The Boeing 737-100 entered service in 1968 and was the smallest variant of the 737 series. The 737-200 was an extended-fuselage replacement for the 737-100. There are no 737-100s in service today. The 737-200s are also being phased out due to poor fuel efficieny, high noise emissions, and high maintenance and operating costs, but quite a few are still used in "second tier" and cargo operations. Later versions of the 737 (300/400/500/600/700/800/900) with better performance and fuel efficiencies are still with the airlines, making the 737 a huge commercial success for Boeing.
|Dassault Mercure-100. Note the Pratt & Whitney JT8D powerplant, also used on the 737-100/200.|