U.S. airline delays may worsen if airlines are forced to unload passengers from planes stuck on the ground, federal regulators were told Tuesday.

Unloading a plane in New York could strand waiting passengers in Europe, and Seattle travelers could be stuck because an unloading caused a plane to miss maintenance, said Gary Edwards, director of Delta Air Lines' operations control center.

"It just begins to snowball," Edwards told a federal task force. "We're very stringently against" any requirement that passengers be released after three hours.

The government panel wants to develop plans for handling passengers stuck aboard airliners during lengthy runway delays. The effort follows a call for a passengers' bill of rights after JetBlue Airways Corp. and American Airlines passengers were stranded on planes by storms in late 2006 and early 2007.

A U.S. Transportation Department inspector general's report Sept. 25 called for airlines to let passengers off planes following "extended" delays. That report also recommended a task force to develop model plans.

"We need to identify the service gaps," Transportation Secretary Mary Peters said in prepared remarks. "I want tangible results for travelers as quickly as possible."

About 1,600 flights were delayed on runways for more than three hours last year, up 24 percent from 2006, Peters said. Those delays have mounted as airline traffic grows and planes fly with more seats filled, giving carriers less flexibility to shift passengers in bad weather.

Peters proposed a rule Nov. 20 requiring carriers to set a maximum amount of time they will allow passengers to be stranded on the tarmac. That proposal, still pending, would allow passengers to sue carriers that fail to adhere to their plans.

Kate Hanni, who founded a passenger advocacy group after being stuck on an American flight for nine hours, wants Peters to go further. Regulators should require that passengers be given the option to get off stuck planes after three hours. Pilots would be able to extend that deadline an additional hour.

Passengers "feel like their needs are not being met," Hanni told the task force. "They don't want to board flights that aren't assured of taking off."

To emphasize her point, she played recordings of passengers who called her group's hotline while stuck on planes, as airline executives on the panel listened. "Children are in distress," reported one caller who said he had been stuck on a plane four hours at the time of his call.

Hanni, executive director of the Napa, Calif.-based Coalition for an Airline Passengers' Bill of Rights, held up an iPod media player that she said contained recordings of nearly 9,000 passenger calls.

The three-hour standard may not be good for consumers if airlines take planes back to the terminal, only to taxi out for another three-hour delay, task force Chairman Samuel Podberesky said.

"Theoretically, it could go on forever," said Podberesky, the Transportation Department's assistant general counsel for aviation enforcement. "It's still bad for consumers."

Scott Macey, who examined airline service plans for the inspector general's office, told the panel it "might be near to impossible" to create a single deplaning standard, because of differences in airport configuration and security concerns.

The inspector general's report was ordered by Peters after thousands of JetBlue and AMR Corp.'s American passengers were stranded on planes, some for up to 10 hours.

Peters appointed the panel, made up mostly of airline and airport executives, this month. She said she hopes to have plans in place before the year ends.