WASHINGTON -- After being stuck for 11 hours on a parked airplane during a snow and ice storm, JetBlue passengers found out there's nothing they can do about it. There are no government regulations limiting the time an airline can keep passengers on grounded aircraft.

The airlines' voluntary code of conduct simply says that during such extraordinary delays, they will make "reasonable efforts" to meet passenger needs for food, water, restroom facilities and medical assistance.

Airlines have blocked attempts to set minimum legal standards for customer service by agreeing to a voluntary code of conduct that they have not always followed.

On Wednesday, hundreds of JetBlue passengers were stuck for as long as 11 hours in parked jets at John F. Kennedy International Airport during a snow and ice storm. Reasons included congestion, frozen equipment and an effort to keep planes ready to go in case the weather broke, said JetBlue spokesman Bryan Baldwin.

The airline acknowledged that it hesitated nearly five hours before calling for a fleet of buses to unload at least seven jets that spent the day sitting on runways because of the weather and gate congestion.

The airline later apologized, calling the delays unacceptable, and said it would offer refunds and free flights to passengers delayed onboard a plane for more than three hours.

Sean Corrinet of Salem, Mass., spent almost nine hours aboard a JetBlue flight for Cancun, Mexico, that never got off the ground. "It was like -- what's the name of that prison in Vietnam where they held [former POW and Arizona Republican Sen. John] McCain? The Hanoi Hilton," Mr. Corrinet said.

He said the crew passed out bags of chips, the only available food, and periodically cracked the hatch to let in fresh, cool air.

Then yesterday, nearly 100 passengers spent several hours aboard another JetBlue plane at Pittsburgh International Airport because of weather-related brake problems.

The pilot of Flight 1050 to New York City stopped on the taxiway about 8:20 a.m. after reporting that its brakes were frozen and inoperative, airline and airport officials said. Crews de-iced the plane, but that did not remedy the problem, Allegheny County Airport Authority spokeswoman JoAnn Jenny said.

Passengers aboard the plane, which had been scheduled to leave at 7 a.m., disembarked about noon, JetBlue spokeswoman Alison Eshelman said.

A similar incident occurred Dec. 30, when American Airlines and American Eagle diverted 121 flights bound for Dallas to other cities because of thunderstorms. About 5,000 passengers were left sitting on parked aircraft, some for eight hours. The Dec. 30 incidents prompted American to say it would put a four-hour limit for keeping passengers aboard grounded planes.

In the late 1990s, the nation's 14 largest airlines joined forces to block a drive by Congress to enact legal protections for passengers, changes sought after a series of flight cancellations and delays. Instead, the airlines agreed to an Airline Customer Service Commitment and incorporated it in their customer agreements, called "conditions of carriage," which are legally enforceable by the customer against the airline.

However, the airlines didn't agree to limit the amount of time they could keep people inside grounded planes.