Only 3 countries have managed to build 5th-generation fighters, but nearly a dozen are already working on 6th-gen jets

• Twenty years after the arrival of the first fifth-generation jet, only a few have entered service.
• Fifth-gen jets are still the most advanced, but countries are already working on the next generation.

Some 20 years after their first appearance in the skies, fifth-generation fighters remain both the most advanced and rarest aircraft in service.

Only four models from three countries — the US's F-22 and F-35, China's J-20, and Russia's Su-57 — have been officially introduced.

But many other countries are determined to have their own next-generation models. At least nine countries are already developing sixth-generation aircraft, either on their own or in cooperation with other countries.

Little is known about these programs, but the scale of the work being done shows that many countries expect sixth-gen jets to be a vital part of their fleets in the decades ahead.

5th and 6th generation

Exactly what makes an aircraft "fifth-generation" or "sixth-generation" is subject to debate.

Generally speaking, fifth-generation refers to aircraft that began development in the late 1990s or early 2000s, have a completely new design compared to fourth-gen jets, and emphasize low-observable, or stealth, features.

Sixth-generation characteristics are less defined, as no sixth-gen aircraft exist yet. (The recently unveiled B-21 bomber is billed as the world's first sixth-gen aircraft, but little is known about its capabilities.)

There is a general consensus that sixth-gen jets will have a number of new or advanced features, including a modular design that allows for seamless upgrades, comprehensive networking capability, the ability to work with drones, and, of course, stealth.

Producing aircraft with fifth-gen features requires advanced technological know-how, an advanced industrial base, and, most importantly, massive financial investment. Developing and procuring the F-35, for example, is estimated to have cost as much as $412 billion, which doesn't include operations and maintenance costs.

Consequently, most countries are sticking with fourth-gen models, buying fifth-gen jets from a country that has already developed them, or, in the case of the F-35, contributing to the program without taking a larger role in development and manufacturing.

As with fifth-gen jets, developing sixth-gen aircraft will require major investment, so many countries have teamed up to share the costs and reduce development time.

NGAD and F/A-XX

The US has two sixth-gen projects underway, one for the Air Force and one for the Navy. Both are officially referred to as Next Generation Air Dominance, or NGAD, but the Navy's aircraft is often called the F/A-XX.

The NGAD projects are top secret and little is known about them — not even which contractor will build them or what they will look like. Lockheed Martin, Northrup Grumman, and Boeing are believed to be competing to build the jets, and all have released illustrations of sixth-gen aircraft.

What is known is that NGAD will be more than a new fighter jet. It will be a family of systems meant to ensure US air dominance. The Air Force has acknowledged developing four technologies for the program, including variable cycle engines, new composite materials, and a new suite of sensors, including advanced radar, infrared sensors, and improved electro-optical cameras.

NGAD also includes unmanned aircraft being designed to complement the sixth-gen fighter. Dubbed Collaborative Combat Aircraft, the drones will be networked to the fighter and can be assigned missions, allowing the jet to deploy them while it engages other targets using new long-range weapons like the AIM-260.

The F/A-XX will have similar features, including the ability to network with unmanned systems, which fits into the Navy's goal of having 60% of its future carrier air wings be unmanned aircraft.

The Air Force said in 2020 that it had built and flown a full-scale NGAD prototype, though service officials say the program is still in its design phase. The Navy is believed to be in the concept refinement phase for F/A-XX.

The Air Force hopes to have NGAD in service by 2030, while the Navy hopes to have the F/A-XX in service within the same decade.

FCAS/SCAF

The Future Combat Air System is a sixth-gen jet project announced by France and Germany in 2017 and joined by Spain in 2019.

FCAS also intends to develop a family of systems for air dominance, with a sixth-generation fighter known as the Next Generation Fighter (NGF) at its center. The NGF will have a new engine, new weapon systems, advanced sensors and stealth technology, and the ability to link with unmanned aircraft and connect to an air-combat cloud network.

The jet is meant to replace France's Rafales and the Eurofighter Typhoons flown by Germany and Spain. There are also plans for a carrier-based variant for use on France's future aircraft carrier.

