 After the fighters had reached the combat zone, pilots tried to identify and intercept enemy bombers visually; searchlights were to be used to illuminate the sky.Initial tests using former flying instructors experienced in blind-flying techniques, suggested the ideal weather conditions were when a certain (not too thick) lower level cloud cover prevailed, since then the bomber would be silhouetted against the back-lit clouds and the high-flying German fighters could easily spot their targets.During trials, ceasefires with the German flak units were arranged, to prevent friendly fire but it became apparent that co-ordination of ceasefires with "Wilde Sau" operations was difficult.