The ship was grounded in 1931, due to the Depression, but was not dismantled for over 5 years. A pair of large airships, the Akron and Macon, that both functioned as flying aircraft carriers were procured by the US Navy. However, they were both destroyed in separate accidents. the Akron was flown into the sea in bad weather and broke up, resulting in the deaths of over seventy people, including one of the US Navy's proponents of airships, Rear Admiral William A. Moffett. Macon also ended up in the sea when it flew into heavy weather with unrepaired damage from an earlier incident, but the introduction of life-jackets following the loss of the Akron meant only two people died. LZ 129 Hindenburg carried passengers, mail and freight on regularly scheduled commercial services from Germany to North and South America. However, such services were brought to an abrupt end by the Hindenburg disaster of 1937. While the Hindenburg's sister ship, the LZ 130 Graf Zeppelin II, was completed, it would only perform thirty European test and government-sponsored flights before being grounded permanently. During 1938, Luftschiffbau Zeppelin was compelled to terminate Zeppelin manufacturing, while all operations of existing airships was ceased within two years. The frames of Graf Zeppelin and Graf Zeppelin II, along with scrap material from the Hindenburg, were subsequently scrapped that same year for their materials, which were used to fulfil wartime demands for fixed-wing military aircraft for the Luftwaffe. Demise Following the Hindenburg disaster, the Zeppelin company resolved to use helium in their future passenger airships. However, by this time, Europe was well on the path to the Second World War, and the United States, the only country with substantial helium reserves, refused to sell the necessary gas. Commercial international aviation was limited during the war, so development of new airships was halted. Although several companies, including Goodyear, proposed post-war commercial designs, these were largely to no avail. At an Air Ministry post-war planning session in 1943, a R.104 was proposed to fulfill the Air Ministry Specification C.18/43. Despite the presence of two airship stalwarts, Nevil Shute and Wing Commander T.R. Cave-Brown-Cave the airship was not adopted. The proposed R.104 was described by Lord Beaverbrook as "A pretty face, but no good in the kitchen." The decision was to develop the Bristol Brabazon to meet C.18/43. The Brabazon was a much ballyhooed failure of the post war period.