By most definitions, a Gen-5 aircraft has all the capabilities of a Gen-4/4.5, plus all-aspect stealth (even when armed), Low Probability of Intercept Radar (LPIR), a high-performance airframe, advanced avionics, and highly integrated computer systems able to network with all other U.S. (and, where possible, allied) aircraft, satellites, and ground systems within the battlespace to provide the pilot with a significant advantage in situational awareness.

Added to that, with the F-22, was supercruise – the ability to maintain supersonic flight for long distances and without afterburners. The F-22 was far from the first to have supercruise, however. That honor goes to the British-built English Electric (now BAE Systems) Lightning – in 1954. The British Aircraft Corporation (BAC) Tactical Strike/Reconnaissance 2 (TSR-2 – first flight September 1964) and the Soviet Tupolev Tu-144 Charger transport aircraft (1969) were among the first specifically designed to cruise supersonically.

But the all-time record-holder for supercruise – with more supersonic flight hours than all others combined – was the Aérospatiale-BAC Concorde, a commercial jetliner that flew mostly transatlantic routes for 27 years before being retired in 2003.

With only two Gen-5 aircraft in the world’s military air fleets – one now out of production, the other yet to begin full-scale production and with an initial operational capability (IOC) target ranging from 2014 to 2018 (depending on variant) – talk of a Gen-6 aircraft might seem somewhat premature. However, given that preliminary work on the F-22 began in the mid-1970s and on the F-35 in the mid-’90s, concept and initial design studies on a Gen-6 aircraft begun in early 2012 probably would not lead to a production aircraft until the mid- to late 2030s – providing it became an actual budget-item program with adequate funding for research, development, test, and evaluation.

While some question the need for even a Gen-5 fighter, if no potential adversary is likely to field one anytime soon, discussions of a Gen-6 are extremely preliminary. Nonetheless, the U.S. Air Force already has begun asking industry for ideas – largely because USAF air fleet projections show a shortfall of nearly 1,000 fighters by 2030, even if all F-35s are delivered on schedule and the F-22 continues to fly. The shortage will come from the retirement of most, if not all, legacy aircraft currently in the fleet – including those few still in limited production – most of which the F-22 and F-35 are intended to replace, but in far fewer numbers.

The problem could be far worse if Russia or China do succeed in building a Gen-5 fighter and produce them in large numbers, something both have claimed they will do, although economic problems in both nations may slow or seriously reduce those plans. While Europe, in a joint program, has or could develop the technologies required for a Gen-5 aircraft, current economic problems in the European Union – combined with significant planned defense budget cuts – make that unlikely.

In November 2010, the USAF issued a “capability request for information (CRFI)” to industry to assist an Aeronautical Systems Center look at “applicable materiel concepts and related technology for a Next Generation Tactical Aircraft (Next Gen TACAIR) capability with an initial operational capability (IOC) of approximately 2030. The envisioned system may possess enhanced capabilities in areas such as reach, persistence, survivability, net-centricity, situational awareness, human-system integration and weapons effects. It must be able to operate in the anti-access/area-denial environment that will exist in the 2030-2050 timeframe.”

A few months later, DoD issued a 30-year Aircraft Procurement Plan for the Navy and Air Force. That included a Gen-6 fighter – possibly unmanned – for the Navy, designated the Next Generation Air Dominance aircraft, as a possible Super Hornet replacement. However, it made no mention of such an aircraft for the Air Force to replace either the F-22 or the F-35A, although it did include a new long-range, nuclear-capable bomber for either manned or unmanned missions.

While then-Defense Secretary Robert M. Gates said the plan should not be seen as a blueprint for future DoD programs, it and the USAF CRFI were the most official statements to date on plans for Gen-6 aircraft. What remained unanswered was how Gen-6 would build upon – and differ from – Gen-5.

The F-35 was created as a U.S. tri-service and international aircraft in part to make it more affordable and to give all three aviation services and primary allies equivalent and fully interoperable combat and networking capabilities. One question regarding a Gen-6, then, would be whether it would follow the F-35 model or that of the F-22, which was built and is operated exclusively for and by the U.S. Air Force, with international sales forbidden by Congress.