 Rfa 501 later moved its base to Scheldewindeke airdrome south of group headquarters at Gontrode, while Rfa 500 was based at Castinne, France, with its primary targets French airfields and ports.Rfa 501, with an average of five R.VI's available for missions, conducted 11 raids on Great Britain between September 28, 1917, and May 20, 1918, dropping of bombs in 30 sorties.Aircraft flew individually to their targets on moonlit nights, requesting directional bearings by radio after takeoff, then using the River Thames as a navigational landmark.