Thanks to the biplane's large payload capacity and low operating costs, Boeing Air Transport won the coveted air mail route from Chicago to San Francisco in 1927 and operated the route at a profit.
Powered by Pratt & Whitney's Wasp engine, the Boeing 40A could carry two passengers. Thanks to the biplane's large payload capacity and low operating costs, Boeing Air Transport won the coveted air mail route from Chicago to San Francisco in 1927 and operated the route at a profit.