(CNN) — As beleaguered Southwest Airlines continues to sort out stranded passengers, uncollected baggage and out-of-position airplanes, US Transportation Secretary Pete Buttigieg has taken the airline to task.
He's pulling no punches, referring to the situation as a complete "meltdown" of the system.
Meanwhile, the airline's decision to enact "operational emergency" staffing procedures last week at the airport in Denver as a massive winter storm bore down hints at a tangle of factors contributing to the airline's operational crisis.
The emergency staffing procedures in Denver included requiring a note from a doctor to verify illness after an employee calls out sick, a Southwest spokesperson told CNN Wednesday.
The spokesperson could not say whether the staffing policy remains in place or when the special rules ended.
The Washington Post cites a Southwest memo related to the operational emergency, dated December 21, in which the airline's vice president for ground operations declared the condition because of an "unusually high number of absences" of Denver-based ramp employees, including sick calls and personal days for afternoon and evening shifts.
The operational emergency -- experienced only at Denver, according to the company -- is distinct from the issue the company says is to blame for the cascade of cancellations.
Denver International Airport has announced plans to conduct after-action reviews with the airport's three major carriers -- Frontier, Southwest and United -- to learn from the disruptions while the situation is still fresh.
A ray of hope?
Meanwhile, an official for the union representing Southwest pilots said they expect to have their flight schedules almost back to normal by the end of the work week.
Mike Santoro, vice president of the Southwest Airlines Pilots Association, told CNN's Wolf Blitzer on Wednesday that they have been hearing that the airline is planning for a "mostly full schedule come Friday."
"The weather, you know, was a big event that triggered it, although that's no excuse for the lack of scheduling IT infrastructure which really caused the problem," Santoro said.
The union official said Southwest's scheduling infrastructure usually works well, but added this is not the first time they have seen a meltdown causing delays. "When you have these big weather events, it always seems to crash," said Santoro.
As of 9:15 p.m. ET Wednesday, Southwest had canceled only 39 flights for Friday (compared to almost 2,350 for Thursday), according to flight tracking website FlightAware.
Latest flight cancellation stats
Of the 2,902 cancellations already logged for Wednesday flights departing within, to or out of the United States as of 9:15 p.m. ET, some 2,509 of them are operated by Southwest, according to FlightAware. That is 86% of all canceled flights in the United States; all the other airlines together account for the remaining 14%.
In all, Southwest has canceled about 15,700 flights since winter weather began disrupting air travel on December 22. That figure includes almost 2,350 flights already canceled for Thursday.
There were 3,211 flights within, into or out of the United States that were canceled on Tuesday, according to FlightAware. Southwest accounted for 2,694 of those canceled flights -- a stunning 84% of all canceled flights in the United States.
Denver International Airport is leading the way in the number of cancellations Wednesday, with significant cancellations also at Chicago Midway, Dallas Love Field, Las Vegas Harry Reid and Nashville International airports, among others.
The airline has struggled to unwind itself from the cancellations that began with the winter storm. Union leaders say software and manual processes are used to reassign flight crews, who for safety reasons are limited in the number of hours they may work.
Southwest spokesperson Chris Perry told CNN the airline is not experiencing an issue with employees not showing up for work.
"We have not had staffing issues at any station across our operation and commend our People for the valiant work they are doing," Perry said.
This is now a Southwest problem
Other US airlines that are flying in the same weather conditions have since recovered from the storm disruptions.
In fact, American Airlines and United Airlines have capped prices on some routes served by Southwest Airlines to make their flights more accessible to stranded passengers.
Southwest does not have interline agreements with other carriers that would allow its agents to rebook passengers on a different airline, leaving travelers in charge of exploring other options.
Southwest plans to fly a reduced schedule over the next few days to reposition crew and planes, airline CEO Bob Jordan said in a video released by the airline late Tuesday.
"We're optimistic to be back on track before next week," he said.
Buttigieg says he spoke directly to Jordan on Tuesday about the thousands of flights that have been canceled this week.
"Their system really has completely melted down," Buttigieg told Blitzer on Tuesday.
"I made clear that our department will be holding them accountable for their responsibilities to customers, both to get them through this situation and to make sure that this can't happen again."
Those responsibilities include providing meal vouchers and hotel accommodations for passengers whose flights were disrupted "as a result of Southwest's decisions and actions," a Department of Transportation spokesperson said Tuesday.
US airlines are also required to provide cash refunds to passengers whose flights were canceled and opted not to travel, the DOT said.
Southwest has blamed the travel disaster on several factors, including winter storm delays, aggressive flight scheduling and outdated infrastructure.
"From what I can tell, Southwest is unable to locate even where their own crews are, let alone their own passengers, let alone baggage," said Buttigieg, adding that he also spoke with leaders of the airline's unions representing flight attendants and pilots.
The secretary said he told CEO Jordan that he expects Southwest to proactively offer refunds and expense reimbursement to affected passengers without them having to ask.
Buttigieg told CNN the Department of Transportation is prepared to pursue fines against Southwest if there is evidence that the company has failed to meet its legal obligations, but he added that the department will be taking a closer look at consistent customer service problems at the airline.
"While all of the other parts of the aviation system have been moving toward recovery and getting better each day, it's actually been moving the opposite direction with this airline," said Buttigieg.
"You've got a company here that's got a lot of cleaning up to do," he said.
Is there anything passengers can do?
"First things first, travelers who are still stuck waiting on Southwest and need to get somewhere should try to book a flight with another airline as soon as possible ... right now, really," said Kyle Potter, executive editor at the travel advice website Thrifty Traveler, in an email to CNN Travel on Tuesday.
"Every airline in the country is jam-packed right now, so your odds of even finding a seat -- let alone at an even halfway decent price -- get smaller by the hour," Potter said.
Phil Dengler, co-founder of travel advice site The Vacationer, said stranded Southwest passengers should get their heads out of the clouds.
"I recommend searching for alternative forms of transportation. While Southwest may get its act together over the next few days, I would not take the risk," Dengler said. "It is legally required to provide you with a full cash refund if your flight was canceled, so it is in your best interest to have a solid backup plan."
If you're booked on Southwest next week
Southwest says this will be sorted by next week. So what should people booked with Southwest a week from now do?
"You need a backup plan if you are booked to fly on Southwest next week. While the airline claims the issues will be sorted out next week, there is no guarantee of that happening," said Dengler.
"Search for train tickets and look up car rental prices if that is possible for your destination. Most car rental companies allow you to cancel your reservation at any time for no reason, so it does not hurt to book a refundable rental."
Another option: Search for refundable airline tickets.
"While it will be more expensive ... If your Southwest flight is canceled, you will have a backup ticket with the other airline. You will also be entitled to a full cash refund from Southwest because of the cancellation.
If your Southwest flight is not canceled or significantly delayed, you can cancel your refundable ticket with the alternate airline," Dengler said.
Speaking to CNN on Tuesday, the vice president of the Southwest Airlines Pilots Association, Capt. Mike Santoro, said the problems facing Southwest were the worst disruptions he'd experienced in 16 years at the airline.
He described last week's storm as a catalyst that helped trigger major technical issues.
"What went wrong is that our IT infrastructure for scheduling software is vastly outdated," he said. "It can't handle the number of pilots, flight attendants that we have in the system, with our complex route network.
"We don't have the normal hub the other major airlines do. We fly a point-to-point network, which can put our crews in the wrong places, without airplanes."
CNN's Gregory Wallace, Andy Rose, Andi Babineau, Adrienne Broaddus, Dave Alsap, Nick Valencia, David Goldman, Leslie Perrot, Carlos Suarez and Ross Levitt contributed to this story.