The move could create a new stream of revenue for an aviation industry facing high fuel prices and other challenges. But it also could create new headaches as passengers retrieve sensitive e-mails and Web sites in confined quarters.
It also could end a common excuse people have to avoid checking "urgent" e-mail requests from their bosses. Unread magazines and books could now pile up as passengers devote their time aloft to electronic browsing.
American, a unit of AMR Corp., tested in-flight access on two flights on June 25. With Wednesday's launch, the airline is making service available for $12.95 per flight on its 15 Boeing 767-200 planes connecting New York with Los Angeles, San Francisco and Miami.
"Today the days of being cut off from the rest of the world while in the air become history," said Jack Blumenstein, chief executive of Aircell LLC, the company providing Internet services for American and other airlines.
Delta Air Lines Inc., Virgin America and US Airways Group Inc. are among the other airlines planning to test in-flight services.
JetBlue Airways Corp. offers free Wi-Fi service on one aircraft through its LiveTV subsidiary, limited to e-mail without attachments, instant messaging and some services from Amazon.com. Continental Airlines Inc. also plans to use LiveTV with similar restrictions.
Aircell's Gogo service is still formally a test, meaning American could drop it entirely after three to six months or expand it to other planes, depending on customer adoption and feedback. It can work with most laptops, Apple Inc.'s iPhone, some models of Research In Motion Ltd.'s BlackBerrys and other Wi-Fi-enabled devices.
The system will block Internet-based phone calls, giving passengers relief from chatty seatmates.
However, American and other U.S. airlines have said they will not filter sites based on their content, raising the prospect of passengers surfing racy material with kids nearby. Airlines say they already have general policies to address unruly passengers, and those would apply as they do now to passengers who browse adult magazines.
Less clear is how people reading corporate e-mail will fend off the snooping eyes of an extremely close neighbor.