Airline travelers headed on a weather delayed flight to South Korea wait in a slow-moving line at the Air France/KLM check in counter at Dulles International Airport. (Paul J. Richards/AFP/Getty Images)

At 9 a.m. Wednesday, officials at Dulles International Airport set an ambitious goal: Despite 81 / miles of runway covered in more than a foot of snow, they pledged to reopen to air traffic by noon.

Just a few hours earlier, about 6 a.m., airport officials had reluctantly announced that the runways would close. There was just too much snow. Officials were not pleased.

“We take pride in not closing the airport or the runways,” said duty manager William Hall.

But the storm that began Wednesday night and continued into early Thursday, proved to be too much. It dumped at least 12.6 inches of heavy, wet snow at Dulles. The runways and taxiways were a sea of white. It was the largest snowfall in the region since 2010’s “Snowmageddon” and the first time since then that the airport had to shut down all of its runways.

Winter Storm Pax, as this one has been dubbed, paralyzed travel at the nation’s major airports, and by Thursday afternoon, nearly 6,000 domestic and international flights across the country had been canceled, according to the flight-tracking Web site Flight­Aware.

The airport's central command center was buzzing with activity on Thursday as crews worked to clear more than a foot of snow from the airport's runways. (Lori Aratani/The Washington Post)

There were no flights in or out of Reagan National Airport for much of Thursday. Just over half a foot fell there, and crews found themselves struggling with where to put it all. Flights resumed just after 5 p.m., but officials warned that it could be days before the airport was back to normal.

At Baltimore-Washington International Marshall Airport, runways remained open, and a handful of flights were able to take off or land. But for the most part, the terminal was deserted.

Even Hall, a 30-year Dulles veteran who has seen storms big and small, said: “This was a good-sized storm. This storm kind of got the better of us because the fall rate was just too great to keep up.”

But Hall and others at Dulles were determined that the snow would not have the last word.

The closure set off a chain reaction.

Most airlines had already canceled domestic flights, but the question of what to do with international flights in the air and bound for Dulles loomed large.

An international flight coming in from South Africa was permitted to land just after 6 a.m., but a handful of other flights would have to be diverted.

Inside the airport operations center, a half-dozen staff members — operations technicians, airport duty managers, safety and security specialists, and administrative support staff — worked their stations.

Decisions came quickly. United Airlines opted to divert its Dubai flight to Chicago. An Emirates flight also from Dubai would be rerouted to Pittsburgh. But there remained the question of a Korean Air flight somewhere over Canada that was still headed for Dulles. The pilots seemed determined to make it to there; staff diplomatically suggested that they rethink the plan.

Meanwhile out on the airfield, the airport’s fleet of blowers, blasters, melters, plows and pushers — more than 150 pieces of equipment — were hard at work. Long convoys of orangy-yellow vehicles streamed across the runways, pushing, scooping and piling snow that would then be poured into giant melters or trucked to a distant area of the airport for dumping. But not all the work could be done by machine. The hundreds of white and blue edge lights used to mark runway and taxiway boundaries would have to be cleared by hand — a task that would take hours in the cold.

This year, the snow removal budget for Dulles, excluding personnel costs, is $15.3 million, according to the Metropolitan Washington Airports Authority; for National, it’s $2.5 million.

In all, about 250 people were on duty — many of whom spent the night at the airport or nearby to ensure that they would be in position and ready to work. A makeshift dining hall had been set up in one of the warehouses to feed the crews, who would work six -hour shifts, take six hours off and then return for another six hours until their work was completed.

Thursday morning’s efforts were helped by the airport’s preparation. Wednesday afternoon, while forecasters were speculating on how much snow would blanket the area, crews spread potassium acetate on runways and taxiways to prevent the snow from sticking to the pavement.

The mixture did its job, easing the task of clearing the snow Thursday.

The operations center buzzed with activity. A steady stream of chatter — barely understandable to those who don’t speak airportese — filled the room, as supervisors directed crews to hot spots.

“What’s the status of your removal area?” and “Bravo, Alpha, Foxtrot, Zulu,” airport lingo for the names of taxiways, were heard repeatedly.

About 10 a.m., Hall hopped into a truck to survey the progress. There was some: Most of the blue taxiway and white runway lights, invisible under the thick snowfall at 6 a.m., could be seen along the runway that Dulles officials hoped to reopen. But the runway itself was still blanketed in a layer of snow.

Meanwhile, the minutes ticked by. At least two inbound fights — an ANA flight from Tokyo and an Aeroflot flight from Moscow — were headed toward Dulles. Both were expected to land just after 12:30 p.m.

About 11:30 a.m., it became clear that a noon reopening would not be doable, but 12:30 was still a possibility, officials concluded. Now the question was whether the two flights might need to be diverted or could crews get the runway open and cleared in time?

Inside the airport operations center, the minutes ticked away – 12:27, 12:31 . . . .

Then at 12:37 p.m., the announcement came through: The runway known as 1R/19L was open for business.

About 20 minutes later, the first plane, the Aeroflot flight, touched down.

Up in the tower, the controllers asked the pilots for their assessment of the runway. A few anxious seconds passed in the airport operations center.

And then, in a thick Russian accent, the Aeroflot pilot replied: “Perfect.”