Iruma was established in 1937 by the Imperial Japanese Army Air Force and named Irumagawa Airfield. Opened in December 1938, it was the air academy for the Japanese Army Air Force, with its academy located at the nearby town. Mostly training aircraft operated from the base, including Kawasaki Ki-10 biplanes painted orange. During World War II, the IJAAF 14th Sentai operated Mitsubishi Ki-67 medium bombers from Irumagawa. Attacked several times by USAAF B-29 Superfortress bombers, the last missions by the IJAAF were one-way missions using Yokosuka MXY7 Ohka purpose-built, rocket-powered, human-guided, anti-shipping kamikaze attack planes against American ships operating off the coast.
American use
After the end of the war, the United States Army Air ForcesFifth Air Force headquarters on Okinawa was moved to Japan and was established at Irumagawa on 25 September 1945. The base was renamed Johnson Air Base in honor of Lieutenant Colonel Gerald R. Johnson, the former commander of the USAAF 49th Fighter Group. A little over a month after the war ended, Lt. Col. Johnson was piloting a B-25 Mitchell, which had been pressed into service as a transport aircraft. He flew into a typhoon and was hopelessly lost in the black skies. He ordered everyone to bail out, but one person neglected to bring a parachute. Johnson immediately gave his parachute away and tried to fly the B-25 back safely. Johnson's copilot also elected to stay behind to help Johnson, but both were killed when the B-25 crashed on approach to Irumagawa. Johnson Air Base was a major United States Air Force base in Japan during the occupation years, then later during the Korean War and the 1950s. USAF Far East Air Force command units based at Johnson were:
In August 1958, the JASDF Central Air Defense Force headquarters and Iruma Air Base were established at Johnson Air Base. On 30 December 1960, the American facilities on the site of Johnson Air Base were re-designated as "Johnson Air Station". In June 1961, Japan-US joint use agreement was established at Johnson. In June 1962, the USAF ended its use of the air base, when the 41st Air Division headquarters moved to Yokota AB. On 1 January 1963, the buildings of the air station were re-purposed for American family housing in Japan as "Johnson Family Housing Annex". The USAF 6102d Air Base Squadron became the host unit at Johnson, supporting the 6022d USAF Hospital and family housing civil engineering flights. In November 1963, the base transitioned from USAF management to the JASDF. On 28 June 1973, the USAF support units were inactivated, and most of their associated facilities were transferred back to the Japan Air Self-Defense Force. The major facilities retained by USAF at Johnson were the telecommunications center, telephone exchange, admin office, Aircom MW relay, electrical power stations, and HF antennas. These facilities were transferred to the control of the 475th Air Base Wing at Yokota AB and continuously operated by the AFCS 1956th Communications Group until MW tower relocated to the USAF Tokorozawa Transmitter Site, approximately southeast from Johnson. In September 1978, the last USAF facilities were closed and completely returned to the Government of Japan.
Iruma Air Show
The Iruma Air Show is held annually on the November 3rd Culture Day. It generally takes place under clear blue skies. The event features ground displays of various military aircraft from all three branches of the Japan Self-Defense Forces and a performance by Blue Impulse, the JASDF's aerobatics team. Police department helicopters are also usually on ground display. In recent years UH-1N and C-12J aircraft of the US Air Force's 459th Airlift Squadron also visit from the nearby Yokota Air Base. A speaker at the 2010 air show sparked controversy when he criticized the government. Due to the base's proximity to Tokyo a large number of spectators attend the event each year, although numbers can fluctuate. In 2015 the attendance was approximately 200,000, in 2016 it was 130,000 and in 2017 around 210,000 people came to the event.
Tenant squadrons
As of 2017, the following units are based at Iruma:
