The U.S. government is adding new protections for travelers when airlines lose their bags, bump them off flights or hold them on the runway for hours.
The airlines will also have to more clearly disclose the fees they charge.
Consumer advocates say the wide-ranging regulations announced Wednesday would improve the flying experience. Still, they wanted regulators to get even tougher on bag fees and make it easier to sue airlines over shoddy service.
Beginning in late August, passengers who pay $15 or more to check luggage will get a refund if their bag is lost. They'll also be entitled to more money _ up to $1,330 _ if they're bumped from a flight. Airlines will have to include government taxes and fees in advertised prices.
Delayed international flights won't be allowed to sit on the tarmac for more than four hours, an extension of a year-old rule for domestic flights that greatly reduced 3-hour delays.
Some advocates for the airline industry complained that the regulations could raise costs at a time when high fuel prices are threatening the airlines' bottom lines, but the CEO of American Airlines said he didn't see anything particularly alarming in the provisions.
Transportation Secretary Ray LaHood said the new regulations ensure that airlines treat travelers fairly.
"It's just common sense that if an airline loses your bag or you get bumped from a flight because it was oversold, you should be reimbursed," LaHood said.
Consumer advocates were generally pleased but suggested more could have been done for passengers.
Kate Hanni of FlyersRights.org said airlines should refund baggage fees when bags are late, not just when they're lost. And she favored a 3-hour holding limit on international flights instead of four.
"But overall we're winning," Hanni said, and the new rule includes "a lot of good stuff, a lot of little things that will make people feel better about traveling."
Others said the verdict was mixed.
"These are all baby steps and they're good, but there's more that can be done without bringing the airline industry to its knees," said George Hobica of airfarewatchdog.com.
Passengers bumped off oversold flights will be entitled to greater compensation _ up to $650 or $1,330, depending on how long a passenger waits for a makeup flight. The limits are currently $400 or $800.
Hobica said that's not enough compensation for delaying passengers' vacations or causing them to miss cruises and weddings. He said airlines should also be required to provide alternate transportation if they cancel a flight other than for reasons beyond their control, such as bad weather.
Mark Pestronk, a Washington lawyer who advises travel agents, called the rule "a big disappointment" because regulators dropped a proposal to require that airlines include their customer-service promises in legal contracts with passengers. He said that means consumers can't sue an airline that fails to live up to its promises; they can only file a complaint with the government.
Airlines said they're already doing many of the things the Transportation Department wants, including disclosing fees and telling passengers about developing delays. They pointed to government statistics, which show fewer bags are being mishandled and fewer passengers being bumped from oversold flights.
Some consultants said the 4-hour limit on tarmac delays for international flights would increase cancelations, and could leave stranded passengers waiting days for a seat on another flight.
Regulators were persuaded to adopt the 4-hour rule, however, after a late-December debacle in which several planes loaded with international travelers were stuck, some for more than 10 hours, on snowy runways at New York's JFK Airport. In the future, those airlines could face fines of up to $27,500 per passenger _ more than $10 million for a heavily loaded superjumbo jet like an Airbus A380 _ although the government has never imposed anything close to the maximum.
American Airlines CEO Gerard Arpey said his airline had adapted to last year's deadline on domestic flights and could handle the new one on international flights.
Darryl Jenkins, a consultant who has conducted tarmac-delay studies for the airlines, said airlines often send planes back to the gate long before the time limit to avoid any chance of a fine. So, they comply with the rule but cancel more flights, he said.
Jenkins also criticized the timing of new regulations, coming as airlines struggle to make a profit.
"They are making changes that will raise costs at a time when labor is going up, jet fuel is going up," Jenkins said. "The last thing you need is an exogenous shot from your own government."
Coincidentally, on Wednesday the parent of American Airlines reported a $346 million first-quarter loss.
How much more the new rules will cost carriers remains to be seen. Airlines are already required to compensate passengers for the value of lost bags, regardless of whether a fee was paid to check them. Last year, airlines mishandled 2 million bags, although that includes damaged and delayed ones.
As for bumping, airlines bumped 65,000 passengers last year and another 681,000 took voluntary offers to give up their seats. Still, that's a tiny fraction of 1 percent of all travelers. The higher limits could give savvy travelers leverage to cut a better deal for their seats after gate agents ask for volunteers.
The new rule also requires airlines to prominently disclose on their websites all potential fees _ for checking bags, changing reservations, upgrading seats, and so on.
In the most recent 12-month period for which government figures are available, the airlines made $7.9 billion from fees for checked baggage, reservations changes and other services.
Airlines will also have to include taxes and government-imposed fees in the fares that they advertise. Airlines had argued that car dealers and other businesses don't have to do that.
But in a setback for travel agents, the government declined at least temporarily to force airlines to clearly disclose all fees in their electronic connections with agents.