Today’s 747 has a large upstairs cabin because Trippe thought it would be a freighter, because a round hump produced too much drag, because Pan Am bosses had fond memories of the Stratocruiser’s bar (and all-night parties held by the light of the Pratt & Whitney R-4360s’ flaming exhausts), and because fuel prices went through the roof. Nobody set out to design the airplane with an upper deck. It came about because it was possible and because it adapted the 747 to a changing environment. It evolved.
