Key point: The Swiss air arm famously operates F/A-18s and F-5s from highly-defensible, secret mountain bases.

The Swiss air force is beginning to test foreign warplane designs as part of a lengthy and much-delayed, $8-billion effort finally to replace the air arm's old Northrop Grumman F-5E/F Tiger fighters.

On April 12, 2019, two Eurofighter Typhoons --  an FGR4 single-seat, multi-role variant and a T3 two-seat trainer, both operated by British Aerospace -- reportedly flew missions from Payerne.

"A Swiss evaluator was noted flying in the two-seater," Scramble magazine reported.

Switzerland is testing five different aircraft. Beside the Typhoon, the candidates including Boeing's F/A-18E/F Super Hornet, Dassault's Rafale, Lockheed Martin's F-35A Lightning II and Saab's JAS-39E/F Gripen.

"Between April and July 2019, the five candidates will be in Switzerland for aerial and ground tests for a period of two weeks each, with public viewing opportunities," according to Scramble.

These tests will complete the same program with the objective to check the capacities of the aircraft and the data of the offers submitted by the different manufacturers. Each candidate will perform eight missions with specific tasks.

Performed by one or two aircraft, these missions will consist of 17 take-offs and landings. They will focus on operational aspects, technical aspects and special features.

Assessments will continue through 2020 before a decision is made. Armasuisse has asked the manufacturers to submit pricing for 30 or 40 aircraft, including logistics and guided missiles, among other criteria for the bids.

The air force hopes to begin inducting the new planes no later than 2025 in order to remedy a dire shortfall in active fighters. In April 2019 the Swiss air force is down to just 10 ready fighters with full-time pilots.

The crisis is the result of the Swiss public's decision in a 2014 referendum to reject the air force's proposal to buy 22 new fighters. Now the Swiss air arm must make do with fewer planes and keep those planes in service longer. The knock-on maintenance effects drastically have reduced the number of available planes.

The Swiss air force as recently as 2018 possessed 30 F/A-18C/D Hornets dating from the 1990s plus 53 1970s-vintage F-5E/Fs. Full-time pilots fly the Hornets. Part-time reservists pilot the F-5s.

In 2014 the air arm proposed to replace the Tigers with 22 Swedish-made JAS-39 Gripen fighters at a total cost of $3.1 billion. But 53 percent of the Swiss public voted against the acquisition. The air force proceeded with its plan to retire the F-5, however.

The service in 2019 plans to remove from service 27 Tigers. The Tigers that remain will perform limited duties. “The air force flies the F-5 Tiger as the aggressor during exercises with the F/A-18, and the single-engine jet also makes up the Patrouille Swiss air display team,” Defense News reported. “The 26-strong fleet of F-5s no longer flies air patrol.”

With the F-5 force shrinking and flying part-time, the Swiss air force increasingly relies on its 30 F/A-18s. To last that long, the F/A-18s need structural upgrades. And that's what's driving the fighter shortage. The Swiss parliament approved a service-life extension for the F/A-18 fleet that should extend each jet's lifespan from 5,000 to 6,000 flight hours.

"The Swiss company RUAG ... has upgraded a first aircraft as a prototype in the summer of 2018," Scramble reported. "This job was done within four months. However, for the next five Hornets, this work will take much longer than expected. This is due to previously unknown and only partially resolved problems from the production period at the end of the '90s."

The work has left just 10 Hornets in service. "Two aircraft were constantly on quick-reaction alert and four aircraft were participating in the Frisian Flag exercise at Leeuwarden [in] The Netherlands. So four aircraft were available for regular tasks like training. The Swiss air force and RUAG are doing everything they can to increase the readiness, as both have stated."

The Swiss air arm famously operates F/A-18s and F-5s from highly-defensible, secret mountain bases. Defense News in March 2018 witnessed one mountain deployment. "The pilot flies an air patrol, returns and lands just outside the base. A crane rotates the F/A-18 and places the fighter on a platform, which brings the plane back into military silence under the mountain. The stealthy doors close until the next flight."

The new fighter might not fly from the same secret bases, a Swiss officer told Defense News. "Asked whether the upcoming Swiss tender as part of the drive sets a key requirement for a fighter to be able to enter that base, the officer said it was not essential but would be nice to have."

David Axe serves as Defense Editor of the National Interest. He is the author of the graphic novels  War Fix, War Is Boring and Machete Squad. This first appeared last year.

Image: Reuters.