How to find summer airfare deals

Everyone hoping to travel this summer is wondering whether to buy an airline ticket now or wait for a sale.

It's impossible to generalize, although I'd say that if you find a domestic fare under $250 roundtrip with taxes, or an international one in the $500-$600 range roundtrip, then you might want to grab it. And while it all depends on where and when you're going, and how flexible your travel dates are, here are a few clues as to what to expect:

Domestic U.S. travel

: Domestic airlines have cut capacity, and the merger of Delta and Northwest has reduced price competition. Airlines are determined to make a profit this year, or at least cut their losses. As a result, airfare sales aren't what they used to be

Southwest, which is reducing capacity by about 4 percent this year, recently announced a "breathtaking" sale on its Web site. Fares from Detroit to Milwaukee were listed at $298 roundtrip. Although we'll still see those $99 one-way loss-leader coast-to-coast flights here and there, most likely you'll have to travel on a Tuesday or Wednesday to avail yourself of one.

Traveling on Fridays and Sundays, and from Memorial Day until after Labor Day, will be the most expensive times to fly. If you're at all flexible, Southwest.com, Travelocity.com, Orbitz.com, Cheaptickets.com and Hotwire.com have excellent flexible date search functions.

European travel more expensive

International airlines have cut capacity and therefore are charging more for their seats. According to British Airways spokesperson John Lampl, his airline has slashed seats between London and the New York/Newark by 23 percent this year compared to last. Making matters worse, the British government has increased airport and other taxes tacked onto fares, and these are scheduled to increase further later this year.

Another ill omen is that this past winter was the first in memory that the airlines didn't have dead-of-winter, panicky sales to Europe. Last winter, and even last summer, we saw fares as low as $250 roundtrip, including taxes, to some European destinations. I'd be shocked if we saw a repeat this year. Even so, some European destinations will be cheaper than others, in part thanks to lower taxes and fees, but most destinations for summer travel this year will cost well over $1000 roundtrip with tax, unless a miracle happens and the airlines "say uncle."

Airfare alerts: Since airlines are anything but predictable, the best way to grab a cheap seat is to sign up for free airfare alerts. Needless to say, I'm partial to Airfarewatchdog.com's alerts, but over a dozen other sites also provide them, including Fly.com, Orbitz.com, Expedia.com, Travelocity.com, TripAdvisor.com/flights, Bing.com/travel, Farecompare.com, Kayak.com, Momondo.com, and Yapta.com. Each has its strong points. Find others by doing a Bing or Google search under "airfare alerts."

And sign up for airline frequent flier programs and e-mail alerts, because they often send out members-only deals and promo codes.

Another way to save: consider package tours. Last year, at the height of the financial panic, tour operators grabbed airplane seats and hotel rooms at favorable prices and locked in exchange rates. Depending on your travel plans, you may well find that a package tour to some international destinations costs not much more than airfare alone.

One other thing to keep in mind: the longer you wait to grab a fare, the less likely you'll get the seat assignment and flight times you want.