Canceled flights? Lost luggage? These are your rights as an air traveler this holiday season.

A record-breaking number of people are expected to fly this holiday season. The Transportation Security Administration (TSA) projects it will screen 18.3 million people during a six-day stretch on Thanksgiving week, including 2.8 million people on Tuesday, Nov. 26, 2.9 million on Wednesday, Nov. 27, and more than 3 million people on Sunday, Dec. 1.

With so many passengers passing through the nation's airports, there will invariably be travel disruptions. So what happens if your flight gets delayed or canceled, or your luggage gets lost?

Here's a quick guide to your rights as an air traveler.

When are you entitled to a flight refund?

This will be the first Thanksgiving since a new federal transportation policy went into effect earlier this year regulating how and when airlines provide refunds.

According to the Department of Transportation’s (DOT) new “Automatic Refund” rule, you're entitled to a refund if...

• Your flight is canceled and the airline does not rebook you or you do not accept rebooking.
  
  "You are entitled to a refund if the airline cancels a flight, regardless of the reason, and does not rebook you on a new flight or you do not proactively accept alternative compensation, such as a flight voucher or miles," the DOT explains. "If your flight is canceled and the airline offers rebooking or alternative compensation, but you do not accept these offers, you are entitled to a refund."

• Your flight is significantly changed and you do not accept the changed itinerary or any alternative compensation.
  
  "If your flight is significantly changed and you do not want to travel with the changed itinerary or a rebooked itinerary and you do not accept any other compensation offered in lieu of a refund, you are entitled to a refund," says the DOT.

Wait, what constitutes a ‘significant change’?

Per the new rule, a “significant change” occurs when...

• Your domestic flight departs or arrives more than three hours later or earlier than originally scheduled.
  

• Your international flight departs or arrives more than six hours later or earlier than originally scheduled.
  

• The origin or destination airport of your flight is changed.
  

• The number of flight connections is increased.
  

• If you are a person with a disability and the connections at different airports or flights on different planes are less accessible or accommodating than what you had originally booked.

What happens if an airline loses your luggage?

Airlines are required by law to compensate passengers if their bags are damaged, delayed or lost.

If your baggage is significantly delayed (that is, not delivered within 12 hours of a domestic flight arriving at the gate, or 30 hours for international flights) you are entitled to a refund for a checked bag fee, according to the DOT.

Once an airline determines that a bag is lost, the airline is responsible for compensating the passenger for the bag’s contents subject to maximum limits on liabilities ($3,800 per passenger for domestic flights). But how long it takes to declare a bag lost depends on the airline.

"Most airlines will declare a bag lost between five and 14 days after the flight," the DOT says, "but this can vary from one airline to another."

If your luggage is delayed, the agency advises that you file a mishandled baggage report as soon as possible.

• Also read: Flying this Thanksgiving? The TSA shares how to pack a plane-safe holiday meal.

What other refunds are you entitled to?

In addition to flight and luggage refunds, you're entitled to a refund for any extra services — such as Wi-Fi or in-flight entertainment — if you paid for the service, but it is unavailable or non-functional during your flight.

When are you not entitled to a refund?

You are not entitled to a refund if you decide to accept a rebooked flight or continue with a significantly changed itinerary.

OK, so how do you get a refund for a canceled flight?

The new DOT policy changed the way passengers get refunds. Previously, passengers were responsible for navigating airline policies to determine whether they are entitled to a refund and then explicitly request one. Under the new rules, airlines must automatically provide refunds without passengers having to explicitly request them.

In addition:

• Airlines and ticket agents must provide refunds in cash or in the form of original payment used to make the purchase, such as credit card or airline miles.

"Airlines may not substitute cash refunds owed to consumers with vouchers, travel credits or other forms of compensation unless the passenger affirmatively chooses to accept alternative compensation," the DOT says. (And if they do choose to accept, the voucher or credit must be valid for at least five years from the date it’s issued.)

• Your refund must be for the full price of your ticket, including all fees minus any portion of the flight itinerary already used (such as a connecting flight).
  

• Your refund must be issued in your original form of payment, whether that's cash, a credit card or airline miles. Airlines cannot substitute a cash refund with flight vouchers or travel credits, unless you choose to accept this as compensation. In this case, the travel voucher must be valid for at least five years from the date it was issued.
  

• If you used a credit card, airlines and ticket agents must issue a refund within seven days. For other forms of payment, a refund must be issued within 20 days.

What about travel to and from the airport?

Even if your flight gets canceled after you’ve arrived at the airport, airlines are not responsible for refunding the costs of getting there.

However, most U.S. airlines have committed to providing benefits such as overnight hotel stays or meal reimbursements for passengers during significant delays and cancellations that are caused by issues within the airline’s control. You can check which benefits different airlines provide at flightrights.gov.

How does travel insurance factor in?

Travel insurance covers all sorts of situations that are not typically covered by airlines or are out of their control, such as injury or illness. But they vary by price and policy, so it’s important to read the fine print.

What happens if your airline doesn’t offer you a prompt refund?

The DOT advises contacting the airline directly to ensure it gives you what is owed. If you are not satisfied, you can file a complaint with the DOT.

Are there apps that can help you navigate all of this?

Yes. Flight-tracking apps like FlightAware, Flighty and CheckMyTrip can alert you to delays and cancellations in real time. For help processing refund claims, AirHelp is one of the most popular and best-reviewed apps available.

And if you're truly stuck in an airport due to a delay, LoungeBuddy helps you locate nearby airport lounges to relax in while you wait for your flight.