Star Alliance frequent flyer program Avianca LifeMiles is offering a purchased miles bonus through May 29 — a minimum of 100% bonus for everyone, but 120% for residents of certain countries.

If your account is registered outside of Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Nicaragua, Panama, and the United States it’s a 120% bonus instead.

That would bring down the cost from 1.65 cents per mile to 1.5 cents per mile. The 20% discount doesn’t materially change the value proposition. It can be a good deal with a specific use in mind for the miles, and you can buy up to 75,000 miles (plus bonus — so receiving 150,000 for US residents).

I don’t like investing in LifeMiles speculatively though. In the past they’ve tweaked some award prices without notice.

When Avianca joined Star Alliance I declared their program the most generous in the alliance. They are part of my “Devaluation Plan B” which is to look to international frequent flyer programs for value if and when US programs devalue further.

There are no fuel surcharges and they offer one-way awards many of which are priced reasonably. They also offer ‘cash and points’ which means that as long as you have 40% of the miles needed for an award you can buy the rest at the time of redemption.

That said, their call centers are frustrating (if you can wait a day for a reply, they’re better over e-mail) and they don’t permit “mixed cabin” redemption — so if you are redeeming a transatlantic business class award, all segments need to be in business class (including domestic US flights, and intra-Europe flights). And the award chart isn’t as good as it once was.