South Korea to Retire F-5s Early Due to KF-21 Success

The South Korean Air Force announced that, with the KF-21 program progressing better than expected, it will retire the remaining fleet of aging KF-5E/F Jegonghos in 2027. This is three years earlier than originally planned.

The Korea Herald reported on this.

“We are moving quickly to retire the F-5,” said Air Force Chief of Staff Gen. Son Seok-rak during a press conference at Seongnam Air Base.

The F-5 is an American light fighter developed by Northrop. South Korea first purchased the F-5A/B in 1965 and, later, in the 1970s, received the F-5E variants. Since 1982, localized production of the F-5E and F-5F has been established in South Korea under the designations KF-5E and KF-5F.

Currently, 48 KF-5E/Fs remain in service, concentrated at Suwon/K-13 Air Base, where they are operated by the 101st, 105th, and 201st Fighter Squadrons.

Son Seok-rak’s statements came amid the approaching operational deployment of the KF-21, a 4.5-generation fighter jet developed by Korea Aerospace Industries (KAI).

Earlier in the day, KAI CEO Kim Jong-chul said that the first production KF-21, unveiled on March 25, has already made its maiden flight and is currently undergoing test flights before being handed over to the Air Force in early September.

According to KAI, over 13,000 test conditions have been performed during the development of the KF-21 and about 1,600 flights have been made without accidents. The company expects to produce over 20 KF-21s per year thanks to automated production processes.

The company’s CEO also said that they see potential demand for over 200 KF-21s abroad. Negotiations are ongoing with countries including Indonesia, Malaysia, the Philippines and Poland.

As AeroTime notes, the program is progressing but faces challenges. The cost of the second phase of production, known as Block-II, is already estimated at $12.5 billion, almost 30% higher than the initial 2024 estimate of $10.5 billion.

South Korea’s Defense Acquisition Program Administration explained the increase in cost by inflation, the weakening of the Korean currency and global disruptions in supply chains.

The KF-21 program was launched in 2015 with the aim of replacing South Korea’s aging F-4 and F-5 fleets. The first prototype was presented in 2021. The initial Block-I phase plans to produce 40 aircraft focused on air combat by 2028.

Block-II involves the supply of another 80 fighters, which will already acquire full-fledged multi-role capabilities by 2032.

However, rising costs could push those timelines back. Officials are reportedly considering delaying the delivery of the first 40 aircraft by one year to 2029, while the second batch could enter service two to three years later than originally planned.