The thing I forgot to mention is say you have a 339 aircraft fleet of DAL 88s, 90s, used 90s, Saudi 90s, AAI 717s and Midwest 717s you'd have 65% of the fleet under 14 years old and half of those under 10. All of them acquired for a fraction of their original cost or especially a fraction of a new 737/320z The 88s would have the highest age but even then its an average of 20 years from a family of jets whose first generation proved 40+ was viable without hardly any updates much less the cockpit upgrade the board may approve.