Boeing 377

The Boeing 377 Stratocruiser was a large long-range airliner developed from the C-97 Stratofreighter military transport, itself a derivative of the B-29 Superfortress. The Stratocruiser's first flight was on July 8, 1947. Its design was advanced for its day; its innovative features included two passenger decks and a pressurized cabin, a relatively new feature on transport aircraft. It could carry up to 100 passengers on the main deck plus 14 in the lower deck lounge; typical seating was for 63 or 84 passengers or 28 berthed and five seated passengers.

The Stratocruiser was larger than the Douglas DC-6 and Lockheed Constellation and cost more to buy and operate. Its reliability was poor, chiefly due to problems with the four 28-cylinder Pratt & Whitney Wasp Major radial engines and their four-blade propellers. Only 55 Model 377s were built for airlines, along with the single prototype.

The Boeing 377 Stratocruiser was a civil derivative of the Boeing Model 367, the Boeing C-97 Stratofreighter, which first flew in late 1944. William Allen, who had become President of The Boeing Company in September 1945, sought to introduce a new civilian aircraft to replace reduced military production after Second World War. Although in a recession in late 1945, Allen ordered 50 Stratocruisers, spending capital on the project without an airline customer.

On November 29, 1945 Pan American World Airways (Pan Am) became the launch customer with the largest commercial aircraft order in history, a $24,500,000 (equivalent to $325,900,000 in 2016) order for 20 Stratocruisers. Earlier in 1945 a Boeing C-97 had flown from Seattle to Washington, D.C. nonstop in six hours and four minutes; with this knowledge, and with Pan Am President Juan Trippe's high regard for Boeing after their success with the Boeing 314 Clipper, Pan Am was confident in ordering the expensive plane.