Now that United is pairing off with Delta, and American is allied with US Airways, the world of frequent-flier miles threatens to become an even more complicated place. Here, gathered from various frequently flying experts, is a collection of old advice that still applies, and new advice to help travelers capitalize as programs overlap.
* Picture two pennies: When you're trying to decide where to travel when using your mileage awards, remember that frequent-flier miles from any airline should be worth about 2 cents apiece, if deployed shrewdly. (When airlines sell frequent-flier miles to businesses, they charge 2 cents per mile.) So if you've traded 50,000 miles for a trans-Atlantic flight that would otherwise have cost $1,000 (for a restricted coach ticket), you've done very well. If you've traded 25,000 miles for a medium-length domestic flight that would have cost $250, you're selling yourself a little short.
* Trust no one: Despite all their relentless number-juggling and efficiency in filling up jets and maximizing revenues, many airline alliances often seem to let frequent-flier credits (which are an expense, not revenue) slip through the cracks. Make it a habit to ask at the gate if your frequent-flier number is attached to your entry in the computer reservation system.
And even after you've done that, be alert for oversights: On a several-stop itinerary in Europe and the Middle East in May via Lufthansa, I checked at the gate before boarding every flight, receiving assurances that my frequent-flier account number was on the computer record and would be forwarded by Lufthansa to its partner, United Airlines. Yet three months later, one 5,786-mile trans-Atlantic segment of the trip is missing from my United mileage account. United's Mileage Plus representatives then conceded that the airlines made similar errors with about 30 percent of the passengers moving frequent-flier miles from Lufthansa to United this summer. A United spokesman, Andy Plews, confirmed the estimate, blaming the widespread shortchanging on data-transfer problems.
* Beware of high demand for Hawaii: The islands are massively popular as a mileage redemption destination, and now more travelers will be vying to go there. Randy Petersen, editor of Inside Flyer magazine, notes that US Airways doesn't go to Hawaii, but now that US Airways is allied with American, there probably will be a flood of US Airways customers trying to use mileage to get onto American flights to the islands. For veteran American mileage collectors, this means getting a flight to Hawaii may get tougher.
* Don't forget about expiration dates: So far, the new spate of frequent-flier alliances has done nothing to change expiration dates on miles, and most major U.S. carriers have them.
* Don't take foreign flights for granted, especially in Asia: The Delta-United alliance so far excludes foreign flights from its mileage-swapping options. And if you're flying with one of those widely admired Asian airlines that has ties to a U.S. carrier's mileage program, there are long-standing pitfalls. Some Asian carriers, including Cathay Pacific (partnered with American) and Singapore Airlines (partnered with American and Delta), give no mileage credits to those who buy coach (economy) seats, only to those buying business and first-class seats. Japan Airlines (partnered with American) gives restricted-fare coach travelers credit for 70 percent of miles flown. Thai Airways International (partnered with United) gives coach travelers credit for 50 percent of miles flown.
* Don't expect seasonal seat crunches to get any easier: Basically, the same number of passengers will be on board the same number of planes; these new alliances will just rearrange them a bit. And if you didn't try to use miles this summer, be warned that the current boom in travel has already made a tricky task trickier.
On June 26, hoping to use my accumulated SkyMiles to travel with my wife to England during August, I called Delta. I knew this was the busiest award travel period of the year and that the carriers a small number of seats set aside for award travel (they'll never say exactly how many). So I told Delta I could leave California from either LAX or San Francisco on Aug. 11, 12 or 13, and I would fly into either London or Dublin. Coming back, I could leave from London or Dublin, and land in San Francisco or LAX on Aug. 18, 19 or 20. Nothing available. Nothing on Delta, and nothing workable through Delta partners Aer Lingus, Sabena and Swissair.