The 1956 Atlantic R6D-1 disappearance involved a Douglas R6D-1 Liftmaster (BuNo 131588) of the United States Navy which disappeared over the Atlantic Ocean on 10 October 1956 with the loss of all 59 people on board. At the time, it was both the second-worst air incident to have occurred over the Atlantic and the second-deadliest involving any variant of the Douglas DC-6.