Airline Passengers(000)
American Airlines 88,241
Delta Air Lines 84,245
Southwest Airlines 74,787
United Airlines 66,100
Japan Airlines 58,241
Northwest Airlines 51,975
Deutsche Lufthansa 45,400
Air France 43,700
All Nippon Airways 42,251
US Airways 41,263
Continental Airlines 38,903
British Airways 35,132
Qantas Airways 28,884
Iberia 25,097
Korean Air 21,735
Ryanair 21,372
America West Airlines 20,047
Air Canada 20,043
Scandinavian Airlines 19,260
KLM 18,837
EasyJet 18,153
Air China 18,026
Thai Airways 17,301
China Southern 15,564
Malaysia Airlines 15,144
Alaska Airlines/Horizon Air 15,046
Saudi Airlines 14,488

These figures are from 2003, and the airlines with the oldest fleet are as follows;

Northwest's reliance on DC-9s -- the aircraft accounts for more than a third of its 432-plane fleet -- gives it an average plane age of about 18 years, according to data provided by BACK Aviation Solutions of New Haven, Conn. That ties with Aerolineas Argentinas for the oldest fleet among the world's top 60 airlines, according to BACK. By contrast, the average plane age of the other five hub-and-spoke airlines is about 10 years old. Houston-based Continental Airlines Inc., which went on a buying spree in the late 1990s, has a fleet that averages just eight years old.