Taiwan's F-CK-1 Ching Kuo fourth generation fighter first entered service in 1997, and today serves in the Air Force alongside the Mirage 2000, F-16A and heavily modernised variants of the F-5. While formidable, the Ching Kuo has alongside other fighter's in Taiwan's Air Force increasingly found itself outmatched by more sophisticated Chinese platforms such as the J-10 light fighter and the elite heavier J-11, Su-30 and Su-35. China's induction of its first fifth generation fighter in 2017, the J-20 heavy platform, further increased the already large technological disparity strongly favouring Beijing, and China's Air Force plans to induct more 4++ and fifth generation fighters in future such as the J-11D and J-31.&nbsp; In an attempt to reduce its capability disadvantage Taipei has initiated an extensive domestic modernisation program for its Ching Kuo fighters to allow them to better contend with their modern Chinese analogues. Taiwan's Aerospace Industrial Development Corporation was tasked with upgrading the fighters under a program known as Hsiang Zhan, which was initiated in two phases. Phase One was carried out from 2009 to 2014 and involved 71 fighters from the Air Force's 443rd Tactical Fighter Wing. Phase Two was then initiated to upgrade 56 more fighters from the 427th Tactical Fighter Wing. Under the Hsiang Zhan upgrade program fighters' radars, avionics, engines and weapons systems were all extensively modernised. Three colour head up displays (HUD), new 32 bit flight control computers, Golden Dragon CD-53 multi mode pulse doppler radars and glass cockpits were all integrated onto the Ching Kuo's airframe. The fighters were also modified to launch advanced indigenously developed air to air missiles, including the Wan Jian (Ten Thousand Swords) stand off missile and the Tian Jian II (Sky Sword 2) long range air to air missile - a platform capable of striking targets at ranges of up to 100km. The Air Force also indicated a potentially offensive role for the fighters, stating that future fighters were set to be equipped with anti radiation systems invaluable for operations to suppress enemy air defences. Unlike the U.S. made F-16 and French Mirage 2000, the Ching Kuo's indigenous development allows the Taiwanese military to modernise the platform domestically at a far lower cost. This is particularly significant considering the great expense Taiwan's military undertook to send F-16A fighters to the United States for similar upgrades. While upgrades to older and lighter fighters cannot bridge the gap with China's own Air Force, which is itself modernising its capabilities rapidly, it is critical to preventing Taiwan's Air Force from falling into complete obsolescence in a potential Taiwan straits conflict.