If you have big vacation plans this summer you won't want to hear this. That trip could cost you big time as the price of plane tickets are expected to double or even triple in coming months. Industry experts caution -- prices are getting worse.

"To the point where it could be double in a lot of cases," said Paul Glenn, Executive Travel.

That's not good news, considering prices are already surprising travelers.

"The tax is what? It was $100 tax per ticket," said Deb Engelmeyer, Normal, Ill.

"If I hadn't gotten the free ticket, I probably wouldn't be making the flight," said Cynthia Erickson, Denver, Colo.

Glenn said increased petroleum costs are a contributing factor..

"Every quarter you're seeing losses of millions if not hundreds of millions of dollars by the airlines. The fuel prices, their continual rise is dramatically increasing their expenses," he said.

Those travelers considering summer vacations find themselves thinking again.

"It depends how much they spike, but in the same way, I have to monitor how much I drive because of the cost of gasoline. It will be the same with air travel," said Jon Munk, Butler County.

Some are even brushing up on their math skills, calculating the cheapest way to their final destinations.

"Probably won't fly. Probably have to drive or AmTrak. I know that's not very convenient time-wise, because sometimes those get delayed, too, but it's probably cheaper in the long run," Engelmeyer said.

"We've done the analysis, and even for the two of us to fly, it's still cheaper than driving, but if the prices really go up, we'll consider driving again," said Chuck Hibberd.

Higher prices may bring less business for travel companies this summer, Glenn remains hopeful.

"We do expect it to be down from what it has been in the past, but that's not to say it's not going to come back," Glenn said.

Glenn said a year ago he could find an airline ticket to Seattle for $300 or $400. This month that same ticket is selling for $700.

Glenn's advice to travelers is to book now, because every day you wait it only gets worse.