ReutersJets at Reagan National Airport outside Washington.

New federal rules giving consumers more information and flexibility when they book air travel took effect this week.

Travelers, for instance, can now change or cancel a reservation within 24 hours and receive a full refund without penalty. The rule applies only if the reservation was booked at least a week in advance of the flight’s departure.

Some airlines have previously offered such cancellation privileges, depending on circumstances of the booking. But the new Department of Transportation rules apply across the industry.

The new rules also mean that airfare advertisements must clearly indicate the full price of a ticket, including mandatory taxes and government fees, and that airlines must clearly disclose baggage handling fees in online bookings.

Some airlines are contesting the new advertising rules, however. Visitors to Spirit Airlines’ Web site, for instance, now see a message stating: “WARNING. New government regulations require us to hide taxes in your fares.” Spirit is known for advertising $9 fares, then charging additional fees, including for checked and carry-on bags, advance seat assignments and online bookings.

In response, Senator Barbara Boxer, Democrat of California, criticized Spirit for trying to “deceive” the public.  “I urge you to immediately send a clarifying e-mail to your customers and remove the misleading information from your Web site,” she said in a letter to the airline’s chief executive, which was released to the media by her office.

Under the new rules, airlines must also “promptly” notify travelers of flight delays of more than 30 minutes.

More details are available on the Transportation Department’s Web site under “Frequently Asked Questions to Rule #2.”

Do you think the new rules will make it easier for you to accurately plan the cost of your travel?