The Convair F2Y Sea Dart was a supersonic seaplane jet fighter that had skis rather than wheels. In the late 1940s, the United States Navy feared that supersonic aircraft would stall at low speeds required for a carrier arresting gear, and therefore would not be able to land on a conventional aircraft carrier. The Sea Dart would land on (smooth) water; then be lowered and raised from the sea via crane. The Navy also considered combining the Sea Dart with the unorthodox approach of a submarine aircraft carrier that could carry up to three such aircraft inside purpose-built pressure chambers. They would have been raised by a portside elevator aft of the sail and either take off on their own from a smooth sea or be catapult launched from the aft in a higher sea. During the test flight phase, the hydro-skis generated violent vibrations during takeoff and landing, while a fatal crash caused by structural failure also marred the programme; the Navy opted to cancel all production aircraft.