The Type 90 twin-35mm anti-aircraft artillery (AAA) is a Chinese copy of the Swiss Oerlikon GDF, one of the world’s most capable low-altitude air defence weapon systems. The weapon was designed to engage high-speed, low-flying aircraft, helicopters, unmanned aerial vehicles (UAV) and cruise missiles. A tracked self-propelled variant of this weapon has also been produced and tested but it did not enter the PLA service. The Type 90 replaced the obsolete Type 65 and type 74 twin-37mm AAA to provide field air defence for the ground forces at the division and group army level.

China imported a small number of the Oerlikon GDF twin-35mm AAA and the associated Skyguard air defence radar system from Switzerland in the 1980s. Later the weapon was produced in China locally under license as the Type 90. The Oerlikon GDF AAA system is available in three major variants: GDF-1, GDF-2 and GDF-3. It is not known exactly which model the Type 90 was based on, but it is thought to be comparable in performance to the GDF-2 developed in 1980. The Type 90 was first revealed to the public during the 1999 National Day parade held in Beijing.

Comparing to the PLA’s obsolete manually-operated twin-37mm AAA, which were based on the 1950s-era Soviet designs, the Type 90 is much more advanced in terms of technology and capability. Once set up, the AAA system can be operated by one person. The autoloader make it possible to feed and fire all the ammunition available on the gun without manual intervention. The system’s reaction time to an airborne target is only 6 seconds, and the whole system can be set up or retreated within 90 seconds.

The Type 90 includes a computer controlled electro-optical director for 3-dimensional target tracking in conjunction with the laser range finder. The Type 902 (Chinese copy of the Skyguard) millimetre-wave target searching radar has a detection range of 8,000m. The AAA system can work either in conjunction with the Type 902 fire control radar or autonomously. A typical battery using the Skyguard radar consists of two twin 35 mm gun platforms with a single fire control radar. In addition, the 35mm guns are also highly lethal against ground targets.

The 35mm cannon mounted on a 4-wheel cartridge has a cyclic rate of fire of 550 rounds/min. The muzzle velocity is 1,175m/s. The cannon fires high explosive incendiary rounds. It is not clear whether China has also obtained the Advanced Hit Efficiency and Destruction (AHEAD) round technology from Switzerland along with the Oerlikon 35mm gun. The AAA system carries 280 rounds for each barrel. The reloading time is 7.5 seconds. The iconic large muzzle break is missing on the later variant of the Type 90.

The fire-control unit used by the Type 90 was based on the improved Skyguard-II, which differs from the basic variant Skyguard in that it has two tracking systems—a Type 902 target searching radar and an electro-optical passive tracking director. The electro-optical tracking system uses high-resolution optical/infrared TV for passive tracking in clear weather. The advantage of continuing tracking without emitting radar signals increases its survivability when facing enemy anti-radiation missiles (ARMs).