What are travelers' rights?(Canceled flights)

With the July 4 holiday and the summer travel season looming, flight delays and cancellations--whether for bad weather or fear of terrorist attacks--become an immediate concern.

Canceled flights can be disruptive, not to mention unnerving, even though they are fairly rare. In February, the latest month for which data are available, the Department of Transportation reported that 1.7 percent of some 350,000 domestic flights were canceled for some reason. By contrast, nearly 21 percent of flights were delayed for some reason. Airport congestion, air-traffic-control delays, and the like caused most delays; bad weather and security concerns accounted for slightly more than 1 percent.

What can you do if your flight is canceled? Here are some guidelines:

General rules if you're grounded. The airlines we contacted say that their aim is to accommodate passengers on canceled flights as quickly as possible.

* The airline will automatically put you on its next available flight to your destination.

* If your carrier has no other flights or if all its flights are full, it will try to put you on another carrier traveling to the same destination at no additional charge.

If the cancellation is the airline's fault and you're stranded overnight. If there are no other flights available on any airlines to your destination on the day your flight is canceled, you'll have to stay overnight in your departure city. Airlines sometimes provide hotel accommodations to displaced passengers at no cost or at discounted rates, and they might also provide meal vouchers. Policies differ among the airlines.