Even take out the DC9 and 10, they still have 747-200 remember ? Other major world carriers had already phased out 742 several years ago, not until recently they have talks about to retired those 20+ yrs planes. Also as a launch customer to 747-400, they have the oldest 747-400, which are reaching 15yrs old (N661US-N670US), except several are delivered in the late 90s.