The discount for upgrades after 25 years is equal to the coach price charged for the segment. Example:

SAN-JFK
0-5 years:
Y: $12.00, F: $32.45

5-25 years:
Y: $0.00, F: $32.45

25+ years:
Y: $0.00, F:$20.45

The low end charges (based on SAN-LAX... at 109 miles) are Y: $4.68/F: $11.92.

On long haul international flights, they use flat rate pricing, rather than mileage based.

US-Europe/Deep South America:
0-25 years:
Y: $35.00, J: $60.00, F: $100.00

25+ years:
Y: $0.00, J: $25.00, F: $65.00


US-Asia:
0-25 years:
Y: $50.00, J: $100.00, F: $175.00

25+ years:
Y: $0.00, J: $50.00, F: $125.00

All of these are the service charge only, before taxes/fees.