In-flight Wi-Fi, the next big-fee income generator for airlines, is available so far on 711 commercial aircraft, and the number is growing. Eight airlines, so far, have deals with technology provider Aircell to offer its Gogo in-flight service for $4.95 per flight segment and up, based on the length of the trip.

The service lets passengers with laptops and smart phones surf the Web, e-mail, and access corporate networks.

“It’s going to become universal,” said Jay Sorenson, president of the Wisconsin-based airline consulting firm IdeaWorks. “Wireless connection has become imperative for a lot of people.”

Travelers, at least so far, are more accepting of Wi-Fi fees than they are of the bag-check fees that have been squeezing them. “People recognize the technological complexity of offering decent Wi-Fi service at 30,000 feet,” Sorenson said.

All of the big network carriers have started retrofitting aircraft to offer it, said Aircell spokeswoman Jessica Anselmi.