PBY Catalina was the United States' Navy designation for an American and Canadian-built flying boat of the 1930s and 1940s. PB stands for Patrol Bomber, with Y being Consolidated Aircraft's manufacturer identification. It could be equipped with depth charges, bombs, torpedoes and .50 caliber machine guns and was one of the most widely used multirole aircraft of WWII. Catalinas served with every branch of the US military and in the air forces and navies of many other nations. In the United States Army Air Force, their designation was the OA-10, while Canadian-built PBY's were known by the nickname Canso.