On 29 July 2026, at Korea Aerospace Industries' plant in Sacheon, South Korea did something only a handful of nations have ever managed: it declared its own supersonic fighter finished. The KF-21 Boramae — "young hawk" — is officially through development, a decade after the program began.

Here is the number that should make every other fighter program jealous: across roughly 1,600 test sorties over about 42 months, the KF-21 did not suffer a single accident. Not one lost jet, not one write-off. For a clean-sheet fighter, that is almost unheard of.

With the milestone, Seoul says it becomes the eighth country to independently develop an advanced 4.5-generation-or-better supersonic fighter. Next stop: the factory floor.

Ten years from drawing board to done

Systems development formally kicked off in December 2015. The ceremony marking its completion drew about 300 people to Sacheon, roughly 185 miles southeast of Seoul — among them the head of the Defense Acquisition Program Administration (DAPA), representatives of some 500 South Korean suppliers, and officials from Indonesia, the program's international partner.

The first mass-production KF-21 is scheduled to reach the Republic of Korea Air Force around September. DAPA plans to field 40 jets — optimised first for air-to-air combat — by 2028, then another 80 with expanded air-to-ground capability by 2032, for a planned fleet of 120.

1,600 flights, zero crashes

A flawless flight-test record is the kind of thing engineers frame and hang on the wall. It reflects a conservative, methodical program — and it gives export customers a powerful selling point when the competition includes jets with far messier development histories.

What it is — and what it isn't yet

The KF-21 is a twin-engine, canted-tail fighter that looks, at a glance, like a slightly smaller cousin of the F-22 and F-35. It is powered by a pair of General Electric F414 engines. But it is not a full fifth-generation stealth aircraft — at least not yet. Early jets carry their weapons externally rather than in an internal bay, so it sits in the 4.5-generation bracket, with a stealthier, internally-armed evolution planned down the line.

That is the point of the Boramae: a capable, affordable, largely home-built fighter that South Korea controls end to end, rather than importing off the shelf.

From a standing start in 2015 to a finished fighter in 2026, with a spotless safety record and a production line spinning up — that is a serious industrial achievement, and a warning shot to every established fighter exporter. The young hawk has left the nest.

Sources: UPI; Seoul Economic Daily; Korea JoongAng Daily; The Aviationist; Defence Security Asia.