Fasten your seat belt, return your tray table to its upright position and sign off the Internet.

On Wednesday, the Federal Communications Commission approved a plan that may have fliers sending e-mail, researching reports on the Web and shopping online within a few years.

The FCC also launched an inquiry Wednesday to see if it should relax restrictions on cell-phone use in flight.

The Federal Aviation Administration, which prohibits cell-phone use on planes because of safety concerns, is already studying its ban and expects to issue a report in 2006. It could need another year to change its rules.

Together, the efforts could significantly change commercial flight and create new revenue opportunities for airlines and communications companies, aviation experts and industry officials said.

But they tempered their remarks, adding much work needs to be done in allocating spectrum, addressing interference issues and creating viable business plans.

FCC officials say they plan to auction wireless licenses for Internet use by the end of 2005. Industry officials say it would take another year to set up a network.

When fully operational, the network could provide up to 2 megabytes per second of data to planes. Because everyone on board would share the connection, access speeds could be slower.

It’s unclear which companies would charge passengers for the airborne Internet service. If it’s reasonably priced, consumer groups say, it could be a hit.

“There would be some substantial interest from both business travelers to keep up with e-mails and leisure travelers,” said David Stempler, president of the Air Travelers Association.

Fort Worth, Texas-based American Airlines Inc. said its passengers want both Internet and cell-phone service.

“We’re confident that business fliers want to stay connected while they’re flying and that leisure fliers want to stay connected – and also to be entertained,” said Tim Wagner, an American spokesman.

American tested a system with Qualcomm Inc. in July that allows users to make cell-phone calls onboard. The plane was outfitted with a miniature radio transmitter, called a “picocell,” that directs calls from the plane to the ground with the help of satellites.

The Internet system under discussion Wednesday at the FCC would not use satellites.

Instead, antennas on board would communicate with a network of wireless transmitters on the ground. They would use the same wireless frequencies that connect existing seatback phones from Verizon Airfone.

At least two rival corporate camps have emerged to bid on the broadband licenses.

FCC officials said two winning bidders will be selected, but one may only get a fraction of the wireless airwaves needed to provide true broadband service. The commission said it would split the licenses two ways, depending on which received the highest bid:

Two companies would share overlapping 3-megahertz licenses.

One would get 3 megahertz and the other would get 1 megahertz.

The communications and aviation industries have had heated arguments about which approach should be taken.

One group, led by Boeing Co. and AirCell Inc., say two licenses should be awarded to ensure competition would bring lower prices. They say rivals can feasibly share wireless spectrum. Several airlines have filed comments with the FCC backing their approach.

“The process, as it plays out, may not yield the desired effect of providing competition in broadband services to airline passengers,” said Jack W. Blumenstein, AirCell’s chairman and chief executive.

But Verizon Airfone, a division of Verizon Communications Inc., says sharing spectrum would create myriad technical problems and hobble both services. The company, which is the last to offer seatback phones, says only one 3-megahertz license should be awarded to ensure always-on, fast service.

“We are not trying to create a monopoly,” said Bill Pallone, president of Verizon Airfone. “They need to find additional spectrum so there can be additional providers.”

FCC officials said there isn’t more spectrum readily available today. Chairman Michael K. Powell said the agency would try to expand competition by allowing satellite and cellular-phone providers into the cabin in the future.

“We will continue to explore opportunities for further competition in other bands and other platforms,” he said.

Boeing offers a high-speed satellite-based service, Connexion, to several airlines in Europe and Asia. But it hasn’t been able to get U.S. carriers to sign a deal. A spokeswoman said the plane-maker hasn’t decided if it will bid in the FCC auction.

Q. What’s the situation today?

A. Only one provider, Verizon Airfone, offers seatback phone service on commercial planes.

Cell-phone use is prohibited by the Federal Communications Commission and the Federal Aviation Administration.

Q. What happened Wednesday?

A. The FCC says it will allow broadband Internet service using the wireless frequencies that are used for Airfone service today. The FCC sought public comment on whether it should relax its cell-phone ban.

Q. What’s next?

A. Licenses for the broadband frequencies will be auctioned late next year. Industry officials say it would take another year after that for service to start.

An FAA research group is expected to issue a report on the safety implications of cell-phone use on planes by 2006. It could take another year after that before the FAA could lift the ban.