What to expect from the US Air Force’s sixth-generation fighter jet

On May 18, the United States Department of the Air Force announced that it is looking to award a contract for the Next Generation Air Dominance Platform in 2024. The name, shortened to NGAD, is a jumble of Pentagon concepts, obscuring what is actually sought: a novel fighter jet representing the newest era of military aircraft—a sixth-generation fighter.

“The NGAD Platform is a vital element of the Air Dominance family of systems which represents a generational leap in technology over the F-22, which it will replace,” Secretary of the Air Force Frank Kendall said in a release. “NGAD will include attributes such as enhanced lethality and the ability to survive, persist, interoperate, and adapt in the air domain, all within highly contested operational environments. No one does this better than the U.S. Air Force, but we will lose that edge if we don’t move forward now.”

The solicitation to industry for the NGAD is classified, making the details of what, exactly, the Air Force wants hard to know at this time. But jet fighters have, for decades, been classified into generations. So what makes a fighter generation, and what makes a sixth-generation fighter?

“In calling NGAD a sixth-generation fighter, that’s an important signal that it’s moving into a new level of capability, and it has to, because the threats are really evolving,” says Caitlin Lee, senior fellow at Mitchell Institute for Aerospace Studies.

Aircraft generations, explained

Fighter planes date to the first World War as a distinct concept, and ever since that time observers have grouped fighters into generations, or models built at similar times around similar technologies. Fighter evolution in war happened rapidly, as the first exchanges of pistol-fire between the pilots of scout planes gave way to aircraft built for combat, with dedicated machine guns firing first around and then even through propellers. As hostile planes got better, new aircraft were built to let pilots win fights. Once enough of these changes were accumulated in new models of planes, those aircraft could be grouped by sets of features into different generations.

This is true for the earliest fixed-wing and biplane fighters, up through the piston-powered patrollers of World War II and into the jet era. In October 1954, Popular Science showed off four fighter generations flying in formation for ceremonies at an Air Force gunnery competition. This snapshot of generations captured two propeller-driven planes: the SPAD biplane from World War I and the F-51 fighter from World War II. They are joined by two distinct jet fighters: the F-86 Sabre, a type which saw action in the Korean War, and F-100 Super Sabre, a model that would go on to see action in the Vietnam War.

The attributes that go into an aircraft generation

What separates fighter generations, broadly, is their speed, weapons, sensors, and other new features as they become part of the overall composition of a plane. Sticking to jets, fighters with that method of propulsion have gone from straight-wing planes flying at top speeds below the sound barrier, with guns, unguided rockets, and bombs, all the way to sensor-rich stealth jets capable of carrying a range of anti-air and anti-ground missiles.

There is no one agreed-to definition of exactly what fighter generations are, though jet fighters are generally grouped separately from propeller predecessors. Historian Richard Hallion expressed a version, published in the Airpower Journal’s Winter 1990 issue, that outlines six generations as defined primarily by speed and maneuverability. Hallion’s definitions precede not just the Next Generation Air Dominance plane, but also the F-35 and F-22, which have become widely accepted as definitive fifth-generation fighters.

The jet fighter generations

While there’s debate about the specifics of what jet fighters fall in what generations, below is a rough overview of the generations, in order. This list is derived from one put forth in 2009 by John Tirpak, the editorial director of Air & Space Forces Magazine.

First generation

Feature: The propulsion comes from jet engines. Weapons, wing shapes, and sensors are similar to preceding and contemporary propeller-driven plane designs.
Models: Germany’s Me 262, which saw action in World War II. The P-80 Shooting Star, flown by the United States from 1945 to 1959.

Second generation

Features: The wings are swept backwards, planes are now equipped with onboard radar, and they are armed with missiles.
Models: The F-86 Sabre, flown by the US in Korea, and the MiG-15, flown by China and North Korea in the Korean War.

