The KF-21 Boramae, a Korean fighter jet, overcame the U.S. government’s refusal to transfer technology and started flying with an active electronically scanned array (AESA) radar of Korea’s own development. AESA radar is like the eye of fighter jets. According to Hanwha Systems on March 6, the KF-21 Korean fighter started flight tests for performance verification by loading the AESA radar into a prototype of the KF-21. The AESA radar is key avionics equipment for the KF-21. It electronically steers radar beams by mounting about 1,000 small transmit/receive modules on the fighter’s antenna and adjusting the phase of the radio waves. From February 2023 to February 2026, the KF-21 will undergo development and operation test evaluations such as maximum detection and tracking distance in air-to-air mode and tracking accuracy through flight tests. Initially, South Korea tried to receive AESA radar technology from the U.S. F-35A, but the United States refused. However, after turning to its own development, South Korea developed both the hardware and software. It was then mounted on the KF-21 prototype and tested and evaluated. In 2021, Hanwha Systems conducted a flight test by installing the AESA radar on a test aircraft remodeled from a civil aircraft in South Africa with the Agency for Defense Development (ADD) and verified its performance through flight tests in Korea from November 2022 to February 2023. This process improved the quality of the AESA radar’s several operating modes and significantly boosted its reliability.