"Fifth-generation" and "sixth-generation" have become buzzwords for modern fighter jets. The concept of there being different generations of fighter jets appeared in the 1990s, and it should be stressed that there is no hard and fast definition of what it takes for a combat jet to belong to a particular generation of fighter jets (which is partly why there is debate about whether a given aircraft really is a fifth-gen fighter). Fighter jets are placed into generations in an attempt to classify the major technological leaps in the development of the jet fighter.

As an aircraft goes from one generation to the next, it is thought to have made leap-frogging improvements over the previous generation of fighter jets. Five generations of fighters are widely considered to have been produced, with the sixth well underway. However, it should also be noted that there can be a large spread within a generation without progressing to the next generation (which is why aircraft like the F-15EX are called a 4.5th generation fighter).

1 First-generation fighter jets

1st-gen fighter jets were built in the 1940s and 1950s

The first generation of fighter jets applies to the very first series of fighter jets to enter service. The two fighter jets to see combat in World War II were the German Messerschmitt Me 262 and Great Britain's Gloster Meteor (incredibly, two Meteors remain in service with Martin-Barker for testing ejection seats). The first generation also includes the United States Lockheed P-80 Shooting Star (later designated the F-80). The first models of the P-80 were sent to Europe just before Germany surrendered, but they didn't see any combat (the type would serve until 1997 as the T-33 Shooting Star trainer).

These jets had straight wings and basic avionics with no radars or self-protection countermeasures. They were armed with machine guns and unguided bombs and rockets (they were little more than WWII piston-engine fighters with a jet engine). These aircraft had a speed advantage over the piston engine fighters but were still subsonic. Apart from these first fighter jets, the opinion is divided on what jets to include in this category. Fighter World includes the F-86 Sabre, MiG-15, and MiG-17. However, this article follows the lead of Air and Space Forces Magazine and places these as second-generation aircraft.

2 Second-generation fighter jets

2nd-gen fighter jets were built in the 1950s and to early 1960s

The Korean War of 1950-53 was a major catalyst for fighter jet development. If the F-86 and MiG-15 are considered second-generation fighters, then a major characteristic of 2nd-gen was swept wings. Later second-generation fighters saw the introduction of the first air-to-air radars as well as infrared and semi-active guided missiles (however, air-to-air combat remained within visual range - although the new systems allowed aircraft to extend the range). They also had radar warning receivers. Engine design and improved aerodynamics led to these aircraft reaching and sustaining supersonic speeds in level flight.

Examples of second-generation fighter jets include the F-100 and MiG-19. The Lockheed F-104 Starfighter, Soviet MiG-21 Fishbed, French Dassault Mirage III, and British English Electric Lightning are often considered second generation (although some consider these to be third generation). The second generation saw the first development of interceptor-type aircraft while high speeds made guns unsuitable. Some of these jets remain in service with developing air forces around the world today - especially the MiG-21. In fact, the last MiG-21 (upgraded license-built Chinese Chengdu J-7 for the Bangladeshi Air Force) was built in 2013.

3 Third-generation fighter jets

3rd gen fighter jets were built from early 1960s to 1970

In the 1960s, fighter jets were developed with increased improvements in maneuverability and significant enhancements to their avionic suites and weapons systems. Early examples include the F-105, the F-106, and possibly the MiG-21. These jets featured advanced missiles, supersonic speeds, and more sophisticated engines. Aircraft started to be able to carry a wide range of weapons (including air-to-ground missiles and laser-guided bombs).

Some late third-generation fighter jets were among the first multirole fighter jets - including the MiG-23, F-4 Phantom II, and Mirage III. Some of these jets remain in use today (e.g., Turkey still operates the F-4 Phantom). Some improvements include the doppler radar supported with a 'lookdown/shoot-down' capability, along with semi-active guided radio frequency missiles like the AIM-7 Sparrow and AA-7 Apex. Aerial engagements with these later third-generation fighter jets moved beyond visual range. The early Hawker Siddeley Harrier may be thought of as third generation.

4 Fourth-generation fighter jets

4th gen fighter jets were produced from 1970s to present

The fourth generation of fighter jets span the longest period of time. These include the F-14, F-15, F/A-18, Su-27, MiG-29, Mirage 2000, and many more. Most fighter jets in use today are fourth-generation while the majority of new-build fighter jets are likely to still be fourth-generation. Notable improvements include head-up displays, fly-by-wire systems allowing for optimized aerodynamic designs, and improved avionics. These aircraft tend to be capable of multiple missions.

These aircraft have changed massively over the years, leading to the upgraded modern examples to be called 4.5th generation (aircraft that keep the old airframes and so lack stealth but have upgraded avionics). Examples of 4.5th generation aircraft include F/A-18 Super Hornets, F-16 Block 70, F-15 Strike Eagles, Eurofighter Typhoon, Rafales and possibly Russian jets like the Su-30 and Su-34, as well as the Chinese J-10C. 4.5th generation aircraft many incorporate some fifth-generation technologies like AESA radars, sensor fusion, Link-16 (or similar high-capacity digital network communications), reduced radar cross-sections, and more. In short, these aircraft are becoming aerial supercomputers while not being particularly stealthy.

5 Fifth-generation fighter jets

5th gen fighter jets were produced 2005 to present

Fifth-generation fighter jets are more stealthy flying supercomputers than traditional fighter jets. They are designed to have superior situational awareness and get the first shot in any engagement. Fifth-generation aircraft can be thought of as influenced by the idea that "you can't run, but you can hide." For example, the F-35 has been slowed to Mach 1.6 partly to prevent the heat friction from heating the aircraft and reducing its stealth.

These aircraft include multi-spectral sensors located across all aspects of the aircraft, allowing the pilot to have a 360-degree picture. These aircraft are mostly defined by their own board computers, software, and sensors (this makes comparisons difficult as most of this information is classified). It is generally not particularly meaningful to compare traditional specs (like speed) with 5th-gen fighters, as that is not what they are optimized for. Today's fifth-generation fighter jets are the F-22 Raptor, F-35 Lightning II, and Chengdu J-20. Lower-end fifth-generation fighters include the prototype Chinese J-35A and (according to Rusi's Professor Justin Bronks) the Russian Su-57 Felon.

6 Sixth-generation fighter jets

Sixth-gen fighters may be in service from 2030

Sixth-generation fighter jets are designed to be a "system of systems" and be something of a flying command center controlling loyal wingman drones and having an incredibly high situational awareness. European countries are skipping developing their own fifth-generation fighters and going straight to sixth-generation projects (Tempest/GCAP being the best example). These jets are planned to feature laser weapons, stealth technology, supersensor fusion, AI technology, and more. They are expected to be produced in low numbers.

The United States became the first to test fly a sixth-generation fighter jet in 2020 (it is believed Northrop Grumman, Lockheed, and Boeing have all built flying prototypes for the NGAD program). The UK's Tempest demonstrator is expected to fly in 2027, while China may have flown its first sixth-generation fighter in December 2024. Additionally, Northrop Grumman claims its Northrop Grumman B-21 Raider is the world's first sixth-generation combat aircraft. This is a classification normally applied to fighters and not bombers. It could be an indication of the multi-role capabilities of the new bomber.