After its launch in October 2021, the world’s first 2-seater stealth fighter is said to be entering service with the Chinese Air Force in the near future.
The name of the aircraft is expected to be J-20S or J-20AS. It seems that J-20AS will be the official designation of this fighter, as it is based on the J-20A’s airframe.
The difference between the J-20AS and its predecessor is the indigenous WS-10C engines instead of the Russian AL-31FM2. The new engines are expected to offer greater reliability and a supercruise capability, as well as reductions to the aircraft’s radar cross section and various improvements to avionics. The twin seat variant not expected to be primarily used as a trainer, but rather to accommodate weapons systems officers for roles such as drone control, command and control and operation of air to ground weapons.

While the J-20’s direct American analogue the F-22 was initially planned to be developed into a twin seat variant, with F-22B prototypes ordered and a bomber fighter variant also considered as the FB-22, these programs were cancelled. Production of the fighter was then prematurely terminated in 2011 as a result of its extremely high maintenance needs and operational costs as well as wide ranging performance issues.
Where the U.S. was unable to develop the F-22 further, ambitious plans for the J-20 are already taking the design well ahead of its rivals including development of both strike and electronic attack derivatives which will likely use the twin seater as a basis for development. The J-20 is currently being produced at a far greater rate than any twin engine fifth generation fighter ever has, and likely ever will, with the cancelled F-22 and low production rate Su-57 both falling far behind leaving the F-35 as its only near peer level competitor.

The F-35 and J-20 are the only aircraft in the world currently in production and service at the squadron level. The F-35’s smaller size has made development of a twin seater unfeasible, however, and unlike the J-20 ongoing performance issues have prevented it from being approved for full scale production.
Despite the greater cost and slightly reduced kinematic performance, there are undoubtedly several operational roles a two-seat J-20 could perform better – most obviously those involving operations of long-range sensors and employing guided air-to-surface weapons. Similarly, the aircraft’s expanded capacity as a command-and-control hub could particularly apply to drone control.

The development of a flying J-20AS shows China can afford to develop specialized stealth fighter. For now, Chinese aviation observers must await further evidence to gain a clearer picture as to plans to employ its unique two-seat stealth fighters.