Third generation

Features: The jets can now achieve supersonic speed for short bursts and are equipped with missiles that could hit targets beyond line of sight.
Models: The MiG-21, designed by the USSR and still in service today, and the F-4 Phantom, developed for the US Navy and still in service with a few countries today.

Fourth generation

Features: These jets have reduced radar signatures, better radars, and even more advanced missiles.
Models: France’s Mirage 2000, a delta-wing fighter still in service today, and the F/A-18, used by the US Navy and Marine Corps. Plus, the US Air Force’s F-15 and F-16.

Fifth generation

Features: Jets are built for stealth, use internal weapons bays, fly with high maneuverability, have better sensors, and have the ability to sustain cruise at supersonic speeds.
Models: The F-22 and F-35 family developed by the US, and the J-20 made by China and the Su-57 developed by Russia.

Zooming in on fifth- and sixth-generation fighters

In 2009, Tirpak examined the possibility of what a sixth-generation fighter might be, in part by speculating on new technologies it could incorporate, but also by defining what came before. Writing now over a decade ago, Tirpak expected the post-F-22 generation of fighters to be even stealthier, more efficient, networked with other vehicles, equipped with better sensors, possibly change its shape mid-flight, use laser weapons, and even be optionally crewed.

Tirpak defined a fifth-generation fighter as having “All-aspect stealth with internal weapons, extreme agility, full-sensor fusion, integrated avionics, some or full supercruise,” and pointed to the F-22 and F-35 as examples.

To unpack the jargon above, “stealth” is a set of technologies, from the coating of the plane to the shape it takes, that make it hard to detect, especially with radar. Sensor fusion combines information from a plane’s sensors, like targeting cameras and radar, as well as other avionics, to create a fuller picture of the environment around the aircraft. “Supercruise” is flight at above supersonic speed, for sustained time, without having to dump extra fuel into the engines, a previous way of achieving supersonic bursts.

All of these changes are responses to the new threat environment encountered by previous fighters. Stealth is one way for plane design to mitigate the risk from advanced anti-air missiles. Enhanced sensors are a way to allow fighters to see further and better than rival aircraft, and rival air-defense radars. Fighter design is about both building with the threats of the day, while anticipating the threats of the future, and ensuring the plane is still capable of surviving them.

The sixth-generation fighter will also be a platform

In announcing the solicitation for the Next Generation Air Dominance, the Air Force didn’t name it as a fighter, but as a platform. It is reasonable to assume it will perform fighter-like roles and have a fighter-like shape. It is, after all, replacing the F-22, which is a fighter built for air superiority, or winning fights against other fighters. The use of “platform,” however, indicates that instead of looking to the last century of air-to-air combat, the Air Force is thinking about the vehicle in a broader role than just an aircraft that fights aircraft.

One way to think of this is that the NGAD will be one among several kinds of aircraft the Air Force intends to use in the future, the way it might use wings of fighters today. This could include fighting alongside the Collaborative Combat Aircraft (CCA), a combat drone the Air Force plans as part of its Next Generation operations model.

“What’s next-generation about CCA is that they will have more autonomy than the current UAVs in the Air Force inventory like Reaper. And the question is how much more autonomy will they actually have,” says Lee. “And I think what the Air Force is interested in is starting with having that manned fighter aircraft, whether it’s NGAD or something else, be able to provide inputs and certainly oversee the operations of the CCA.”

Incorporating other aircraft, especially more expendable autonomous aircraft, into the operations of a fighter wing can mitigate one of the biggest threats to fighters in the present day, which is that fighters are expensive and hard to replace. Adding an extra layer of uncrewed aircraft, ones that can fly a little closer and take on a little more risk, can ensure that the sixth-generation fighter behind the drone escort lives to fight another day.

Ultimately, what defines the Next Generation Air Dominance platform, or the sixth-generation fighter, will be that it is designed to meet and defeat threats that have emerged since the previous generation of fighter jets, while at the same time doing the job of a fighter jet—which is ensuring the Air Force can put weapons where it wants to.