Looking for a quick, cheap getaway? A bargain may be just a tweet away.

JetBlue and United airlines are offering their Twitter followers first dibs on some discounted fares, using the uber-trendy form of messaging to quickly connect with customers and fill seats on flights that might otherwise take off less than full.

Like the e-mails that many airlines began to send out in the 1990s, tweets are presenting a new, faster way to promote sales. And in fitting with this latest mode of instant communication, travelers have to decide quickly whether to fly.

JetBlue posted its first “Cheep” on July 6, a $9 one-way trip from JFK to Nantucket. Since then the carrier has generally notified Twitterers about sales on Mondays, giving them about eight hours — or as long as there are available seats — to book a trip for that or the following weekend.

“By promoting the Cheeps through Twitter, we give the already spontaneous audience of Twitter users a chance to grab great last-minute fares,” says JetBlue spokesman Morgan Johnston.

In addition to filling empty seats, the sales can introduce new customers to the airline, he says. “Those first-time customers trying Cheeps … we know they’re going to come back.”

United’s Twitter-only fares, also known as “twares,” started in May. The airline’s sales tweets can come at any time for a flight leaving on any day, and fliers have had to pounce quickly because the offers are usually available for only one to two hours.

“Twares are all about surprising our customers with low fares for a very, very limited time,” says Robin Urbanski, a United spokeswoman. And, she says, they “sell extremely fast because the prices are unbeatable.”

Many airlines continue to offer e-fares, notifying fliers about last-minute sales via e-mail. But travelers usually have a few days rather than a few hours to book their tickets.

With Twitter fares, Johnston says, “You really have to act fast. Because people watch Twitter in a real-time manner, the ability for someone to … come in and immediately act on it is a unique phenomenon to the culture of Twitter.”

Twitter is new enough that businesses likely are still trying to grasp who uses it and how that audience can benefit their enterprise, says George Hobica, founder of Airfarewatchdog.com.

“They’re experimenting with it to see what the value is,” he says. “Is it better to send an e-mail with a $9 fare or better to Twitter it?” Still, he says, “I think absolutely airlines and all travel companies need to get in the game and see how it plays out.”

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