Originally Posted by
billgrates3
don't forget that BE upgrades only work for certain fare codes. Generally the deep discount econ fares are not eligible. So if you ever use the points for econ tickets, you'll need to find out the fare inventory from Amex before they purchase the tickets.
Yes, you're right--B, Q, N, O, S fares are not eligible for BE upgrades, and generally the lowest fare that is eligible is G (or sometimes V if G isn't available)--but OP was asking about using a BE upgrade to go from J to F. IIRC all domestic J fares (J, C, D, I) are eligible for the upgrade.