Summary and Key Points - Top 4 Ideas: The Saab 37 Viggen, a Swedish Cold War-era fighter jet, proved its capabilities across multiple roles, including air-to-air combat, ground attack, and reconnaissance.

-With a speed of Mach 1.7 and the ability to carry 16,000 pounds of munitions, it served Sweden from 1971 until 2007.

-A notable achievement was its interception of an SR-71 Blackbird, the only known fighter to lock onto this high-speed U.S. spy plane, thanks to meticulous planning and training.

-Despite its slower speed, the Viggen's role in these non-confrontational intercepts showcased Sweden’s neutral defense readiness. The JAS 39 Gripen replaced the Viggen after its retirement.

Cold War Feat: The Saab 37 Viggen and Its SR-71 Interception

The Saab 37 Viggen is probably an aircraft you haven’t heard of. And yet, the Swedish fighter jet was an extremely capable aircraft that proved itself during the long years of the Cold War. 

The JA 37 Viggen 

The Saab 37 Viggen, or “Thunderbolt,” was a single-seat, all-weather fighter jet. 

The aircraft could carry almost 16,000 pounds of munitions on nine hardpoints, including air-to-air, air-to-air ground, and anti-ship missiles, as well as conventional bombs. 

The aircraft could reach speeds of Mach 1.7 ( or around 1,300 miles per hour), had an operational ceiling of 60,000 feet, and a combat radius of 620 miles.

Saab and the Swedish Air Force began working on the Saab 37 Viggen in the 1950s.

The aircraft made its first flight in 1967 and entered service in 1971. The last aircraft was retired in 2007. Overall, Saab produced approximately 330 aircraft of all versions. The Swedish Air Force replaced the Saab 37 Viggen with the JAS 39 Gripen. 

The were four versions of the aircraft: the Saab 37 was a fighter jet; the AJ 37 was a fighter bomber designed for air-to-ground operations; the SF 37 was a reconnaissance aircraft; and the SH 37 was a maritime patrol jet. 

The JA 37 Viggen’s Unique Feat: Catching the SR-71?

The Saab 37 Viggen has a unique achievement in the history of combat aviation. It is the only known fighter jet to have locked in on an SR-71 Blackbird spy plane. That was no easy feat. 

Designed for long-range secret flights over the Soviet Union, the SR-71 Blackbird could achieve speeds of approximately Mach 3.2 (or almost 2,500 miles per hour) and could operate at altitudes of 85,000 feet. The Soviet military had nothing to counter such performance.

The MiG-25 Foxbat fighter jet, which was the fastest in the Russian arsenal, could hit speeds of Mach 2.8 (or about 2,150 miles per hour). As such, when conducting its reconnaissance flights over the Soviet Union, an SR-71 Blackbird could simply accelerate to evade any incoming air defense missiles or Russian interceptors. 

So, the feat of the Saab 37 Viggen becomes that much more important. Although a fast fighter jet, the Swedish aircraft couldn’t come close to matching the raw speeds of the spy plane. So how did it do it? Planning and training. 

During the Cold War, Sweden was a neutral country—indeed, the Scandinavian nation only joined NATO very recently after the renewed Russian aggression in Ukraine—and intercepted both Soviet and NATO aircraft overflying its territory.

The U.S. Air Force planned its SR-71 Blackbird missions to overfly Sweden on their way to the neighboring Soviet Union. As such, the Swedish Air Force had data about these flights and started developing ways to intercept the American spy planes. Using specially trained squadrons of Saab 37 Viggens, the Swedish Air Force managed to surprise SR-71 Blackbird pilots a number of times and even lock on to the extremely fast spy planes.

But those interceptions weren’t confrontational, and in one instance, Saab 37 Viggen pilots actually helped a damaged SR-71 Blackbird. 

About the Author 

Stavros Atlamazoglou is a seasoned defense journalist specializing in special operations and a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ). He holds a BA from Johns Hopkins University and an MA from the Johns Hopkins School of Advanced International Studies (SAIS). His work has been featured in Business Insider, Sandboxx, and SOFREP.

All images are Creative Commons and/or Shutterstock.