4th, 5th, 6th generation fighter jets explained – What these labels tell us

Why fighter jet generations are a useful shorthand to understand the evolution of technology and doctrine but also why dividing lines become fuzzy and gets hijacked by competing interests.

New Delhi: Fighter jet “generations” sound neat and simple on paper, but in reality they are more of a shortcut than a strict rule. The labels – 4th, 5th, 6th generation – help describe how combat aircraft have changed over time, but they don’t always cleanly separate one era from another.

The idea of grouping fighter jets this way first came in 1990, when air historian Richard P. Hallion suggested a classification system. He described early jets as subsonic aircraft that could not break the speed of sound, followed by transonic jets that could reach it and supersonic jets that could go beyond it, before moving to later designs built for better speed, agility and combat performance. His exact system did not stick, but the concept of “generations” did, and it soon became a common way to talk about fighter development.

The idea gained even more traction when the F-22 Raptor entered development. For the first time, a single aircraft was used to define an entire generation. Calling it the world’s “first 5th-generation fighter” also helped explain its high cost and advanced capabilities. Other countries later adopted the same language, including Russia, where the term also carried marketing value.

Early fighter jet generations

The first generation of fighter jets appeared in the late 1940s and early 1950s. These aircraft were basic in design, with early jet engines, simple or no radar and only gun-based weapons. For instance Me 262, Gloster Meteor, F-86 Sabre and MiG-15.

The second generation came in the mid-1950s to early 1960s. These jets introduced swept wings for faster flight, early radar systems and air-to-air missiles. Aircraft such as the MiG-21, Mirage III, English Electric Lightning and F-104 Starfighter were built mainly for high-speed interception to counter bombers.

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From the mid-1960s to the 1970s, the third generation improved radar, missile systems and maneuverability. The F-4 Phantom II became the most widely used aircraft of this era, along with jets such as the MiG-23 and Mirage F1. These aircraft began moving toward multirole capabilities, though most were still built around specific missions.

4th-generation fighters

Fourth-generation fighters form the backbone of most air forces even today. They appeared from the late 1970s and brought major changes in design and performance.

Fly-by-wire controls, advanced radar systems, better maneuverability and true multirole capability became standard. Aircraft such as the F-16, F-15, MiG-29, Su-27, Mirage 2000 and F/A-18 belong to this group.

Over time, these jets were upgraded with better electronics, sensors and networking systems. This led to the informal “4.5 generation” label for aircraft such as the Rafale, Eurofighter Typhoon, Gripen E, F-15EX and Su-30 variants. The term is used in media and industry, but it is not a strict military classification.

5th-generation fighters

Fifth-generation fighters were defined by the F-22 Raptor and built around stealth from the start. These aircraft use internal weapon bays, advanced sensor fusion and networked systems that allow them to share data across platforms.

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The most widely accepted 5th-gen fighters include the F-22 and F-35 from the United States, China’s J-20 and newer J-35. Some analysts place Russia’s Su-57 closer to an advanced 4th-generation or transitional design due to differences in stealth and sensor integration.

At this stage, fighter jets became less about traditional dogfights and more about detection, data sharing and electronic warfare.

6th-generation fighters

Sixth-generation fighters are still in development, and there is no fixed definition so far. Most designs point toward manned-unmanned teaming, AI-assisted systems, longer-range sensors, adaptive engines and deeper networking.

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Programs such as the US F-47 and F/A-XX, Europe’s Tempest and FCAS and Chinese next-generation projects all fall into this evolving category. Northrop Grumman has even referred to the B-21 bomber as a 6th-generation platform. It shows how the boundaries between fighter and bomber roles are starting to blur.

Higher generation doesn’t always mean better

Despite the labels, a higher generation does not automatically mean an aircraft will win in combat. Performance depends on how it is used and what systems support it.

Western jets operate inside a larger network that includes AWACS aircraft, satellites and shared targeting systems. This allows aircraft like the F-15EX to fire weapons based on external sensor data without switching on its own radar.

In contrast, analysts point out that aircraft such as the Su-57 may perform differently depending on whether they are operating alone or within a support network. This is why generation labels only tell part of the story.

In modern air combat, the aircraft is important, but the system it is plugged into matters just as much.