F 4 Frösön

F 4 Frösön, Kungliga Jämtlands Flygflottilj, Royal Jämtland Air Force Wing, or simply "F 4", is a former Swedish Air Force wing with the main base located at Åre Östersund Airport outside Östersund on Frösön in the middle of Sweden.

History of the airbase
The airbase was set up in 1926 as the 4th Flying Corps at the old base of Jämtland Field Ranger Regiment at Frösö läger (Frösö camp). The main task was to perform reconnaissance for army units.

In 1930, the duties were extended to bombing with B 4 and later B 5 planes.

In 1936 the Flying Corps was reorganized as an own branch (the Air Force) and the unit was renamed Jämtlands Flygflottilj (Jämtland Air Force Wing).

In 1947, the wing was yet again redesigned as a fighter wing and received surplus P-51 Mustangs designated as J 26. These were only kept for five years until they were replaced by J 28A jets in 1952. Again, after only four years, they were in turn replaced by J 29A in 1956.

In 1967 the J 32B entered service at the wing only to be replaced again in 1969 by J 35D. These served until 1984 when the Saab 37 Viggen was introduced as served the wing for 20 years.

The JAS 39 Gripen served briefly for only a year as a replacement for the Viggens until the wing was decommissioned in 2005. The airfield is known today as Åre Östersund Airport.