U.S. airlines are now piling on to the in-flight Wi-Fi bandwagon, with Alaska Airlines joining other airlines in expanding the service to more aircraft.More than 2,100 passengers have used the service since it was offered in a free trial run on one plane beginning Feb. 26, the airline said Tuesday. Alaska will now go ahead with installing the system on more aircraft in the coming months and testing prices. Other U.S. airlines have also forged ahead with in-flight Wi-Fi, which is re-emerging with new technology after the demise of the Connexion by Boeing service in 2006. On March 31, American Airlines said its service had come out of the trial stage and systems would be installed on more than 300 domestic planes over the next two years. In December, Virgin America began commercial Wi-Fi service after a brief passenger trial and committed to rolling it out on its full fleet of 28 planes. Delta Airlines said last year it would have Wi-Fi on its entire fleet of 330 planes by the end of summer 2009. United Airlines started offering the service on 13 craft in January. Alaska uses a different system from most other U.S. carriers. Because so many of its flights go over inaccessible stretches of the nation's largest state or travel over the Pacific to reach it, Alaska is using a satellite-based system from Row 44. Southwest Airlines also uses this system, which connects an on-board Wi-Fi network with the Internet via satellite. The other major U.S. airlines are working with Aircell, which links planes to the Internet via special 3G radios on the ground. The airline said it was pleased with the response to Gogo. More than 96 percent of the passengers who used it and filled out a survey said they would use it again, and more than 75 percent rated it "excellent" or "very good," according to the airline. About 35 percent of those passengers accessed the Wi-Fi network with mobile devices such as smartphones rather than with laptop computers. Alaska said it planned to start evaluating pricing models this week and will set a final price later this year. Aircell charges US$9.95 for flights of less than three hours and $12.95 for longer flights, with a special $7.95 price for access from a handheld device on any type of flight. With so many airlines going ahead with in-flight Wi-Fi, rolling it out has become a matter of remaining competitive, said wireless analyst Jack Gold of J. Gold Associates. It's still not clear whether the service will turn a profit for the airlines, which will be the key test of its success as a business, he said. At $12.95 for a coast-to-coast flight, an executive who flew 100 times a year might spend nearly $1,300, which employers might not cover for anyone other than top executives. Gold expects services such as Boingo to appear, giving flyers access to multiple airlines' in-flight services at a bulk rate. "Otherwise, it gets real unattractive very quickly. ... It's a lot of money," Gold said. Airlines may also start to engage in price competition on the service, he added.