I fly frequently, more often as a "revpax" (revenue passenger) than as pilot. And I've mentioned before, given the two full-service options in Chicago (American and United), I long ago chose American as my preferred carrier. I have, in fact, been a member of their frequent-flyer program since 1988.
American is one of the two lynchpins of the oneworld alliance (typography and letter casing theirs), the other being British Airways. Only, they seem to hate each other's customers.
Exhibit: neither's customers can use or earn miles on the other's trans-Atlantic routes. Chicago to London? No choice, if you want your 3,953 elite-qualifying miles each way. Because miles are reedemable for travel and upgrades at up to 2c per (e.g., 25,000 miles for a round-trip domestic ticket that would otherwise cost $500), and elite miles are particularly valuable, BA's fare needs to be almost $100 less, all things equal, to make it worthwhile to fly the other airline.
OK, so I get that there are regulatory issues and other things they're taking into account. But I can hop a Japan Airlines flight to Tokyo and earn the same number of miles I can earn on a competing AA flight. So what gives?
It's even more peculiar when you start flying on BA flights on "domestic" European routes. Now it starts to annoy me.
Later this spring I'm flying to a European city to which the only reasonable connection is through Heathrow, and because it's a discount ticket, I'm only earning 25% of the miles flown for the trip. I could, of course, upgrade to a full-fare economy ticket for, oh, £200; but that's really not cost-effective, now, is it? I only discovered this by reading the fine print yesterday.
My conclusion will have to be, avoid BA flights when an alternative routing exists on another oneworld carrier. For example, to the place I'm going this spring, I could have flown American to another major European city and flown on Malév, Finnair, or Iberia, and gotten 100% mileage credit—and more miles to boot, because the routing is farther.
So again, why does British Airways not want American Airlines customers? Or is it American that doesn't want me flying BA?