British Airways Executive Club is pursuing its North American customers with a vengeance, offering one of its richest mileage bonuses ever.

U.S. and Canadian members who complete at least one transatlantic roundtrip in FIRST or Club World class between Jan. 13 and April 30 will earn a minimum of 50,000 miles.

BA is trying to make itself more relevant to the North American customer with the bonus, and is emphasizing that Executive Club miles may be redeemed not only for hops across the pond, but for domestic jaunts with partners American, America West and Alaska. The 50,000 miles earned through the promotion are enough for two free economy roundtrips within North America.

For each transatlantic roundtrip or two transatlantic one-way trips, members will be credited with 40,250 bonus miles in addition to the miles they would normally earn.

Why 40,250 bonus miles and not 40,000?

The additional 250 miles happens to guarantee a minimum of 50,000 miles per transatlantic roundtrip, no matter the Executive Club member’s point of origin in North America, status within the program or class of service in which he or she travels.

A Blue level member traveling in Club World from Montreal to London and back would earn 50,006 miles. A Gold level member traveling in FIRST from Seattle to London and back would be credited with 64,195 miles because of the greater distance traveled plus the Gold tier bonus and class bonus.

There is no limit on how many times members can earn the bonus.

The bonus may not be the richest in BA’s history – after all, Executive Club has previously offered a free ticket after two roundtrips in the past. The difference is that by earning miles, members are offered greater flexibility. They suffer from none of the restrictions or expiration dates that free tickets are subject to. We rate this promotion a “Must Fly.”

Registration is required. Visit http://www.ba.com/winteroffer to find out more.