Southwest Airlines scrubbed thousands of flights again Tuesday in the aftermath of the massive winter storm that wrecked Christmas travel plans across the US, and the federal government said it would investigate why the company lagged so far behind other carriers.

A day after most US airlines had recovered from the storm, Southwest called off about 2,600 more flights on the East Coast by late afternoon. Those flights accounted for more than 80% of the 3,000 trips that got canceled nationwide Tuesday, according to tracking service FlightAware.

And the chaos seemed certain to continue. The airline also scrubbed 2,500 flights for Wednesday and nearly 1,400 for Thursday as it tried to restore order to its mangled schedule.

At airports with major Southwest operations, customers stood in long lines hoping to find a seat on another flight. They described waiting hours on hold for help, only to be cut off. Some tried to rent cars to get to their destinations sooner. Others found spots to sleep on the floor. Luggage piled up in huge heaps.

Conrad Stoll, a 66-year-old retired construction worker in Missouri, planned to fly from Kansas City to Los Angeles for his father's 90th birthday party until his Southwest flight was cancelled early Tuesday. He said he won't get to see his 88-year-old mother either.

"I went there in 2019, and she looked at me and said, I'm not going to see you again.'" Stoll said. "My sister has been taking care of them, and she's just like, They're really losing it really quick.'"

Stoll hopes to get another chance to see his parents in the spring, when the weather is warmer.

In a video that Southwest posted late Tuesday, CEO Robert Jordan said Southwest would operate a reduced schedule for several days but hoped to be "back on track before next week."

Jordan blamed the winter storm for snarling the airline's "highly complex" network. He said Southwest's tools for recovering from disruptions work "99% of the time, but clearly we need to double down" on upgrading systems to avoid a repeat of this week.

"We have some real work to do in making this right," said Jordan, a 34-year Southwest veteran who became CEO in February. "For now, I want you to know that we are committed to that."

The problems began over the weekend and snowballed Monday, when Southwest called off more than 70 per cent of its flights.

That was after the worst of the storm had passed. The airline said many pilots and flight attendants were out of position to work their flights. Leaders of unions representing Southwest pilots and flight attendants blamed antiquated crew-scheduling software and criticized company management.

Casey Murray, president of the Southwest Airlines Pilots Association, said the airline failed to fix problems that caused a similar meltdown in October 2021.

"There is a lot of frustration because this is so preventable,” Murray said. “The airline cannot connect crews to airplanes. The airline didn't even know where pilots were at."

Murray said managers resorted this week to asking pilots at some airports to report to a central location, where they wrote down the names of pilots who were present and forwarded the lists to headquarters.

Lyn Montgomery, president of the Transport Workers Union representing Southwest flight attendants, said she and other labor leaders have repeatedly told management that the airline's scheduling technology is not good enough.

?"This has been something we have seen coming," she said. “This is a very catastrophic event."

The airline is now drawing unwanted attention from Washington.

Transportation Secretary Pete Buttigieg, who has criticized airlines for previous disruptions, said his agency would examine the causes of Southwest's widespread cancellations and whether the airline was meeting its legal obligations to stranded customers.?

"While we all understand that you can't control the weather, this has clearly crossed the line from what is an uncontrollable weather situation to something that is the airline's direct responsibility," Buttigieg told "NBC Nightly News". He said Southwest should at least pay cash refunds for cancelled flights and cover stranded passengers' hotel and meal costs.

?In Congress, the Senate Commerce Committee also promised an investigation. Two Senate Democrats called on Southwest to provide "significant" compensation for stranded travelers, saying that the airline has the money because it plans to pay $428 million in dividends next month.

Bryce Burger and his family were supposed to be on a cruise to Mexico departing from San Diego on Dec. 24, but their flight from Denver was canceled without warning. The flight was rebooked through Burbank, California, but that flight was canceled while they sat at the gate.

"It's horrible," Burger said Tuesday by phone from Salt Lake City, where the family decided to drive after giving up the cruise.

The family's luggage is still at the Denver airport, and Burger doesn't know if he can get a refund for the cruise because the flight to California was booked separately.

The size and severity of the storm created havoc for many airlines, although the largest number of cancelled flights Tuesday were at airports where Southwest is a major carrier, including Denver, Chicago Midway, Las Vegas, Baltimore and Dallas.

Spirit Airlines and Alaska Airlines both cancelled about 10 per cent of their flights, with much smaller cancellation percentages at American, Delta, United and JetBlue.

