United Airlines, American Airlines, Continental Airlines, US Airways and TWA were among the carriers that posted notices on their Web sites announcing that they have suspended Internet-only discount fares since last week's terrorist attacks.
Although each airline calls them by a different name, Net-only fares are designed to promote sales over the Web, a less-expensive sales channel. Often the discounted fares are for flights leaving within days, marketed for travelers interested in last-minute getaways.
The airline sites were all still selling regular tickets.
A message posted at United Airlines read: "Due to the events of September 11, 2001, Domestic E-Fares are currently not available. Please check back as we will be offering you E-Fares again as soon as we are able."
A United spokeswoman said Wednesday that the airline's E-Fares were suspended indefinitely. She declined to comment further. Calls to the other airlines were not returned.
US Airways' site said there were "no domestic E-Savers offered until further notice." In an e-mail sent to customers, US Airways said its E-Savers program would not be offered this week.
TWA said its "Dot Com Deals" had been "suspended temporarily."
Travelers have shunned airports after the terrorist attacks, and sales of airline tickets are expected to drop sharply. The airline industry has reported losing at least $1 billion since last week and is seeking a multibillion-dollar federal bailout. In addition, several airlines have announced massive layoffs, and the top five U.S. carriers have cut their scheduled flights by about 20 percent.
The cutbacks come as Americans have embraced the concept of discount, last-minute fares on the Internet--promotions that airlines created in the mid-1990s as a way to sell more tickets on under-booked flights. According to a July survey by the Travel Industry Association, 42 percent of weekend travelers selected their destination within two weeks of their trip, and of those people, 17 percent cashed in on Internet promotions.
Last-minute cyberfares are especially popular with college students, retirees, freelancers and other leisure travelers who are long on time but short on cash. Typical deals require passengers to book tickets on a Wednesday or a Thursday, depart on the following Saturday, and return on the following Monday or Tuesday.
For people who can take advantage of last-minute travel, deals abound: It's not uncommon to find round-trip airfare from New York to Miami for about $175, Chicago to London for $350, or Los Angeles to Dallas for $150. Some airlines team with vacation planners and offer last-minute hotel and airfare packages to the Caribbean, Mexico, Asia and Europe for a fraction of the normal cost.
Philip Wolf, chief executive of Web research company PhoCusWright, said he thought that some of the airlines may have suspended e-fares because they were too busy worrying about other, more pressing issues such as passenger safety or grappling with spiraling sales to post the promotions.
Another reason may have been that offering price promotions the week of a national tragedy "may not have felt right" to some executives, Wolf said.
"These executives are very sensitive to aligning their marketing messages with current economic realities," he said.
The airlines could also plan to ignite sales by offering discounted fares via online travel agencies, such as Expedia, Travelocity and Orbitz, Wolf said.
Other airlines, including Alaska Airlines and Southwest Airlines, continued to offer Web-only fares after the terrorist attacks. And several airlines that suspended e-fares were offering other pricing promotions. For example, American Airlines suspended Net Savers but continued to offer discounts to senior citizens on AA.com.
Online travel sites also have been hard hit, with people canceling flights and flooding call centers to learn how they can rebook a canceled flight or get a refund. Since those sites operate as brokers, they mainly have been referring people to contact the airlines directly.
Online travel stocks have been among the biggest losers since the stock market reopened Monday, although on Wednesday, some were staging a recovery. Priceline.com fell more than 13 percent Wednesday. Sabre-backed Travelocity eked up almost 5 percent, however, and Expedia rose about 10 percent.