
In September 1976, a lone Soviet pilot serving at an Air Defense Forces (PVO) aerodrome in the Soviet Far Eastern Khabarovsk region, Lt. Viktor Ivanovich Belenko, shocked the intelligence world. He flew his Mikoyan MiG-25 fighter aircraft to a commercial airport on Japan’s Hokkaido Island and, on landing, promptly announced his defection.
At the time, it was the gold mine of defections. The US intelligence community’s assessment of the MiG-25 described it as the most formidable high-speed, high-altitude interceptor in the Soviet arsenal.
Once they got a look under the hood, US technical specialists who examined the aircraft on the ground in Japan found its actual design and onboard systems shattered some of the West’s illusions about Soviet military technology. The radar—while powerful—and other onboard electronics belonged to the vacuum-tube age.
Cooling of the avionics and other systems was accomplished not with a sophisticated nitrogen-based system but with pure grain alcohol. It was also a grade of alcohol that was so pure that officers from other nearby units would drive to the MiG-25 base and illegally buy liters of it for an upcoming banquet or holiday.
“The Russians have to be working on something that is more sophisticated than this,” said one of the American engineers who evaluated the MiG-25. Belenko told his US debriefers they were correct—that a new, improved airplane was coming soon.
The World’s Fastest Interceptor
In an unmarked building in northwest Moscow surrounded by a high-level security fence on Leningradskoye Shosse, a newer, more capable follow-on to the MiG-25 was actually in the works. The building was the Mikoyan Design Bureau, and the aircraft turned out to be the MiG-31—NATO Codename Foxhound.
The MiG-31, which outsiders noticed in the early 1980s at the top-secret Flight Research Institute (LII) outside of Moscow, differed from the MiG-25 in numerous respects. The MiG-25’s airframe was a more straightforward and hastily developed design constructed from 80 percent nickel, 11 percent aluminum, and 8 percent titanium. The MiG-31 airframe was considerably lighter—composed of 49 percent arc-welded nickel steel, 33 percent light metal alloy, 16 percent titanium, and two percent composites.
The lighter-weight advanced construction was not the only difference. The aircraft was powered by a pair of Perm/Soloviev D-30F6 engines—the best-performing Soviet fighter engine ever designed and with the highest dry thrust.
But, the most impressive aspect of the MiG-31 was its radar, the NIIP N007 Zaslon, a Russian word meaning “shield.”
The First of Its Kind Radar
This radar was the first-of-its-kind passive electronically-scanning array (PESA) in use with any nation’s air force. Its search range was 124 miles in the forward hemisphere and 56 miles in the rearward sector. It could track targets at ranges of 75 miles and was the first Soviet radar with fully functional look-down/shoot-down capability.
It could also track ten targets and then engage up to four simultaneously. The selection of targets did not require the pilot to do so manually, but the onboard Argon-15 digital mission computer could prioritize the firing sequence.
The radar was a technological marvel of its day and required almost every major Soviet defense electronics firm to participate in the effort. An immense effort was put into the program for the simple reason that the USSR defense posture called for an aircraft that could intercept any nuclear platform—either a bomber or a cruise missile—before it could fire on its target inside of the Soviet Union.
Like the US Navy’s F-14 Tomcat, the MiG-31 had a rear seat Radar Intercept Officer (RIO) to fire the aircraft’s Vmpel R-33 (AA-9) long-range air-to-air missile. Numerous comparisons were made between the two aircraft. Many suggest that the MiG-31 super-radar of the day plus its long-range missile are roughly the same in function and design as the F-14’s AWG-9 radar and Hughes AIM-54 Phoenix missile.
But Russian designers I spoke with several years ago from the Vympel missile design bureau pointed out that the dynamic between them was reversed—that the Zaslon was actually the much more capable radar of the two and the R-33 a less-sophisticated missile.
“Think of it this way,” said one of the firm’s senior designers. “With the MiG-31’s Zaslon, we designed the world’s most expensive revolver and used average-priced bullets. But with the F-14 the US did the opposite. You came up with the world’s most expensive bullets in the form of the Phoenix missile but used an average-priced AWG-9 revolver.”
Emphasizing the radar turned out to be the better choice. The F-14 was retired from service in 2006, but the MiG-31, through many upgrades and improvements to its avionics and radar, is still operational today with the Russian VKS.
MiG-31: A Photo Essay
MiG-31 from Russian Air Force. Image Credit: Creative Commons.
MiG-31. Image Credit: Creative Commons.
MiG-31 fighter. Image Credit: Creative Commons.
A Russian MiG-31 fighter jet equipped with a Kinzhal hypersonic missile flies over Red Square during a rehearsal for a flypast, part of a military parade marking the anniversary of the victory over Nazi Germany in World War Two, in central Moscow, Russia May 7, 2022. REUTERS/Maxim Shemetov
A Kh-47M2 Kinzhal ALBM being carried by a Mikoyan MiG-31K interceptor.
About the Author: Reuben F. Johnson
Reuben F. Johnson is a survivor of the February 2022 Russian invasion of Ukraine and is now an Expert on Foreign Military Affairs with the Fundacja im. Kazimierza Pułaskiego in Warsaw. He has been a consultant to the Pentagon, several NATO governments, and the Australian government in the fields of defense technology and weapon systems design. Over the past 30 years he has resided in and reported from Russia, Ukraine, Poland, Brazil, the People’s Republic of China and Australia.
