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In June 1986, Boeing announced the development of the 737-400, which
stretched the fuselage a further 10 ft (3.0 m), increasing the passenger load to
188. The -400s first flight was on February 19, 1988, and, after a seven-month/
500-hour flight-testing run, entered service with Piedmont Airlines that
October.
The -500 series was offered, due to customer demand, as a modern and direct replacement of
the 737-200. It incorporated the improvements of the 737 Classic series, allowing longer routes
with fewer passengers to be more economical than with the 737-300. The fuselage length of
the -500 is 1 ft 7 in (48 cm) longer than the 737-200, accommodating up to 140 passengers.
Both glass and older-style