EXPLAINER: Why are so many flights being canceled?

The forces that have scrambled thousands of flights since Christmas Eve could ease in January, but that's cold comfort to the millions of flyers with New Year's plans.

And if 2021 has taught us anything, it’s that 2022 will likely be just as unpredictable.

Here’s a look at what has mucked up flights for thousands of people this holiday season, and what could happen over the next few weeks.

WHAT HAPPENED?

Airlines weren't spared from the spread of the omicron variant, which knocked out flight crews at airlines that had already reduced the size of their workforces following the collapse of air travel in 2020.

The wave of omicron infections arrived at the same time that crowds began to pack airports for holiday travel. Then the Pacific Northwest and other areas were slammed with cold and heavy snowstorms.

The convergence of all three forced airlines to cancel thousands of flights starting on Christmas Eve. As of Thursday afternoon, about 7,800 flights departing from, going to, or within the U.S. have been scratched, according to flight-tracking firm FlightAware. More than 1,100 of those were on Thursday.

The U.S. was not alone. There have been thousands of cancellations abroad. European and Australian airlines report the same logistical issues dealing with COVID-19 and flight crews. Chinese airlines have made up a large percentage of cancellations.

To put that in perspective, most flights were OK. There are nearly 70,000 flights a day, globally, said aviation data provider Cirium.

WHEN MIGHT THINGS IMPROVE?

U.S. health officials this week halved guidance to five days of quarantine for asymptomatic Americans who catch the coronavirus. Airline industry experts say that will alleviate the staffing issues that have forced airlines to scratch flights — but the flight...