The generational monikers bestowed on fighter jets aren’t quite as definitive as the people arguing in the comments below most articles tend to think. The corporations that design and build these jets, the military forces they’re operated by, and the analysts who spend their days pouring over comparisons and tech schematics may all provide you with a slightly different version of what it really means to be a fifth-generation fighter — and for good reason. There just isn’t any overarching governing body with the authority to tell American, Chinese, Russian and other industries what to call their planes.

Despite a lack of formal generational requirements, you’ll often find the industry has a way of balancing itself through the cost of available technology. Fifth-generation fighters, for instance, are widely accepted as aircraft that were designed with stealth intrinsic to the air frame, boasting advanced networking capabilities, and having efficient enough engines to “super cruise,” or maintain supersonic speeds without keeping their afterburners engaged. Technically, there are other qualifications, too, but neither Russia nor China’s “fifth generation” fighters currently meet even that third basic criteria, and yet their governments, the media, and most of the world still call them “fifth generation” fighters.

The point is, what makes for a new generation of fighters isn’t always that easy to pin down in lofty conversations about the future — but that’s precisely what the U.S. Air Force is currently working on with its Penetrating Counter Air (PCA) program.

The PCA program is the Air Force’s plan to begin fielding a sixth-generation air superiority fighter sometime in the 2030s. For those who may be hazy as to what differentiates an air-superiority fighter from the multi-role qualifier usually adorning the F-35, the concept is simple enough: an air superiority fighter is purpose-built to engage with enemy aircraft. Multi-role fighters, on the other hand, often compromise acrobatics or speed in favor of absorbing other mission requirements, like close air support. The U.S. Air Force currently employs the world’s first fifth generation fighters (F-22 Raptor) and a sizable fleet of older but faster F-15s to fill this role.

The Air Force has started prototyping its next generation fighter: Here's what we know:
F-22 Raptors fly in formation with an F-15 Eagle (USAF)

So what kind of crazy new technology will the sixth-gen PCA fighter bring to the table? To a large extent, that’s exactly what the Air Force is trying to figure out. Everything from drone swarms to hypersonic capabilities have been floated as potential advancements that might find a home on the PCA, but to date, many of these technologies remain firmly relegated to the drawing board. Hypersonics, for instance, is a technology the United States is still working on for missiles, with a long way to go before the scramjet technology being developed for applications like the SR-72 (the Blackbird’s successor) can find its way onto a new fighter. Notably, the SR-72 is expected to be unmanned, in large part because of biological stresses that would accompany traveling at speeds in excess of Mach 5.

One thing the Air Force knows for sure is that it expects the network capabilities of these fighters to grow exponentially into the new generation.

The Air Force has started prototyping its next generation fighter: Here's what we know:
Artist’s rendition of a 6th Generation fighter (Boeing)

“We are moving into a future where aircraft need to be looked at as not just elements of their own, but as a system of information nodes – sensor-shooter effectors. It is about creating an entire system of systems that is self-forming and self-healing with a greater degree of awareness than an adversary can achieve, and a much greater degree of survivability,” Gen. David Deptula, former planner of the U.S. air attacks in Operation Desert Storm and current dean of the Mitchell Institute for Aerospace Studies, told Warrior Maven.

It’s also all but certain that new fighters will take stealth to far greater extreme than even the sneaky F-35, placing a larger emphasis on heat distribution to mitigate weapons that utilize infrared heat signatures to locate and lock onto encroaching aircraft. However, despite being aimed at air-to-air engagements, the PCA may not end up smaller or more acrobatic than previous jets. There’s a growing contingent within the aviation community that believes dog fighting is a thing of the past. They argue that a bigger, heavier, and stealthier plane can expand on the F-35’s tactical strategy of engaging with opponents from behind the horizon through networked targeting assets and an even more advanced sensor suite. In this vision of the future, carrying more weapons to engage with opponents before they can reach you may be more valuable than being able to out-maneuver them once they get there.

The Air Force has started prototyping its next generation fighter: Here's what we know:
(USAF)

In fact, there’s a chance the air superiority fighter of the future may not be just one fighter at all.

“When you look at — through the lens of the network — and you look at air superiority as a mission, as a family-of-systems approach, you can see why you don’t hear me talking a lot about a replacement, A for B,” Air Force Chief of Staff Gen. Dave Goldfein told Defense News last March.

“Because the replacement may not be a single platform, it maybe two or three different kinds of capabilities and systems. And so as we look at air superiority in the future, ensuring that we’re advancing to stay ahead of the adversary, we’re looking at all those options.”