The J-20 was supposedly designed with a faceted, turret-mounted infrared-search and track (IRST) system—a critical sensor found on all Russian-built fighters that will allow the J-20 to better survive in a high-threat air combat environment even against America's advanced stealth fighters (read all about IRSTs in this past feature of mine). Known as EORD-31, the J-20's IRST lifts upwards out of its nose in front of the windscreen when in use.

The large, diamond-like aperture for this system is clearly seen in photos of the jet, but its development could be delayed. In its place, Chengdu Aircraft Corporation engineers could have mounted a fixed IRST sensor in the stealthy ventral enclosure below the aircraft's nose. This would allow for the J-20 to maintain a constant radar signature while using its IRST.

Alternatively, and more likely, the sensor inside the under-nose enclosure could be the other planned primary optical sensor for the J-20 that would work with the aircraft's IRST, radar, end electronic support measures, and other combat systems. Dubbed the EOTS-86, this sensor surely operates at shorter wavelengths than an IRST and allows for long-range visual identification of potential threats.

Used in conjunction with the IRST, it would allow the J-20 to silently detect and engage targets at beyond visual ranges—with the IRST detecting and the EOTS-86 identifying targets—even while operating under the most restrictive rules of engagement and without emitting any electromagnetic energy that can be detected by opposing forces. Even without the help of the IRST, the EOTS-86 would be able to be slaved to the J-20's radar and could provide visual tracking and identification of targets in a way in which its radar cannot.

America's F-15C/Ds are employing Sniper targeting pods in a very similar fashion and are slated to receive an advanced long wave-length IRST sensor as well. The Super Hornet will also feature a similar mix of capabilities and the F-35's EOTS does long-range airborne visual identification as a secondary function, but the jet lacks a traditional IRST entirely.

But once again, this sensor cannot be used to the extent of the F-35's EOTS. It would be used for target identification and possibly targeting from the frontal hemisphere only, not from steep angles below or even behind the aircraft as traditional targeting pods are capable of. It probably doesn't have a laser designator either. But just as a situational awareness tool alone, and a passive one at that, it represents a potent capability even the F-22 doesn't possess.

It's also possible that a true multi-role sensor similar to the F-35's EOTS and its wide-field of view faceted sapphire glass enclosure will find its way on the J-20 sometime in the future as its mission set expands and as China's sensor know-how improves. But that simply doesn't exist at this time.