The 1935 crash of the Navy zeppelin USS Macon off the California coast marked an inglorious end to a unique experiment in aviation. Four times longer than a modern Goodyear blimp, the Macon could carry 100 crewmembers, including pilots specially trained to fly small reconnaissance airplanes stowed in the zeppelin's massive hull. The giant airship was one of only two ''flying aircraft carriers'' ever built, and both went down in the ocean without ever seeing combat.