WASHINGTON - Weather-related flight cancellations and delays that snarled US commercial air traffic over the holiday weekend dragged on through Monday, with Southwest Airlines accounting for the bulk of the lingering disruptions after a massive winter storm snarled airport operations around the country.

More than 3,800 US airline flights were cancelled on Monday, including 2,800 operated by Southwest, or nearly 70 per cent of the carrier’s total scheduled for the day, according to the flight tracking service FlightAware.

Delays were reported for more than 7,100 US flight departures and arrivals overall, with several hundred by Southwest.

“Challenges are impacting our customers and employees in a significant way that is unacceptable,” Southwest said in a statement, citing “consecutive days of extreme winter weather”.

The Dallas-based airline, one of the world’s largest low-cost carriers, said it anticipated the disruptions would continue in the days heading into the New Year holiday travel period at the end of the this week.

The US Transportation Department said late on Monday it would examine the large number of Southwest Airlines cancelled and delayed flights in recent days to determine if they were in the airline’s control, calling them “unacceptable”.

Commercial airline traffic has been upended since last week as an Arctic blast coupled with a massive winter storm dubbed Elliott took shape over the Midwest and swept over much of the United States in the lead-up to the Christmas holiday weekend.

The resulting surge in cancellations and delays, coupled with long lines and missing luggage at airports, spoiled wintertime vacation plans for countless US airline customers during one of the busiest travel periods of the year.

Mr Kyle Goeke, a 29-year-old Alaska Airlines customer, said he would be stuck in Seattle for days because the airline cancelled his flight, scheduled for early Monday, from Seattle to Missoula, and the next available flight was Wednesday.

He had travelled from Washington DC to Seattle late on Sunday and said he hadn’t slept at all overnight, as he was instead making arrangements for his stay in Seattle.

“Luckily, I have a friend here in this city to help me out, many others are just left by themselves,” he told Reuters.

Customers took to social media to express frustration and to try to get a response from airlines.

Mr David Sharp said on Twitter his Southwest Airlines flight from Denver to St. Louis was cancelled and the next flight was not available for another two days. He said he would rent a car and drive to his destination.

Voice actress Grey DeLisle tweeted to Southwest Airlines: “Flight 1824 from Nashville to Burbank was cancelled due to Elliot and we haven’t received any rebooking! The kids’ daddy has already missed Christmas now and his luggage is lost with medication in it! Customer Service line busy. Help!”

Southwest Airlines said on Monday it was facing a large number of calls from customers inquiring about their travels and that it was “doing its best” to get its network back to normal after the storm.

“My brothers Southwest Airlines flight out of Philly back to El Paso was cancelled today and the best they could do was out of Baltimore on Tuesday morning! Nothing anyone could do but so much travel insanity,” said another Twitter user named Alex Gervasi.

Some luggage at the baggage claim at William P. Hobby Airport in Houston was there for two days and some passengers could not locate their luggage, local media reported.

Ms Madeline Howard, who had not got her luggage, said on Twitter she had already been told by Southwest Airlines that the luggage was flying to a different airport despite her flight having been cancelled.

The massive winter storm wreaking havoc with travel has been blamed for at least 55 deaths in the United States since late last week, according to an NBC News tally. REUTERS