Have you ever selected an airfare online and then once you click on it, it’s suddenly not available?

Here’s what you need to know so you aren’t caught off guard by misleading fares.

The reality is, online search engines can’t access real-time data fast enough to keep up with search result demand, so you may be seeing fare estimates based on old data.

Some sites have two systems, one for tracking airfare, and one for booking.

It isn’t until the consumer goes to buy the ticket that the agency confirms the price with the airline.

How can you get around it? Be a comparison shopper and look at as many resources as you can, like Kayak and Momondo, in addition to the airline Web sites.

Don’t forget AirfareWatchdog.com, which has actual human beings scouring the Web for deals.

And speaking of human beings, pick up the phone and call the airline.

Contrary to popular belief, online travel agencies don’t necessary have all the inventory, so the person at the other end of the line may be able to find you a better deal.

Get more info on air travel in our Airlines & Airports section.

And for more money-saving tips, check out the Budget Travel section.

And check out the rest of our Daily Travel Tips here.