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During the early 1930's, airline routes across the North Atlantic were the most prestigious and profitable in the world. However, gaining new Atlantic air routes often proved difficult due to political and diplomatic delays. During this blog, we'll see how a fledgling airline was able to overcome this by developing a new concept in flights across the Pacific.

Pan American Airways, or Pan Am, was incorporated in 1927 by Juan T. Trippe, a World War I naval aviator, who affirmed a contract with the government to fly mail between Key West, Florida and Havana, Cuba. Pan Am's first passenger service began in 1928. Charles A. Lindbergh was a key pilot of the firm, as well as a surveyor of new air routes. By 1930 Pan American had a 12,000 mile route linking the United States, Cuba, Haiti, the Dominican Republic, Puerto Rico, Mexico, British Honduras (Belize), Panama and Colombia. With $2 million dollars already committed to trans-oceanic airliners (Sikorski S-42 and Martin M-130's), a Pacific service was the only option available to Pan American.

Pacific routes posed a much bigger challenge than crossing the Atlantic. The Atlantic crossings were a shorter distance-it was even possible to follow an extreme northern route where the longest over-water leg would be about 500 miles between Greenland and Iceland. Following the direct route between Newfoundland to Ireland, avoiding the cold weather of the northern route, was less than 2,000 miles. By contrast, the distance from San Francisco to Honolulu was nearly 2,400 miles, while the next step of the journey, from Midway to Guam was even farther. When Pan Am first began to consider trans-Pacific flights, the longest stretch it flew was less than 600 miles, between Kingston, Jamaica and Barranquilla, Colombia. At this time Juan Trippe and the Pan American management team considered an alternate route to the Midway-Guam run. Trippe and the Pan Am team researched a several possible alternatives and made the decision to use Wake Island, some 1,200 miles from Midway and 1,260 miles from Guam, as an ideal landing site. With Wake Island being utilized, Pan American's Pacific route was falling into place.

However, before Pan American could begin to fly Pacific routes, it had to establish facilities at the various bases along the way. For example, neither Midway nor Guam had facilities for Pan Am's aircraft, passengers, crew, weather and navigation equipment. In order to prepare its bases for service, Pan Am leased the freighter North Haven in early 1935, cramming it with long-distance direction-finding equipment, motorboats, construction equipment, 250,000 gallons of aviation fuel, a four-month supply of food, and approximately 120 laborers, engineers, demolition experts and an assortment of other workers. While its crew were still building bases across the Pacific, Pan Am began making a series of survey flights. The only aircraft in service with Pan American capable of conducting these flights was the Sikorsky S-42 flying boat, since the Martin M-130 flying boat was a year behind production schedule. The purpose of these flights was to test the performance of the plane against designated flight ranges. The S-42 fared well on all of the flight legs, except that of the San Francisco to Honolulu run (2,400miles), which it barely made. However, the S-42 had more than adequate fuel based on a reduced passenger load. On its return flight of April 1935, the S-42 carried the first airmail from across the Pacific. By October 1935 the survey flights were concluded with the S-42 proven to have the necessary range for the air routes.

In October 1935 the first Martin M-130 was delivered to Pan American. It was an improvement over the Sikorsky S-42, which entered service in 1934. The S-42 could carry up to 37 day passengers or 14 sleeper berths at a maximum speed of 182 mph and could cruise at 160 mph. While its ferry range was 3,000 miles, its operational range was only 1,200 miles. With additional wing tanks, the S-42 had a maximum range of 2,500 miles, making it capable of meeting Pan Am's requirement for each leg of Pacific service. The Martin M-130 had a larger passenger capacity than the S-42, with the 130 able to carry 46 day passengers with sleeping accommodations for thirty passengers in ten berths. It offered a maximum speed of 180 mph, with a cruising speed of 163 mph and a range of 3,200 miles-nearly 30 per cent more than that of the S-42. In 1939 the Boeing 314 flying boat began to replace the M-130s in Pacific flights. The 314 was a marked improvement in several categories over the previous flying boats in use by Pan Am. It could carry 68 day passengers or 36 sleeping, with a maximum speed of 210 mph, and a cruising speed of 188 mph. The Boeing aircraft had a maximum operational range of 3,685 miles, a fifteen per cent increase above the Martin M-130. All three of the flying boat types were four-engine aircraft, limited to take offs and landings on water. The 314 incorporated sponsons, broad lateral extensions, into the hull structure at the waterline. The sponsons served several purposes; to provide a wide platform to assist in floating the plane, act as a passage deck for entering and exiting the plane, and contribute to aerodynamic lift while in flight.

The first Clipper flight took place on November 22, 1935 with a Martin M-130 taking off from Alameda, California to deliver the first air mail cargo across the Pacific. The flight took just over a week with the M-130 aircraft delivering 110,000 pieces of mail to Manila, after stops in Honolulu, Midway Island, Wake Island and Sumay Guam. Both mail and passenger service were extended to Hong Kong on later flights. The Clipper Fleet never exceeded twenty aircraft, because a round-trip passenger flight from San Francisco to Honolulu cost $1,700 dollars-a huge sum during the mid-1930's. The flying boats experienced their share of crashes, with three aircraft lost; an S-42 in 1936 and two Boeing 314s, one in 1943 and the other in 1945. They were also expensive for their day, with a Martin M-130 selling for $417.000 in 1935. For all of the difficulty involved in establishing island bases, training crews and developing aircraft, the Clipper program was an overall success. The aircraft were comfortable for their day, as well as delivering both their passengers and cargo in a timely manner, crossing the Pacific in one-third the time of a cargo ship or an ocean liner. When World War II came, they were put into service of the United States Navy, serving throughout the war. However, the war hastened the end of the flying boats, as well, producing land based aircraft with intercontinental range, such as the Lockheed Constellation and the Douglas DC-4. Though the Clipper flying boats were retired from active service in 1946, one could consider the decade from 1935 to 1946 as the era of the flying boat.

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