From The Airport Wiki

The Boeing 314 “Clipper” was a long-range flying boat produced by the Boeing Airplane Company between 1938 and 1941. One of the largest aircraft of the time, it used the massive wing of Boeing’s earlier XB-15 bomber prototype to achieve the range necessary for flights across the Atlantic Ocean and Pacific Ocean. Twelve Clippers were built for Pan American World Airways, three of which were sold to BOAC in 1941 before delivery.