More than 10,000 US flights were canceled and several airports closed on Tuesday as a monster storm dumped freezing rain, sleet and snow on a huge swathe of the country, a travel website said.
FlightAware reported that airlines grounded nearly 6,500 flights on Tuesday -- about 20% of US commercial flights -- and protectively canceled another 3,600 on Wednesday. Nearly 800 flights were canceled on Monday as the storm got underway.
Dallas-Fort Worth airport, a major hub, closed briefly earlier due to the ice storm and delays were averaging about three hours once it reopened.
Chicago's O'Hare, among the busiest airports in the world, had the most cancellations, with more than 1,300 flights affected as airlines prepared for blizzard conditions to strike in the afternoon. Another 350 flights were canceled at the city's secondary airport, Midway.
Most airlines stopped operating flights completely at both airports as the storm got fully underway, said Gregg Cunningham, a spokesman for the Chicago Aviation Department. "In addition, most of the airlines at O'Hare have indicated they will have limited or no flight operations tomorrow," he said in a statement.
"Some airlines expect to resume operations tomorrow afternoon at Midway, with the majority of flights expected to resume in the evening." No flights were going in or out of the Tulsa, Oklahoma airport, although it remained officially open.
A handful of flights were allowed to land in St Louis, Missouri but none were taking off.
Kansas City, Missouri's airport was officially closed. Some 900 flights were canceled in Dallas, 650 in Newark and nearly 1,100 at New York's LaGuardia and JFK airports.
"This storm is going to have a significant impact on airlines, particularly those with hubs in Chicago (United, American) and Newark (Continental)," FlightAware warned. Most airlines offered customers the chance to rebook flights at no extra charge.