The largest family of airliners currently in service today are those that seat less than 180 people. All the major manufacturers have aircraft that fit into this category, the most successful being Boeing with its venerable 727 and 737 families-the combined production runs of both types have seen near on 5000 examples roll off the factory line since the early 1960s. The world` s largest aircraft manufacturer dominates this market sector, and all-new versions of the 737 like the –500, -600 and –700 series are only now entering fleet service.