Southwest Airlines: Cancellation Continues; The days of relief are gone.

(CNN) — For passengers stuck with Southwest Airlines this week, the much-needed conclusion to the carrier’s woes is still days away.

U.S. Transportation Secretary Pete Buttigieg took the airline into action as the troubled airline continued to deal with stranded passengers, unclaimed baggage and grounded planes.

He referred to the situation as a complete “meltdown” of the system. And the airline’s decision last week to adopt “emergency” personnel handling procedures at Denver Airport as a major winter storm hints at several factors contributing to the airline’s labor crisis.

Emergency worker procedures in Denver include requesting a doctor’s note to confirm illness after an employee is sick, a Southwest spokeswoman told CNN on Wednesday.

A spokeswoman could not say whether the personnel policy would remain in place or when the special rules would end.

The operational emergency — which occurred only in Denver, according to the company — is separate from the case where the company is responsible for the cancellation.

Denver International Airport announced plans to conduct after-action reviews of the airport’s major carriers — Frontier, Southwest and United — to learn from the disruption while the situation is still fresh.

The widespread cancellations continued Wednesday afternoon.

Latest flight cancellation statistics

As of 3:20 p.m., 2,509 of the 2,860 cancellations recorded for Wednesday flights to or from the U.S. were handled by Southwest, according to flight tracking website FlightAware. That’s 88 percent of all canceled flights in the United States. All other airlines together account for the remaining 12 percent.

Southwest has canceled nearly 15,700 flights since winter weather began disrupting air travel on Dec. 22. This figure includes 2,350 canceled flights for Thursday.

The airline has struggled to extricate itself from cancellations triggered by winter storms. Software and manual procedures are used to assign flight crews, who are limited in their working hours for safety reasons.

Southwest spokesman Chris Perry told CNN the airline is not experiencing any problems with employees not showing up for work.

“We have not had a staffing issue at any of our sites and we thank our people for the heroic work they are doing,” Perry said.

This is the Southwest’s problem now.

Other US airlines flying in similar weather have recovered from the storm’s disruption.

Southwest does not have interline agreements with other carriers that allow its agents to rebook passengers on another airline, and travelers are responsible for exploring other options.

Denver International Airport led the way in cancellations Wednesday, with significant cancellations at Chicago Midway, Dallas Love Field, Las Vegas Harry Reid and Nashville International Airports, among others.

Southwest plans to fly a reduced schedule over the next few days to accommodate crew and aircraft relocations, the airline’s CEO, Bob Jordan, said in a video released late Tuesday.

“We hope to be back on track before next week,” he said.

Buttigieg said he spoke directly with Jordan on Tuesday about the thousands of canceled flights this week.

“Their system has completely melted down,” Buttigieg told CNN’s Wolf Blitzer on Tuesday.

“I’ve made it clear that our department will hold them accountable for their responsibility to their customers to get them through this situation and prevent this from happening again.”

Those responsibilities include providing meal vouchers and hotel accommodations to passengers whose flights have been disrupted, a Department of Transportation spokeswoman said Tuesday.

US airlines are required to provide refunds to passengers whose flights are canceled and who choose not to travel, according to DOT.

Tuesday at a glance

There were 3,211 canceled flights in the United States, both inbound and outbound, on Tuesday, FlightAware reported.

Southwest accounted for 2,694 of the canceled flights — a staggering 84 percent of all canceled flights in the United States.

As long-haul travelers tried to rebook or make connections at Southwest ticket counters at several U.S. airports on Tuesday, passengers struggled to reclaim their luggage at airports, Harry Reid of Chicago Midway International said in a statement. Las Vegas and William P. Hobby Airport in Houston.

Passenger Trisha Jones told CNN at the Atlanta airport that she and her partner had been traveling for five days trying to get home to Wichita, Kansas after disembarking in Fort Lauderdale, Florida.

After her flight was canceled, she stayed with relatives, then returned to Atlanta to catch a connecting flight.

“We were lucky, because we were in Fort Lauderdale — my family lives in the Tampa Bay area, so we were able to rent a car to see my family for Christmas,” Jones said. “We saw so many families sleeping upstairs and it breaks my heart.”

Buttigieg: ‘Lots of cleaning up to do’

Southwest blamed the travel disaster on a number of factors, including winter storm delays, aggressive flight schedules and outdated infrastructure.

“As far as I can tell, Southwest can’t even locate their own crew, let alone the passengers, let alone the baggage,” Buttigieg said, speaking with leaders of the airline’s unions representing flight attendants and pilots.

The secretary told CEO Jordan that Southwest expects to proactively issue refunds and reimbursements to affected passengers without asking.

Buttigieg told CNN that the Transportation Department is prepared to pursue penalties against Southwest if there is evidence that the company failed to meet its legal obligations, but added that the department will closely monitor a series of customer service problems at the airline.

“While other parts of the aviation system are recovering and improving every day, it’s really going in the opposite direction with this airline,” Buttigieg said.

“There is a lot of cleanliness in this company,” he said.

Southwest’s CEO apologized for the video

“We’re doing everything we can to get back to normal operations, and I’m really sorry,” Jordan said.

The airline said it had decided to “significantly reduce our flights” to accommodate a large number of aircraft and crew in dozens of cities “without space”.

While Jordan acknowledged problems with the company’s response, the statement indicated that he did not see major changes in Southwest’s response to the mass cancellations.

“Our disaster recovery tools serve us well 99% of the time, but we clearly need to improve our existing plans and systems for these extremes so that we never face what’s happening now.” Jordan said.

Is there anything passengers can do?

Southwest warned that this week’s cancellations and delays will continue for several more days.

So what should customers do?

“Every airline in the country is packed right now, so your chances of getting a seat — let alone half as good a price — diminish with time,” Potter said.

“Travelers in the thick of it should be sure to save all their receipts: other flights, rental cars, hotel nights, meals, anything,” Potter said.

“US Airlines’ main phone line is blocked with other passengers. Call the airline’s dozens of international offices to get quick access to an agent,” Scott Keys said. Those agents can handle U.S.-based locations, Keyes said.

Southwest: ‘Keep Your Receipts’

Southwest spokesman Jay McVeigh said Monday night at Houston’s William P. In a press release from Hobby Airport, the airline said it would do everything it could to fix the challenges faced by passengers: “To try and work with hotels, travel assistants, vans… rental cars, make sure these people get home as soon as possible.”

They have promised that customers who have checked out of the airport or who have made their own alternative arrangements will also be taken care of.

“If you’re already gone, take care of yourself, do what you need to do for your family, take care of your bills,” McVey said. “We’ll make sure they’re taken care of, that’s not the question.”

From a pilot’s point of view, what’s wrong?

He said last week’s storm helped trigger major technical issues.

“What’s wrong is that our IT infrastructure is too outdated to schedule software,” he said. The number of pilots we have in the system, the flight attendants, cannot be accommodated by our complex road network.

“We don’t have the regular hubs that other major airlines do. We fly a point-to-point network, which can put our crew in the wrong place without the planes.”

He added: “It’s disappointing for the pilots, flight attendants and especially our passengers. We’re tired of apologizing to the Southwest Airlines pilots. Our hearts go out to all passengers, they really do.”

CNN’s Gregory Wallace, Andy Rose, Andy Babineau, Adrian Broadus, Dave Allsap, Nick Valencia, David Goldman, Leslie Perot, Carlos Suarez and Ross Levitt contributed to this story.