North American airfares are now published four times a day during the week, after the Airline Tariff Publishing Company (ATPCO) added earlier this month a filing feed at 4 p.m. Eastern time to the already-existing feeds at 10 a.m., 1 p.m. and 8 p.m.

This means that, at any of those times, a certain fare can be put on the market, changed or pulled off the market. It also means that a fare’s entire lifespan can be as short as three hours.

The 4 p.m. feed had been planned for months, as I wrote in my book “Decoding Air Travel.” Although the airlines update their data 24 hours a day, ATPCO sends that data out to Global Distribution Systems (GDS), which are used by airlines and travel agencies to book flights, four times a day during the week. On weekends, there is only one feed at 5 p.m. ET.

“ATPCO started this new time for the U.S. and Canadian subscription data feed on Oct. 3,” said Jay Brawley, the company’s director of customer marketing. “The weekend feed remains the same.”

Located near Washington Dulles International Airport, ATPCO is owned by 16 of the world’s largest carriers and the Federal Express Corp. Its only and much smaller competitor is SITA, which publishes some fares in Europe, Africa and Asia.

ATPCO sends out feeds with international fares every hour, except for several hours on Saturday night, Brawley said. Discounted international fares typically stay on the market longer than discounted U.S. domestic fares — sometimes for weeks.

The official filing feeds don’t exclude the possibility that a fare may be changed or removed at other times on a booking source directly controlled by the airline, such as its website. In addition, the data changes in those feeds can take an hour or longer to update in various booking systems.

How do you know that a low fare to a city you need to visit has been published? You certainly don’t have to wait for the airlines to announce a sale — in fact, as I’ve written before, “sale” prices are often far from a bargain. Thanks to the transparency provided by the Internet, you can actually keep an eye on fares, through websites like and You can also subscribe to their e-mail alerts for fares between any two cities.

Reacting to a good fare — meaning booking it — quickly cannot be overestimated. In my book, I give an example of a missed opportunity from January 2008, when I was at the World Economic Forum in Davos, Switzerland, with then-Secretary of State Condoleezza Rice.

Just before she began her speech, I received an e-mail alert from FareCompare about a $99 one-way base fare between Washington and San Francisco. As it happened, I needed to book a trip to San Francisco, but I couldn’t act immediately, since I had to write and file a story for my newspaper. By the time I was free to look into booking a ticket, the fare was gone.

Not that there was anything I could have done in this case, but the experience taught me a valuable lesson: If you get word about a really good fare, book it as soon as you can. Most domestic fares usually stay on the market at least a couple of days, but there is never a guarantee, and some vanish within hours — the airlines can do whatever they want.

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