No. 1 Fighter Sector (1FS) was a Royal Australian Air Force (RAAF) unit formed at Bankstown, New South Wales on 25 February 1942. The RAAF commandeered Capitol Theatre at Bankstown for use as an operations and plotting facility on 14 March 1942. No. 1 Fighter Sector handed over operations to United States Army Air Corps (USAAC) on 10 April 1942. The operations shifted to a disused railway tunnel at St James railway station in Sydney. ADHQ was disbanded on 27 January 1947.