The Boeing 727 was, for a very long time, the most popular jet-liner in the world. The 727 first took to the skies in 1963, and entered service a year later - much earlier than its bigger and more famous sister the Boeing 747.
The 727 design arose as a compromise between United Airlines, American Airlines, and Eastern Airlines over the configuration of the successor to the Boeing 707. United Airlines wanted a four-engined aircraft for its flights to high-altitude airports, especially its hub in Stapleton International Airport. American wanted a twin-engined aircraft for efficiency reasons. Eastern wanted a third engine for its overwater flights to the Caribbean. Eventually, the three airlines agreed on a trijet, and thus the 727 was born.
The 727 has proved very successful with airlines world-wide because of its capability of landing in smaller runways while flying medium range routes. This effectively allowed airlines to attract passengers from cities with large populations but smaller airports to worldwide touristic destinations. One of the features that gave the 727 its ability to land on shorter runways was its unique wing design. Through flap extension and leading edge slat deployment, the 727 could almost double its wing surface area, allowing it to fly with great stability at very slow speeds.