If you're flying this summer, be prepared to kiss your family goodbye at the gate -- even if they're on the same plane.
Airlines are reserving a growing number of window and aisle seats for passengers willing to pay extra. That's helping to boost revenue, but also making it harder for friends and family members who don't pay this fee to sit next to each other. At the peak of the summer travel season, it might be nearly impossible.
Buying tickets two or more months in advance makes things a little easier. But passengers are increasingly finding that the only way to sit next to a spouse, child or friend is to shell out $25 or more, each way.
With base fares on the rise -- the average airline round-trip ticket this summer is forecast by Kayak.com to be $431, or 3 percent higher than last year -- some families are reluctant to cough up more money.
Airlines say their gate agents try to help family members without adjacent seats sit together, especially people flying with young children, but there is no guarantee that things will work out.
Not everyone is complaining, however.
Frequent business travelers used to get stuck with middle seats even though their last-minute fares were two or three times higher than the average. Now airlines are setting aside more window and aisle seats for their most frequent fliers at no extra cost.
"The customers that are more loyal, who fly more often, we want to make sure they have the best travel experience," says Eduardo Marcos, American Airlines' manager of merchandising strategy.
For everybody else, choosing seats on airline websites has become more of a guessing game.
To travelers who haven't earned "elite" status in a frequent flier program, flights often appear full, even though they are not. These casual travelers end up paying extra for an aisle or window seat believing they have no other option.
But as flights get closer many of the seats airlines had set aside for those willing to pay a premium do become available -- at no extra cost.
"Airlines are holding these seats hostage," says George Hobica, founder of AirfareWatchdog, a travel website. "The seat-selection process isn't as fair as it used to be."
Airlines are searching for more ways to raise revenue to offset rising fuel costs. In the last five years, they have added fees for checked baggage, watching television, skipping security lines and boarding early.
Now they are turning to seats.
Since last summer, American, Delta Air Lines, Frontier Airlines and United Airlines have increased the percentage of coach seats requiring an extra fee. Some -- like those on Delta, JetBlue Airways and United -- come with more legroom.
Others, including those on American and US Airways, are just as cramped but are window and aisle seats near the front.
Allegiant Air and Spirit Airlines go one step further, charging extra for any advanced seat assignment. On Spirit, passengers who aren't willing to pay the extra $5 to $15 per flight, are assigned a seat at check-in. The computer doesn't make any effort to keep families together.
If a young child is separated from a parent, "we just have to get it done," says Frontier spokeswoman Lindsey Carpenter. "Usually, people are pretty accommodating."
If all else fails, see if nearby passengers are willing to switch. There might actually be some good manners left on planes. If not, offer to buy them a drink.