Airline staff spread thin by a resurgence of coronavirus along with snowy weather meant thousands of grounded travelers across the country over the holiday weekend. But ambiguous federal guidelines on compensation for canceled or delayed flights may leave travelers up in the air.

As of Monday, over 3,000 U.S. flights were halted and nearly 7,428 delayed, according to online tracking service FlightAware. During New Year's weekend, approximately 5,400 U.S. flights were canceled.

With parts of the eastern U.S. expected to see up to 12 inches of snow, the Reagan Washington National Airport in Washington D.C. saw the most disruption on Monday, with 88 percent of its outgoing flights and 77 percent of its incoming flights canceled, according to FlightAware.

Air Travelers Wait For Bags
Airline passengers wait for bags to arrive from a carousel at the Harry Reid International Airport in Las Vegas on Sunday. Many travelers had chaotic journeys with thousands of flights cancelled because of bad weather or airline staffing problems caused by a surge of COVID cases.Getty/Patrick T. Fallon/AFP

The U.S. Department of Transportation's website states that passengers are entitled to refunds for canceled flights "regardless of the reason, and the passenger chooses not to travel." The same goes for when an airline makes a "significant schedule change" or "significantly delays."

However, the department's policy is open-ended and doesn't define "significant delay." Whether a passenger is entitled to a refund depends on the length of the delay, the flight and "particular circumstances," according to the department.

"DOT determines whether you are entitled to a refund following a significant delay on a case-by-case basis," according to the department's website.

The department last April issued a notice "that passengers should be refunded promptly when their scheduled flights are canceled or significantly delayed." Noting the COVID pandemic's severe disruption on travel, the notice said the department had received a rising number of complaints from passengers who said they'd been denied refunds for canceled or significantly delayed flights.

A report issued last month by consumer advocacy group U.S. PIRG Education Fund found that airline refunds were the largest source of consumer complaints, generating 107,781 between April 2020 through August 2021.

Despite the rise in complaints, Charlie Leocha, president of advocacy Travelers United, faulted the Department of Transportation in a blog post last month for not taking a more aggressive approach to airlines over refunds. He called on the department to issue uniform refund rules for all airlines.

"Today, each airline has its own rules and regulations," he said.

Airlines contacted by Newsweek did not respond with specific numbers on how many refunds or other compensation they've offered to passengers in recent days.

Southwest Airlines saw over half its flights disrupted as of Monday night, the most of any airline, according to FlightAware data. The carrier saw 637 flights canceled and 1,513 delayed.

Southwest says online it will give passengers their money back for refundable tickets if they cancel more than 10 minutes before its scheduled departure.

Another Southwest policy says it will help passengers with delayed or canceled flights find a discounted hotel near the airport if the "cause of your inconvenience is not within our means of control."

Delta Air Lines, which saw 4 percent of its flights canceled and nearly a quarter delayed as of Monday evening, says in its policy that it will give passengers their money back for fully refundable tickets.

However, the policy says most tickets issued by Delta are nonrefundable, and the airline "may permit" a portion of an unused non-refundable ticket to be used for future travel.

Delta will also give passengers a hotel voucher for one night if the delay occurs between 10 p.m. and 6 a.m. That's if overnight accommodations are available at a hotel contracted with Delta, the policy states.

"Delta people are continuing to work together around the clock to reroute and substitute aircraft and crews to get customers where they need to be as quickly and safely as possible," Delta spokeswoman Natalia Arenas Gallo told Newsweek in an email. "When that's not possible, Delta Reservations specialists are coordinating with our Operations and Customer Care Center to get those impacted on the next available flight."

The airline expects to cancel 200 flights daily between Tuesday and Wednesday because of winter weather in Seattle, Minneapolis and the Mid-Atlantic.