Delta is the largest airline in the US in terms of passengers and they have a great piece of the pie on the Eastern Seaboard of the US with hubs in CVG and ATL and a large focus in BOS, MCO, LGA, and JFK. Delta is replacing the 727s with 737-800s and the L-1011s with 777s and 767-400ERs. Delta also owns its regional carriers ASA and Comair and last week placed the largest single order in history for the CRJs. If you want to talk about an airline that uses old planes and large planes on "commuter" routes look at NW. NW flies mainline DC-9s from DTW-TVC, DTW-Flint, DTW- Bay City. NW flies 170+ DC-9s, 35 727s, 40-45 DC-10s, and 24 747-100s/200s.