 On their return to Martlesham , Dowding outlined his concerns about night interceptions and the characteristics of a proper night fighter . Since the interceptions were long affairs , the aircraft needed to have long endurance . To ensure that friendly fire was not an issue , pilots would be required to identify all targets visually . This meant a separate radar operator would be needed , so the pilot would not lose his night vision by looking at the CRTs . And finally , since the time needed to arrange an interception was so long , the aircraft required armament that could guarantee destruction of a bomber in a single pass — there was little chance a second interception could be arranged . 
