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You may already have an airline-affiliated credit card. British Airways is hoping that you'll sign up for theirs, too.

Introducing the British Airways Visa card from Chase.

Sign up, and you'll get 50,000 BA Executive Club Miles after your first purchase, and 50,000 additional miles after you make $2,000 worth of purchases on the card over three months. It's by far the speediest way to earn a free overseas trip.

Frequent flier miles guru Gary Leff at A View From the Wing has been on top of this story like nobody else. He's seen nearly every sign-up offer to come along in the past decade. So what does he think of this 100,000 mile sign-up bonus?

"Wow.… It's just incredible. I genuinely don't remember the last time I was blown away by a credit card offer."

What's the annual fee? $75, no higher than similar cards with far less generous fees.

You may apply online now, but the card doesn't go into effect until next Monday, November 16. The offer may expire as soon as November 30 or as late as 90 days from now, depending on how things go.

British Airways spokesperson John Lampl confirms that anyone who had the British Airways co-branded Visa from Chase in the past is still qualified to sign up for the new card, as long as they're not currently cardholders. That's unusual. Airlines typically save their juiciest sign-up bonuses only for completely new customers.

Bonus perk: Nab $50 off round-trip tickets bought via BA's website when you use the new card for booking through December 31.

So what are the catches?

British Airways adds fuel surcharges on their award travel. These surcharges can be roughly betweem $135 and $200 per roundtrip. Plus, British Airways fares have tended to be somewhat higher than competitors on major routes that Americans commonly fly, according to our recent fare searches.

Leff has a tip for maxing out the card. He points out that you can earn a free companion ticket after you spend $30,000 on the card in a year. For most of us, spending $30,000 on a single credit card in 12 months is a tough trick to pull off. But small business entreprenuers might be able to do it easily.

As Leff writes:

British Airways allows 'households' to pool their miles for an award. So two people each sign up for the card. One puts $2,000 in spend to earn the full bonus, the other puts $30,000 in spend to earn a companion certificate. 240,000 miles will be earned, plus a companion certificate. This would allow two people to redeem first class tickets between, say, Los Angeles and Dubai. In other words, 480,000 miles of awards for nothing but $32,000 in credit card spend.

In an e-mail exchange, Gary clarified that you'd want to start toward the $30,000 goal in January, not now. "The cycle for counting $30,000 in spending towards the free companion award ticket runs with the calendar year (so any money spent now is 'wasted')."

As always, be wary of trying to "game the system" by applying for the card to earn the points and then canceling. On the one hand, you may want to reevaluate whether you want to keep the account after the first year, given that other cards will have cheaper annual fees. But on the other hand, closing credit cards can hurt your credit score.

The reason: A key factor in your credit score is how much credit you've had available over your lifetime, not just at any given moment. Whenever you close an account, you ding yourself, which may matter if you plan to apply for a loan for a car or a house in the near future.

British Airways Visa Chase card info page

EARLIER
British Airways supersale, happening now

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Live Well, Get Miles: Our 2009 newbie's guide to frequent flier miles

ELSEWHERE
Ever dream of having a boatload of frequent-flier miles—plus the free automatic upgrades and private airport lounge access that goes with premier status? Do you also plan to fly more than 5,000 miles in the coming year? Then you may like Frequent Flyer Master, a 40-page e-book that costs $49. I bought a copy when it debuted last week, and even I (who thinks about travel strategies every day) learned a few tricks. My favorite part: Six months' worth of e-mail updates and deal alerts. There's no other up-to-date primer on the basics of the frequent flier system, primarily for domestic U.S. travel and round-the-world tickets. But if you already understand the basics, this guide probably isn't for you.

UPDATE Nov. 25:
A spokesperson for Chase Card Services notes:

"The offer is (obviously) subject to credit approval. If a customer does not qualify for a British Airways Signature Visa, they may qualify for a British Airways Platinum Visa. Both cards have the same enhanced earn rate and the same premium bonus offer (100,000 miles).
There is not any other alternative card – customers either qualify for the British Airways Signature or Platinum cards (both of which have the same bonus and new earn rate) or they are declined and do not receive any card."