For the time being, JetBlue is planning to offer Internet access only on a single Airbus A320, and only to those using Yahoo e-mail, Yahoo instant messaging, or BlackBerry models 8820 and 8320. Due to bandwidth limitations, users will not be able to download e-mail attachments or surf the Web.

The Wi-Fi-equipped plane will be dubbed "BetaBlue," and will be used to work out the inevitable kinks in system. There is no word yet on whether BetaBlue will remain on the NY-SF loop or will be used on other routes as well.

Not Exactly Broadband

Henry Harteveldt, vice president and principal analyst at Forrester Research for airline/travel industry research, who was invited by JetBlue on a trial run of the service, said he was not surprised that JetBlue is taking the lead in offering Internet access.

"JetBlue was the first to put satellite television on its flights," Harteveldt said. "They have been at the forefront of making flying pleasant for as many people as possible." The airline's core customer base, he added, is the so-called "millennial generation," the 18- to-40-year-olds who have embraced technology and want to be online constantly.

The BetaBlue's Wi-Fi service is being run by LiveTV, a unit of JetBlue that purchased a portion of the broadcast spectrum abandoned by Verizon Airfone, a venture that used to operate the ubiquitous seat-back phones. Verizon discontinued the service on commercial flights at the end of 2006.

The LiveTV system works by sending signals from an antenna on the airplane to base stations on the ground. The antenna is connected to an on-board server, which in turn reads signals from three Wi-Fi hotspots spread throughout the plane.

The distance the transmissions travel (nearly six miles from plane to ground) and the speed of the airplane (up to 500 mph) means that access is on the slow side (comparable to dial-up), and subject to occasional dropped signals as data transmissions are handed off from one base station to another.

More In-Flight Revenues?

As the kinks of the high-altitude Wi-Fi are worked out, JetBlue plans to roll out the service to the rest of its fleet, although no schedule for doing so has been announced. A handful of other domestic airlines -- including American Airlines, Virgin America, and Alaska Airlines -- are testing their own ground-to-air or satellite systems, and JetBlue may consider licensing its LiveTV service to competing airlines.

Most analysts see in-flight Internet as an inevitable development, and one that could generate some valuable additional revenues for the perennially cash-strapped airline industry. "If they choose to charge for it," Harteveldt said, "our research shows that even on a flight as short as one hour, 5 percent of leisure airline passengers would be willing to pay $10 for Internet access on that flight. On a longer flight, up to four hours or more, 45 percent would pay $10 for access."

Harteveldt added in-flight access could offer airlines other benefits, including justifying higher fares in general, preventing the loss of customers to other airlines, and advertising opportunities. "It's the classic captive audience," he said, "and one that could be an attractive marketing target for destination businesses like hotels, car rentals, restaurants, and so on."