New York ? Seat 17D is yapping endlessly on an Internet phone call. Seat 16F is flaming Seat 16D with expletive-laden chats. Seat 16E is too busy surfing porn sites to care. Seat 17C just wants to sleep.

Welcome to the promise of the Internet at 33,000 feet – and the questions of etiquette, openness and free speech that airlines and service providers will have to grapple with as they bring Internet access to the skies in the coming months.

“This gets into a ticklish area,” said Vint Cerf, one of the Internet’s chief inventors and generally a critic of network restrictions. “Airlines have to be sensitive to the fact that customers are (seated) close together and may be able to see each other’s PC screens. More to the point, young people are often aboard the plane.”

Technology providers and airlines are already making decisions. Some will block services like Internet phone calls altogether while others will put limits and install filters on content.

Panasonic Avionics Corp., a Matsushita Electric Industrial Co. unit testing airborne services on Australia’s Qantas Airways Ltd., is designing its high-speed Internet services to block sites on “an objectionable list,” including porn and violence, said David Bruner, executive director for corporate sales and marketing.

He said airlines based in more restrictive countries could choose to expand the list.

The company also is recommending that airlines permit Internet-based phone calls only on handsets with wireless Wi-Fi capabilities – the technology delivering access within the passenger cabin. Airlines, he said, also could block incoming calls – and the annoying ring tones they produce – or designate periods of quiet time.

Airlines have offered in-flight phone services before, but their high costs have limited their popularity. By contrast, Internet phone calls are free or cheap, particularly for passengers already paying for in-flight access to check e-mail or surf Web sites.