Swales' first operational flight for 582 Squadron was on 12 July 1944. Newly promoted to captain on 4 November 1944, he took part in a daring daylight bombing raid on 23 December, on the Gremberg railway yards, Cologne, Germany. The Squadron Leader for the raid on Cologne was his close friend, Robert Palmer, D.F.C., who normally flew Mosquitos with 109 Squadron, also based at Little Staughton. Swales was the number two Pathfinder, leading the main flight and following Palmer as he marked the target. Palmer, who had completed 110 bombing raids, was killed as his Lancaster was damaged by German fighter and crashed. Six of the 30 aircraft on this operation were lost.