Booking a flight online? Change your browser!

Travel experts -- and many of us who book air tickets online -- have long suspected that least some airline websites insert "cookies'' when you visit...which means your "fare'' can rise when you check back a few minutes later.

Case in point: You go online to an airline site, find a round-trip fare of $200 to New York. Then you shop around a bit and come back a few minutes later...only to find the fare has jumped by $75.

What happened? A number of possibilities. One is that the flight could have been booked in the interim by several other people. The automatic "yield management'' programs of the airline push the remaining inventory up a notch pricewise. So the only seats left are more expensive ones.

Another possibilities is the cookies scenario: The airline's computer recognizes your computer and nudges the price north.

How to cope? The easy answer is to open a different browser. (I keep both Internet Explorer and Mozilla Firefox on my computers for just this reason.) So if I went in on Mozilla the first time, I go in on Exlorer the next. (Another option is to go onto a colleague's computer.)

But what if the seats really have been snagged?

Well, listen to what happened to me this morning. Yesterday, I booked an itinerary for Miami - Rome - London, price of $646. Rather than purchasing the flight, I held it to be sure my husband -- who will meet me for a family wedding in London -- could get the same return flight.

When I went back to purchase the flight this morning, the price had kicked up to $2,100 plus! No way!

So I opened another browser and put in the search dates again. My original itinerary cost a mint, but there were a ton of other options at my same happy $646 price. And since the exact itinerary details aren't that important to me, I was prepared to make a change.

But...I did like the original itinerary, because it gives me lunch time in NYC on a Sunday, so I can catch up with a friend. So I killed the original itinerary that I had on hold, waited 5 minutes and repriced the trip. Sure enough, releasing the original seat knocked the price back down, and I got my original itinerary for $646.

A hassle? Yeah, somewhat. But when it comes to booking airline seats, I'm happy to beat the airlines at their own game.