With public frustration rising after a string of highly publicized weather-related airline delays, air carriers are bracing for Congress — led for the first time in 12 years by a pro-consumer Democratic majority — to enact new customer service regulations.

Lawmakers in both chambers are offering similar but distinct bills that would crack down on delays and require better service for travelers when planes are grounded. The airline industry opposes new Congressional regulation, with carriers vowing to take their own steps to improve service.

Legislation by Sen. Barbara Boxer (D-Calif.), S.678, would require airlines to give passengers the opportunity to deplane if a flight was delayed for more than three hours. Passengers would be allowed to deplane once every three hours, unless the pilot determines that the flight will leave within 30 minutes after the delay or if doing so will jeopardize safety or security.

Boxer’s measure, introduced last Saturday, likely will be referred to the Senate Commerce, Science and Transportation subcommittee on aviation, operations, safety and security, on which she sits.

Under the measure, airlines would be required to institute such policies within 60 days of enactment of the bill. Boxer’s bill also would allow the Transportation Secretary to create additional regulations for deplaning if service does not improve.

“Occasional delays may be unavoidable, but no one should be held hostage on an airplane for hours without food, safe drinking water or functioning restrooms,” Boxer said in a statement.

In the House, Rep. Mike Thompson (D-Calif.) plans to introduce a broader bill that, in addition to allowing passengers to deplane after being on the ground for three hours, also would require airlines to draft and display a passenger bill of rights.

Thompson has taken up the issue in response to one of his constituents, Kate Hanni, who launched a drive for a passenger bill of rights after she was stranded in Texas on a flight operated by an affiliate of American Airlines on Dec. 29.

Hanni and other airline industry watchdogs want a passenger bill of rights to cap the time any delayed flight can sit on the tarmac without letting passengers get off. They also want the bill to specify compensation when airlines fail to deliver services as promised.

Thompson’s bill also would require frequent updates about the cause and timing of delays as well as disclosure of information on chronically delayed flights or canceled flights at the time of ticket purchase. In addition, the measure would require airlines to make every effort to return checked bags to customers within 24 hours of a flight.

Separately, Rep. Steve Cohen (D-Tenn.) is proposing legislation that would address deplaning and access to food, water and sanitary bathroom facilities. Cohen’s staff says they currently are working out language but declined to provide further details.

Air Transport Association of America President and Chief Executive Officer James May opposes new legislation, arguing that government standards will be inflexible and could backfire.

“We’re quite willing to discuss with Congress, but we are concerned that if there’s any federal law that they won’t be one-size-fits-all,” ATA spokeswoman Elizabeth Machalek said.

In an effort to institute its own regulations, and to bolster the company’s reputation in the wake of a major public relations crisis, JetBlue announced a “Customer Bill of Rights” on Tuesday. The move comes a week after an ice storm forced some passengers to sit on JetBlue planes for 10 hours and led to nearly 1,100 flight cancellations.

JetBlue will offer refunds and rebates for passengers delayed on inbound and outbound flights. It does not include provisions to deplane passengers in the event of delays less than five hours, nor does it offer compensation for delays because of weather, air traffic control, crew shortages or maintenance problems.

David Neeleman, JetBlue founder and CEO added during a conference call this week, “If Congress dictates something that says in three hours everyone has to come off a [delayed] plane that would be doing a disservice to our customers.”

According to the plan, JetBlue will either refund customers the cost of canceled flights or allow them to rebook flights at no additional cost. Customers experiencing departure delays of one to two hours would receive a $25 voucher for future travel. Those on flights delayed more than six hours would receive a voucher equivalent to the round-trip cost of the ticket.

Passengers on departing flights waiting on the tarmac will receive $100 off a future flight after three hours, a round-trip ticket after four hours, and the plane will return to the gate after five hours. Passengers may request a full refund if a flight is canceled within 12 hours of its departure time.

In 1999, Sen. John McCain (R-Ariz.), who served on the Senate Commerce, Science and Transportation Committee, introduced legislation that would have required airlines to provide pricing information flights and warnings about frequently canceled or delayed flights. McCain eventually stopped trying to enact legislation after the airline industry promised to institute its own customer service regulations.

In December 1999, airlines represented by ATA, rolled out a 12-point customer service plan that called for notification of known delays, cancellations and diversions; timely baggage delivery; and improved handling of ”bumped” passengers.

In 2001, the Transportation Department’s inspector general issued a report evaluating whether those efforts had succeeded. The report said that while ATA’s member airlines had made significant strides in implementing the recommendations, they didn’t address such core issues as customer notification of flights that are consistently delayed or canceled at time of booking.