Aircraft 001, the first serial-production KF-21 Boramae, now belongs to the Republic of Korea Air Force. Maj. Han Jae-seok flew it from Korea Aerospace Industries’ plant at Sacheon to Yecheon Air Base in North Gyeongsang Province on Sept. 22, 2026, completing the handover of the first fighter South Korea has developed at home. The service plans a fleet of 40 Block I jets by 2028.
The delivery closes a development run that began on paper in March 2001. The jet now moves from test program to squadron service, with a Block II version already planned to follow.
The Aviationist’s report on the delivery, published Sept. 23, 2026, puts the milestone plainly: “the KF-21 is South Korea’s first domestically developed fighter aircraft.” It says the first aircraft arrived “25 years and six months after then-President Kim Dae-jung announced a domestic fighter aircraft program in March 2001,” and that “the ROKAF is looking at a fleet of 40 KF-21 Block I jets, to be delivered by 2028,” followed by 80 Block IIs by 2032.
Aircraft 001 rolled out of the factory on March 25, 2026, and was delivered after acceptance trials, according to the same report. On the delivery flight it was escorted by three jets: an FA-50 light attack aircraft, a TA-50 fighter trainer and a T-50 jet trainer.
A reactivated Phantom squadron at Yecheon
The new fighters go to the 156th Fighter Squadron under the 16th Fighter Wing. The Aviationist reports that the squadron, a former F-4E Phantom II unit disbanded in 2012, was reactivated on June 1, 2026, as a KF-21 unit. The Seoul Economic Daily reported on Sept. 22, 2026 that Han signed the acceptance document as the first KF-21 pilot, and that the Air Force plans to declare the type operational in the second half of 2027.
Han spoke at the end of the delivery flight. Asian Military Review, in its Sept. 22, 2026 report on the handover, quoted him:
“Now that the ROKAF has taken delivery of the KF-21, which was perfected through the efforts of countless people, we will carry on this immense responsibility to steadfastly defend the Republic of Korea’s airspace.”
The same outlet reported the 40 Block I aircraft are scheduled in two halves, 20 by 2027 and the remaining 20 by 2028, with initial operational capability targeted for the second half of 2027.
From 2015 development start to combat certification
Full-scale development began in December 2015. A prototype was unveiled in April 2021 and first flew in July 2022, and six pre-production prototypes logged “more than 2,000 hours of test sorties through 2025,” per The Aviationist. The Elec, a Korean trade outlet, noted in its Sept. 23, 2026 delivery report that the handover came about 10 years and nine months after development began, and listed the fighter’s top speed as Mach 1.8, about 2,200 kilometers per hour, with a maximum takeoff weight of 25.6 tons.
The final gate before production deliveries was combat certification. South Korea’s Defense Acquisition Program Administration (DAPA) announced in May 2026 that the KF-21 had been certified combat suitable, according to the government portal Korea.net, in a May 8, 2026 report. Flight performance, aerial refueling and weapon firing “were confirmed through an estimated 1,600 flight tests and some 13,000 flight condition evaluations,” Korea.net reported. The jet had been rated “provisionally combat suitable” in May 2023.
Noh Jiman, director general of DAPA’s KF-21 Program Group, said at the time:
“This symbolic result demonstrates the Republic of Korea’s fully autonomous capacity to develop fighter jets.”
Block II and beyond
The Block I is the starting point, not the finished design. The Aviationist reports that Block II aircraft will add enhanced air-to-ground capability, and that a later Block III would move toward fifth-generation features: low-observable coatings, internal weapons bays and indigenous KTF16000 engines, with a first flight expected around 2040. Those are plans, not tested hardware.
The production contract is already on the books. KAI received a contract worth 1.9 trillion won for the first 20 Block I jets, according to The Aviationist. The Seoul Economic Daily reported the Air Force intends to field more than 100 KF-21s by the early 2030s.
The next verified marks on the schedule are the operational declaration in the second half of 2027 and the 40th Block I delivery by 2028.
Top image: KF-21 Boramae prototype 006 in flight. The first production jet is not shown. Image Credit: Republic of Korea Ministry of National Defense — KOGL Type 1 / Wikimedia Commons
This article was produced with the assistance of AI and reviewed by Combat Rated editors prior to publication.