No. 20 Squadron was formed at Port Moresby , New Guinea , on 1 August 1941 for a general reconnaissance role , under the command of Squadron Leader W.N. Gibson . Its establishment was six PBY Catalina flying boats and 133 personnel , but only five aircraft ( all transferred from No. 11 Squadron ) and 55 personnel were available initially . The squadron conducted long @-@ range patrols between bases scattered around the islands to Australia 's north in conjunction with No. 11 Squadron . On 18 November , No. 20 Squadron 's Catalinas were augmented by two Short Empire flying boats transferred from No. 11 Squadron .