The
            737 is the world's most successful jet airliner with over
            4,200 produced.
            The 737 was originally planned as a short-range
            small capacity airliner smaller than the  707 and 727.  The
            737-100 had a capacity of 100 and first flew in 1967.
            The second generation 737 (series 300-500) were
            updated to include efficient high-bypass turbofan engines.  The
            first 737-300 first flew in 1984.
            The next generation 737 (series 600-900) continued
            upgrading the original aircraft with more efficient engines, a new
            wing with greater chord span and area and larger tail
            surfaces.  The first next generation 737 first flew in 1996.