General aviation was prohibited during the war except for the Civil Air Patrol. Many private aircraft owners volunteered their aircraft and their services to patrol the coast for submarines. If one was spotted, they would report it to the Navy. I had an old friend that flew his Fairchild 24 off the coast of North Carolina until one day his engine quit at sea and he was later picked up by a boat. After the war, one of the German sub commanders responded that it was those "pesky little yellow airplanes' that worried him the most as they could rarely be seen or heard.