Changes to federal policy that guide flight refunds are being proposed by the Department of Transportation to provide more recourse for passengers when airlines cancel flights.

The agency will make a decision on the rule after a 90-day public comment period ends.

Pete Buttigieg, the transportation secretary, said in a statement on Wednesday that the proposal would protect the rights of travelers.

Airlines are supposed to reimburse passengers for flights that have been canceled or changed. Many air travelers don't know that they are entitled to refunds, instead of credits, for canceled flights, and carriers have been accused of exploiting that.

A six-hour delay for an international flight is defined as a three-hour delay for a domestic flight. The new rule would entitle passengers to full refunds for any switch in the departure or destination airport, the addition of a layover, or a change in aircraft that causes a significant upgrade in seat class. A bill with similar protections was introduced this week by several Democrats.

Over the past year the number of delays and canceled flights has increased, affecting thousands of passengers eager to travel after two years of restrictions and closed airports.

20 percent of flights on U.S. carriers have been delayed this year, which is 6 percent more than the previous two years. On high- travel weekends, airlines have canceled flights four times as often as they did last year.

Travelers who are stuck have complained about the process of getting refunds.

Jones said she was fed up with airlines altering flights without giving adequate compensation.

Ms. Jones was told by United Airlines that her layover at Newark Liberty International Airport would be different in September. When she looked at her itinerary, she discovered that the Newark-to-Dublin leg of the flight had been changed and no longer had premium economy seats. She was told by the airline that she could only get a credit if she tried to get a refund. The policy would change.

The proposed rule would clarify when airlines would have to issue refunds.

The Department of Transportation wants airlines that received federal assistance early in the Pandemic to give refunds to passengers if they can't fly because of a virus. All airlines would have to give travelers vouchers that don't expire when they can't fly for reasons related to the swine flu.

The proposed changes will be discussed in an online public meeting.