Desperate passengers camped out in airports have been a reliable subject for news broadcasts this year, with cameras panning from teary travelers to close-ups of the word "CANCELED" on flight status displays.

The storms and strikes that cause such scenarios are nothing new, but this year many passengers have been surprised by how little airlines are doing for customers when a flight is canceled. In the scramble to be rebooked, travelers are generally given two options: a refund for the unused portion of their ticket, or a seat on the airline's next available flight, which, now that there are fewer flights and many of those flights are full, could be days later.

Five or 10 years ago, airlines paid for hotels and meals more readily, but these days cash-strapped carriers largely try to avoid picking up such charges, even when the cancellation is their fault. Bill Mosley, a spokesman for the Department of Transportation, said carriers are legally obligated to fulfill any promises made in their contract of carriage, the lengthy document that governs ticket purchases. The legal jargon, however, is difficult to decipher, and the policies have become increasingly vague.

"The language in very subtle ways has gotten a bit mushier," said Bill McGee, a travel consultant to Consumers Union, the advocacy group. "In the past, if you saw language saying the airline 'will' do such-and-such, now you're seeing they 'may.'"

Here are some answers to questions that arise when a domestic flight is canceled.

When is a cancellation the airline's fault?

Hardly ever. Most carriers give themselves plenty of leeway to avoid taking responsibility for cancellations or delays. Basically, the only time an airline might take responsibility for a delay or cancellation is when there's a problem with the aircraft.

Another problem is that it is the airlines -- not an independent agency -- that determine the cause of a delay or cancellation; a common complaint is that carriers blame everything on bad weather. Of the 50,000 domestic flights canceled in the first four months of this year -- which accounts for 2.5 percent of scheduled flights, according to government statistics -- two-thirds were identified as weather-related.

Adam Martin was given the weather excuse in June when his American Airlines flight from Chicago to Washington required a mechanical fix. The flight was later delayed by thunderstorms and ultimately canceled, but Martin said he had to pay for a hotel and cab fare because the cancellation was coded as weather-related.

Andrea Huguely, a spokeswoman for American, said the ultimate reason for a cancellation prevails -- in this case, bad weather.

When does an airline have to pay for a hotel room?

If Martin's cancellation had been deemed American's fault, the airline's contract of carriage reads, "We will provide reasonable overnight accommodations, subject to availability." But airlines are often vague in defining when a cancellation is their fault, leaving plenty of wiggle room to avoid paying for a hotel.

Continental's contract says the airline will pay for one night's lodging (or at least a "lodging allowance") if a delay exceeds four hours between 10 p.m. and 6 a.m. -- except "when such interruption is due to circumstances outside Continental's control." According to Andrew Ferraro, a Continental spokesman, "required maintenance" is one situation that might cause the airline to cover lodging costs, although he and other airline representatives declined to outline when carriers would foot the bill or to say how often that happens.

Bottom line: Don't expect your hotel costs to be covered; legally, the airlines have created lots of loopholes to avoid picking up the bill. But don't hesitate to ask, because most airlines make these decisions on a case-by-case basis.

When does an airline have to put you on another carrier?

Airlines used to include a clause in their carriage contracts saying that if a delay or cancellation was their fault and their next flight was not for several hours, the airline would try to transfer passengers to another carrier with an earlier flight. Now most airlines say they "may" put you on another carrier, and some, like Southwest, simply say they won't.

What else can you do?

Always advocate for better treatment, because airline representatives acknowledge that they sometimes depart from their policies -- and some of those policies apply only "at the passenger's request."

"We empower our employees to make decisions if they find themselves in a situation with a customer that is unique or a special circumstance," said Susan Chana Elliott, a spokeswoman for Delta, confirming that having elite status or paying a higher fare can affect how you are accommodated after a cancellation.

Alexander Anolik, a San Francisco lawyer who specializes in travel law, advises customers to ask (politely) to be put on another carrier. If the cancellation is clearly the airline's fault and you cannot be rebooked in a reasonable time, he said, another option is to buy a new ticket and then sue the airline in small claims court to be reimbursed for the extra expense.

"If you're doing it to save an hour, the court may not think that's reasonable," Anolik said. "But if the airline says, 'Come back tomorrow,' that's not reasonable."