If you're planning to travel by air anytime soon, you can expect to dig a little deeper into your pockets. The average roundtrip ticket within the United States, including taxes, reached $509.15 during the first six months of this year, up about $14 from last year.

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"It's mostly a result of airline consolidation, the fact that U.S. Airways and American have combined, Delta, Northwest, United, Continental and few new low-cost airlines have jumped in," said George Hobica, founder of Airfarewatchdog.com. "In the past, once the economy starts to improve, airlines increase the number of seats. That's not happening now. The airlines have not increased capacity, they're going after profit. The industry lost billions of dollars over the last 10 years."

Airfare has gone up nearly 11 percent in the last five years, after adjusting for inflation. The cost includes the fees and the taxes which are all rolled into the price of a ticket.

So, what's a traveler to do?

"I suggest people try to look at alternate airports," Hobica said. "For example, some people don't realize that Frontier Airlines is flying from Trenton to many destinations and some of the airfares are incredibly low."

There is no rule of thumb as to when to buy airfare and there is no magic day to buy a ticket, according to Hobica.

"Sometimes last-minute airfare is going to be cheaper, especially on international flights," he said. "There is no perfect day because airfares can go down at any second. For last-minute travel, I think Priceline's name-your-own-price bidding for travel model works quite well."

Packages may be the way to go for some because they use a completely different formula for airfare. Sometimes, if you purchase airfare plus hotel, it can actually save you money than if you just buy the airfare alone.

"You don't have to use the hotel, or you can choose to stay there if you want," Hobica said. "Either way, buying the package can sometimes save money."

For more information, visit www.airfarewatchdog.com.