Boeing 307 Stratoliner USA Only ten Stratoliners were built. Three Stratoliners were built for Pan Am; five served with TWA, and a ninth Stratoliner was supplied to Howard Hughes. (Photo: Jesse Davidson Archives) Boeing Model 307 Stratoliner was the first fully pressurized airliner to enter service anywhere in the world, Boeing's 33-seat Model 307 Stratoliner of 1938 employed the wings and tail ...