The airlines, despite what we sometimes sound like around here, are not totally stupid. They know the miles for an international J award would cost a lot less than a ticket on the same flight. And they don't want to give up that revenue.

So, there are a few problems with this concept:

(1) The annual cap on the number of purchased miles you can put into an account is generally less than international J awards require. You'd be limited to an upgrade every other year (for one traveler) or a ticket every 3 years - or even less frequently for 2+ travelers.

(2) Capacity controls on awards mean that you cannot obtain an award ticket on popular routes without several months' advance planning. Front-cabin awards to Hawaii in the winter, for example, are often gone within a week of their becoming available 11 months before departure. Some airlines release additional award seats for elites, especially at the top level(s), but that's not an option in this case.

(3) Capacity controls on upgrades, if you want to buy an economy ticket and plan on an upgrade award, are likewise tight. (Ditto about elites.)

If you can figure out a way around these, you can make a lot of money selling the secret on eBay. Corporate America wants to do it, too!