Kristie Smiley planned to return home to Los Angeles until Southwest canceled her Tuesday flight, so she waited at the Kansas City airport for her mother to pick her up. Southwest can't put her on another plane until Sunday, New Year's Day.?

Smiley said the airline kept blaming the weather after the storm passed and didn't tell passengers why planes couldn't take off.

"They like acted like (Tuesday's flight) was going to go until they started saying, 'Oh, five more minutes. Oh, 10 more minutes.' I'm not sure what's up with them. It seems a little off," she said.

Danielle Zanin vowed never to fly Southwest again after it took four days, several cancelled flights and sleeping in the airport before she, her husband and their two young children got home to Illinois from Albuquerque, New Mexico. They made stops at airports in Denver and Phoenix and reached Chicago only after ditching Southwest and paying USD 1,400 for four one-way tickets on American Airlines.

"I remember saying, 'Oh my God, we're getting on a plane!' I was honestly shocked because I thought we were stuck in airports forever," she said.

Zanin plans to ask Southwest to be reimbursed for part of their original tickets plus the new ones on American, and extra spending on rental cars, parking, an Uber ride and food — about $2,000 in all.

?"I don't have good faith that they will do much of anything," she said. (AP) ?NSD

?Military police enforce driving ban in snow-stricken Buffalo

State and military police were sent Tuesday to keep people off Buffalo's snow-choked roads, and officials kept counting fatalities three days after western New York's deadliest storm in at least two generations.

Amid some signs of progress — suburban roads and most major highways in the area reopened — County Executive Mark Poloncarz warned that police would be stationed at entrances to Buffalo and at major intersections to enforce a ban on driving within New York's second-most populous city.

“Too many people are ignoring the ban,” Poloncarz, a Democrat, said at a news conference.

Officials said more than 30 people had died in the region, including seven storm-related deaths that Buffalo Mayor Byron Brown's office announced Tuesday.?

The toll surpasses that of the historic Blizzard of 1977, blamed for killing as many as 29 people in a region known for harsh winter weather.

The National Weather Service predicted that as much as 2 inches (2.5 to 5 centimeters) more snow could fall Tuesday in Erie County, which includes Buffalo and its 275,000 residents.?

County Emergency Services Commissioner Dan Neaverth Jr. said officials also were somewhat concerned about the potential for flooding later in the week, when the weather is projected to warm and start melting the snow.

The rest of the United States also was reeling from the ferocious winter storm, with at least an additional two dozen deaths reported in other parts of the country, and power outages in communities from Maine to Washington state.

On the Rosebud Sioux Tribe's reservation in South Dakota, there were plans to use snowmobiles Tuesday to reach residents after food boxes were delivered by helicopter and trucks over the weekend, the tribe said.

In Buffalo, the dead were found in cars, homes and snowbanks.?

Some died while shovelling snow, others when emergency crews could not respond in time to medical crises.?

Poloncarz called the blizzard “the worst storm probably in our lifetime,” even for an area known for heavy snow.

The winter blast stranded some people in cars for days, shuttered the city's airport and left some residents shivering without heat.?

More than 4,000 homes and businesses were still without power late Tuesday morning.

Trisha LoGrasso and her family were still huddled around a space heater in a makeshift hut in her Buffalo living room Monday.?

She was without heat because of a gas leak, the temperature inside the home was 42 degrees (5.5 Celsius), and burst pipes left her with no running water.

“I've lived here my whole life, and this is the worst storm I've ever seen,” said LoGrasso, 48.

President Joe Biden offered federal assistance Monday to New York, allowing for reimbursement of some storm-relief efforts. Gov. Kathy Hochul toured the aftermath in Buffalo, her hometown, and called the blizzard “one for the ages.”?

Almost every fire truck in the city became stranded Saturday, she said.

Hochul, a Democrat, noted the storm came a little over a month after the region was inundated with another historic snowfall.?

Between the two storms, snowfall totals are not far off from the 95.4 inches (242 centimeters) the area normally sees in an entire winter season.

The National Weather Service said the snow total at the Buffalo Niagara International Airport stood at 49.2 inches (1.25 meters) at 10 a.m. Monday.?

Officials said the airport will be shut through Wednesday morning.

More than 2,900 domestic and international U.S. flights were canceled Tuesday as of about noon Eastern time, according to the tracking site FlightAware.

The U.S. Department of Transportation said it will look into flight cancellations by Southwest Airlines that left travellers stranded at airports across the country amid the winter storm.?

Many airlines were forced to cancel flights, but Southwest was by far the leader.?