Joel Rose

Sub-zero temperatures and other weather issues across the Northeast forced airlines to cancel thousands of flights and delay thousands more again on Monday, complicating their efforts to get aircraft and crews back in position for regular service.

The storm also impeded road travel across a wide swath of the central and eastern U.S.

In the south, ice brought down trees and power lines, cutting electricity to hundreds of thousands of homes and businesses.

with the most outages reported in Tennessee, Mississippi, and Louisiana.

Joel Rose, NPR News, Washington.

Sunday was the biggest single day for cancellations since the early days of the COVID pandemic in 2020, according to the aviation analytics company Sirium.

The vast majority of flights were canceled at some airports in the Northeast, around Washington, D.C., New York, and Boston.

American Airlines canceled more than half of its scheduled flights yesterday.

Delta and United, more than 40%.

In some places, the storm was all snow.

In others, it turned into sleet and freezing rain.

In much of the south, it left a coating of ice on roads and trees that made roads dangerous, if not totally impassable.

It also brought down trees and branches and power lines.

That left hundreds of thousands of homes and businesses without power across Tennessee, Louisiana, and Mississippi.

The Federal Aviation Administration moved quickly after the mid-air collision of an Army helicopter and a passenger jet, imposing temporary flight restrictions around Ronald Reagan Washington National Airport.

Now the FAA is making those restrictions permanent.

The agency says that will ensure that helicopters and airplanes no longer share the same airspace around the airport.

reducing the risk of another collision, like the one that killed 67 people in January of last year.

The National Transportation Safety Board plans to hold a meeting next week to detail everything that investigators believe contributed to the deadliest U.S.

aviation disaster in decades.