NEW YORK Warren Adelman's colleagues know him as "Thumbs": Like many executives, he is adept at checking e-mail on his BlackBerry and does it almost constantly.
Unable to do so during flights, Adelman welcomes business trips as "an opportunity to decompress a little bit from the constant flow of e-mail, perhaps catch up on a book."
"It's one of the few downtime environments you get in this day and age," said Adelman, president and chief operating officer of GoDaddy.com Inc., a registration company for Internet domain names.
An invasion of his sanctuary is imminent, though, as airlines around the world would make available in-flight Internet services.
JetBlue Airways Corp. this week began offering e-mail and instant messaging on one aircraft. Broader high-speed services, including Web surfing, are to come next year on some flights of AMR Corp.'s American Airlines, Virgin America and Alaska Air Group Inc.'s Alaska Airlines.
And in-flight entertainment provider Panasonic Avionics Corp., a unit of Matsushita Electric Industrial Co., has been testing Internet offerings with Australia's Qantas Airways Ltd. Other airlines are to join next year.
Airlines see airborne Internet access, which typically uses Wi-Fi technology deemed safe for flights, as producing both revenue and a competitive edge against one another and over trains, buses and automobiles.
Frequent fliers said the temptation to go online would be overwhelming, though they were divided over whether they would rejoice.
Jay Pease, a regional marketing director for Exstream Software LLC, said he needs to rest during trans-Atlantic flights for morning meetings in Europe. But he often has trouble sleeping, and he worried that "the temptation would be there to say, 'I'll just log on and surf the Internet for a while."'
Jon Carson, chief executive with online fund-raising company cMarket Inc., said that between kids, meetings and electronic interruptions on the ground, "I get some of my best work done on the plane."
Good decisions and breakthroughs often arise from "the kind of deeper, reflecting thinking" not possible when new messages continually arrive, Carson said.
Adelman's colleague, GoDaddy General Counsel Christine Jones, disagreed.
"I would seriously turn cartwheels," said Jones, who admits to responding to e-mail while sitting in church. "The carriers that don't offer it will start hearing from their customers, your frequent fliers, 'Hey guys, you have to get on board with it."'
Peter Allen, chief marketing officer for the management consulting company TPI, said he already spends 80 percent of his flights on his laptop often catching up on e-mail and waiting for an Internet connection upon landing to transmit those messages.
Robert Tas, chief executive of the online advertising company Active Athlete Media Inc., said he usually winds up reading printouts of articles, reports and other items he could read online. And if he had Web access he could dig deeper into items of interest.
"Reading time is still important," Tas said. "Having the Internet would allow me to do it more efficiently."
Frequent travelers said catching up with e-mail in the air frees up their time at their destination in the hotel or back home with family.
"If I ended up feeling bad about it and resenting it, I would turn off my computer," said Andy Halliday, chief executive of the collaborative tribute site Tribbit.com. "It's still a choice. Right now you don't have that choice."
Jim Lanzone, chief executive of IAC/InterActiveCorp's search company Ask.com, spent Saturday's 10-hour flight from San Francisco to London reading magazines and Steve Martin's "Born Standing Up." He watched television shows on his iPod and has DVDs of "The Wire" ready for his return flight.
Lanzone doesn't mind that Internet access would cut into all that.
"If I had something on deadline, I'm not going to be able to relax anyway," he said. "I can enjoy DVDs, music and books more because I'll be able to get things off my mind."
But that's a false choice, said Deb Wenger, a Virginia Commonwealth University journalism professor who finished Martha Grimes' mystery novel "The Five Bells and Bladebone" during a recent trip to New York.
"The reality is that there's a certain luxury in being able, in a guilt-free way, to tell someone you're not available now. It will be, 'I'm not making myself available to you,"' Wenger said. "It's a different message that sometimes employers don't want to hear."
Tim Winship, editor at large for the travel Web site Smarter Travel, predicted those stacks of magazines and books people save for long flights will start piling up again.
"The net effect of bringing Internet access onto airplanes is that there will be less reading accomplished," Winship said. "The question is how much."
Steve Jones, an Internet studies expert at the University of Illinois at Chicago, said unconnected time already has been shrinking because of cell phones and other handheld devices with Internet access. Soon, Jones said, people will get a break only during takeoffs and landings, as required by law.
Many frequent fliers, though, are looking forward to such continual access.
Henry Harteveldt, a Forrester Research analyst who follows the travel industry, flew to New York on Monday simply to take Tuesday's inaugural JetBlue flight with e-mail access.
"I find this to be a godsend," Harteveldt said via e-mail from Flight 641 to San Francisco. "The ability to stay in touch with my office and clients on a six-hour transcon flight is terrific. I hate that sense of dread when I turn on my BlackBerry after landing and get a flood of e-mail. Now I can manage real time."