Airlines used to be a little uneasy about the PCs and other portable electronic devices that passengers bring on planes, and flight attendants still tell passengers to switch them off during takeoff and landing.

But airplane manufacturer Boeing now says the time has come to invite people to log on while they're airborne. Books, newspapers, magazines, and movies just aren't supplying enough in-flight entertainment to the ever-connected flying public, the company contends.

The aerospace corporation last week announced Connexions by Boeing, a service that it will sell to airlines. Connexions makes it possible for airlines to offer passengers high-speed data communication services via satellite on board almost any flight.

Passengers will be able to plug their PCs into the system at their seats and surf the Net, send and receive e-mail messages, and even access their corporate intranets.

Eventually, Boeing plans to make Internet-enabled devices available on the backs of aircraft seats for people who don't carry PCs. The service could show up on commercial flights by the end of next year.

In addition to the pay Internet service, a free package of information and entertainment will be available, including a selection of "real-time" television programming, as opposed to the taped TV programs now played on some long flights.

CNN has already signed up to provide live programming, but other networks can sign up as well, says Ric Vandermeulen, director of strategy and planning for Connexions by Boeing.

The free service also will offer information about on-board shopping, travel, and the flight's destination. The technology Boeing developed to support the system includes a phased array antenna that is mounted on top of the aircraft's fuselage.

The antenna, which is less than 2 inches high, 44 inches wide, and 55 inches long, is fixed and doesn't interfere with the aerodynamics of the plane or its own communications systems, Simonsen says.

Electronic modules inside the antenna move to maintain the connection to satellites at a maximum transmission speed of 5MB for downloading data and 1.5MB for uploading it.