With an estimated cost of about $106 billion, FCAS is one of the largest joint European weapons programs ever.

FCAS is partly meant to give Europeans a European-made option for high-end stealth aircraft, especially in light of the increase in F-35 purchases by European countries. But it faces headwinds.

The first NGF flight was expected in 2027, with manufacturing starting in 2030 and full introduction in 2040. But disputes between the three contractors over workload and prime contractor status kept the project from moving to its next phase for two years.

The four companies appear to have resolved those issues, however. On December 16, they announced the signing of a $3.4 billion contract enabling them to proceed, with plans for initial demonstration flights by 2029.

Tempest and F-X

The NGF isn't the only European sixth-gen jet in the works. Tempest is an effort by the UK and Italy that began in 2015 and was officially unveiled in 2018.

The jet was to be the main product of a larger British-Italian program also coincidentally called the Future Combat Air System, but the project was renamed the Global Combat Air Program on December 9, when Japan merged its own sixth-gen F-X program with the Tempest.

The British Royal Air Force has said that Tempest will feature a host of advanced capabilities, including a next-generation flight-control system, the ability to operate with unmanned aircraft, advanced sensors and networking capabilities, and even a "wearable cockpit" in which pilots use virtual-reality helmets to operate the aircraft via interactive displays and controls.

Tempest's designers also want the fighter to be able to carry weapons that have not yet been developed, like hypersonic missiles and directed-energy weapons.

Japan, which has already bought US-made F-35s, began work on the F-X in order to avoid dependence on a foreign supplier. The jet is the first that Japan has tried to build on its own in 27 years and is meant to replace its aging F-2 fighters, which are set to retire in the 2030s. Tokyo had planned to introduce the F-X into service in 2035.

Plans for the F-X included fiber-optic flight controls, VR-style helmet-mounted displays, and advanced sensors and networking capabilities. Japan is also developing drones, called Combat Support Unmanned Aircraft, to be operated by the F-X pilot either as sensor-laden scouts or as armed combat drones.

Prior to the merger, Tempest appeared on schedule. It is now in the concept and assessment phase, and the full development and manufacturing phase is set to begin in 2025. On July 18, the British Ministry of Defense announced that a flight demonstrator was scheduled to fly in 2027. Official introduction is planned for 2035.

The specifics of the merger of the Tempest and F-X programs and their related projects is not yet clear, but combining the programs could open additional export markets to the final product.

China and Russia

Unsurprisingly, no sixth-gen fighter programs are as secretive as China's and Russia's.

In 2019, Wang Haifeng, chief designer for China's state-run Chengdu Aircraft Industry Group, said that China had begun research for a next-generation fighter and that it could arrive as soon as 2035.

The future jet could have drone-teaming capability, use artificial intelligence and omnidirectional sensors, and be armed with directed-energy weapons, Wang said, according to media reports.

Gen. Mark Kelly, head of the US Air Force's Air Combat Command, said in September that China's sixth-gen aircraft development is "on plan" and that US and Chinese designers have similar views about sixth-gen technology.

"They see it greatly the way we see it, so an exponential reduction in signature, an exponential acceleration in processing power, and the ability to iterate in terms of open-mission systems, to be able to essentially reprogram at the speed of relevance," Kelly told reporters at the Air & Space Forces Association conference. "The differences, I think, are nuanced. They're really kind of small."

Even less is known about Russia's sixth-gen program. Moscow has announced "next-generation" or "sixth-generation" projects in the past, including an unmanned fighter in 2013. Moscow also announced blueprints for a sixth-generation fighter in 2016.

In January 2021, state-owned military technology conglomerate Rostec announced it was developing a next-generation replacement for the MiG-31, dubbed "PAK DP." It is often referred to as the MiG-41, but little is known about its capabilities and specifications.

While China is making heavy investment in military aviation, Russia's ability to develop next-generation jets may be shrinking. Work on Russia's Su-57 fifth-gen jet was already troubled, and sanctions imposed on Moscow over its attack on Ukraine will likely disrupt its aerospace industry for years to come.