For some travelers, it can be a frustrating part of booking flights online: Seeing the price go up when they click to book the fare.
When NBC 5 recently tried to book a round-trip flight on American Airlines' website from Oklahoma City to Los Angeles, the price of the outbound flight increased $54 dollars within seconds. The inbound and outbound flights both had the same quote — $168 — but when AA.com took NBC 5 to the booking page, the outbound flight was $222.
The Wall Street Journal coined it "fare-switching."
Fort Worth-based American Airlines said the problem is rare and only happens to a handful of customers.
"This 'problem' isn't really a problem. It does happen but very rarely," the airline said in an email. "Tickets are limited on any given flight, and it's first-come, first-serve. In the case you described, someone who wanted that seat was a few seconds ahead of you in the booking process and simply clicked before you could get the last ticket in that fare category on that flight."
Airline industry expert Rick Seaney, CEO of Farecompare.com, said he thinks it's a technical glitch..
"I don't think for online shopping that they have much control over that," he said. "They're using a third party, actually, at American to do their quotes."
Seaney said the glitch affects 2 to 3 percent of bookings.
"There are at least five or six different major engines in the marketplace, and they all have the same problem," he said. "They all use this strategy, which is, 'I have to take a snapshot of the inventory and give that to consumers,' but it doesn't reflect what is the last seat sold on that flight."
American would not say if it used third-party vendors to manage AA.com.
But customer Nicole Simon said she has sworn off AA.com. Her fare jumped within several hours while she was shopping on AA.com for a family vacation from North Texas to Miami.
"I still don't understand how they can do that to people," she said.
She saw the flights she wanted while she was work, but her credit card was at home. In the five-hour span it took to for her get back online, the fares to Miami were gone.
"I got home a couple hours later, and the ticket shot up by $90," Simon said.
Fares on all airlines can change within hours, but Simon said American should honor the quotes.
She booked the higher fare for her Miami trip. When she checked fares on AA.com the next day, the lower price was quoted again.
"The next day, I called because the ticket price had shot back down, so within 48 hours the price was back down to where it was before," Simon said.
But an agent told her she was out of luck. The airline told Simon the fare had have $150 difference before it would make an adjustment. Otherwise, there would be a $150 re-booking fee.
American commented on Simon's case, saying in an email that it was "a hard one to explain."
"There could have been a 24-hour hold on the reservation that was made before hers, and the folks decided to let it cancel, thus popping that fare back into inventory," the airline said. "Once ticketed, there is a $150 change amount, so if the fare is less, it wouldn't be worth re-issuing the ticket."
Seaney said fare-switching happens because of the way AA.com is set up.
He said there are two engines -- the shopping engine that serves up thousands of available ticket quotes, and a separate booking engine with the actual "hard sale" seats on the plane. When a customer goes to book on AA.com, the two different engines don't always match, he said.
"I think what they [American] should do is take it under advisement -- talk to their technology folks and say, 'Look, we have some mismatches going on,'" Seaney said.
Seaney said airlines do not save cookies or previous booking information to charge certain customers more, as some travelers believe.
But he said Tuesdays at 2 p.m. is the best time to shop online for tickets. At least one airline puts on a fare sale Monday evening. The other airlines scramble to match it, and those fares hit the reservation center at about 2 p.m. Tuesday. Those deals can often run through Thursday, Seaney said.