On Friday 14 March 2025, two elderly jet transports flew their last sortie for the Japan Air Self-Defense Force. The fitting detail was which two they were: serials 28-1001 and 28-1002, the very first Kawasaki C-1s ever built, the prototypes that had opened the programme more than half a century earlier. One wore a blazing phoenix livery with the words “C-1 Forever” on its side.

IL Kawasaki C-1 was Japan’s first home-grown jet transport, a compact, high-winged airlifter that looked like a scaled-down American Starlifter. Only 31 were built and none ever left Japan, yet for five decades it carried the Japan Air Self-Defense Force’s troops, paratroopers and cargo, and it spawned one of the oddest-looking aircraft in Japanese service.

Replacing a wartime veteran

By the mid-1960s, the JASDF’s transport fleet was built around the Curtiss C-46 Commando, a piston-engined Second World War design. Newer aircraft such as the C-130 Hercules had left it far behind, and rather than buy abroad, Japan decided to build its own replacement.

The job went in 1966 to the Nihon Aircraft Manufacturing Corporation (NAMC), the industry consortium that had just produced the YS-11 airliner. NAMC made Kawasaki the prime contractor, which is why the aircraft carries its name, while Mitsubishi built the middle and rear fuselage and other consortium members made the wings and control surfaces. It was one of the first aircraft programmes of postwar Japan.

Weapon Detective on the Kawasaki C-1 and its place in Japan’s aviation industry.

The prototype XC-1 first flew on 12 November 1970, production began the following year, and the type entered regular JASDF service in 1974. Two Pratt & Whitney JT8D turbofans, built under licence by Mitsubishi, hung under the high wing, and a rear ramp under the T-tail opened onto a pressurised hold.

Small, short-legged and very capable

The C-1 was designed for short, tactical hops. Leading-edge slats and four-stage Fowler flaps gave it strong short-field performance; Aviation Wire lists its shortest take-off run at 460 metres. The hold could take 60 fully equipped troops, 45 paratroopers or 36 stretchers, or vehicles loaded up the rear ramp, and its rear doors could be opened in flight to drop paratroopers and stores.

Its crew of five was generous by modern standards: two pilots, a flight engineer, a navigator and a loadmaster. Its successor, the C-2, needs only two pilots and a loadmaster. Top speed was about 806 km/h, faster than the turboprops it was often compared with.

The Okinawa problem

The C-1’s weakness was range. With its maximum payload of 11.9 tonnes it could fly only about 1,300 km, and AeroResource notes that the short reach was deliberate, keeping the aircraft within Japan’s borders in line with the defensive policy of the time.

Then, in 1972, the United States returned Okinawa to Japanese rule. From most of the home islands, the C-1 could not fly there directly with a worthwhile load. Combined with the defence budget cuts of the 1970s, that sealed its fate: orders were cut, and Japan turned to the C-130H Hercules instead. The last five C-1s delivered, designated C-1A, were given an extra 4,730-litre fuel tank to stretch their legs, but only 31 were ever built.

The programme mattered beyond the air force. Japan’s trade ministry, MITI, at one stage chose the C-1 design as the basis for a next-generation commercial transport, before dropping the idea to concentrate on international work such as Boeing’s 767. According to political scientist Richard J. Samuels, as summarised on Wikipedia, lessons in structural design and fatigue prevention from the C-1 flowed into Japanese car and railway manufacturing.

Its crews grew fond of it, and Iruma liked to show it off. When IrumaFor the 60th anniversary of the 2nd Tactical Airlift Group in 2018,rsquo;s 2nd Tactical Airlift unit marked its 60th anniversary in 2018, C-1 78-1026 was painted in a striking red and white scheme nicknamed “Kabuki”, AeroResource recorded, before returning to standard camouflage in early 2019.

A Kawasaki C-1 flying display at the Iruma air show in 2012.

The Platypus and the Asuka

The C-1 airframe was adapted for some unusual jobs. In 1983 and 1984 Kawasaki converted the 21st aircraft, 78-1021, into the EC-1 electronic warfare training aircraft. Its bulbous nose radome and bulging fairings earned it the nickname “Platypus”, a name later passed on to its successor, the EC-2 based on the C-2.

Stranger still was the Asuka, a quiet short take-off and landing research aircraft built for Japan’s National Aerospace Laboratory on a C-1 airframe. It had four FRJ710 turbofans mounted on top of the wing to blow air over the flaps, and between 1985 and 1989 it made 97 test flights. It is now preserved at the Gifu-Kakamigahara Air and Space Museum.

Fifty years at Iruma

The C-1 served with three squadrons over the years. As the larger Kawasaki C-2, first flown in 2010 and able to lift about three times the payload, came into service, the remaining C-1s were concentrated with the 402nd Tactical Airlift Squadron at Iruma Air Base near Tokyo in April 2018.

The C-1’s record was not spotless: four were lost in accidents over five decades, two of them together in a formation crash in 1983. But the type kept flying long after most of its contemporaries had gone. The JASDF gave prototype 28-1002 its phoenix paint scheme in early 2025, the EC-1 retired on 13 March, and the following day the last two C-1s made their farewell flights.

According to The Unit Report, one more C-1, 08-1030, had flown from Iruma to Hamamatsu, home of the JASDF museum, two days before the end. A small, short-legged transport that was never sold abroad had served its country for more than 50 years.

C-1s 030 and 002, the second prototype, departing Iruma Air Base one after the other.

The C-1 was never going to win a range contest, but that was never its job. It proved that postwar Japan could design and build its own military jets, and it handed its role, its crews and even its nickname-worthy EW mission straight on to the next Kawasaki airlifter.

Sources: Wikipedia (Kawasaki C-1; 402nd Tactical Airlift Squadron), AeroResource (JASDF Iruma operational report, 2019), Aviation Wire (January and February 2025), The Unit Report (14 March 2025), Ukraine State Aviation Museum