Holiday travel nightmare continues with COVID-related flight cancellations

The omicron variant continues to wreak havoc on holiday travel from coast to coast.

Over the weekend, airlines reported more than 3,000 flight cancellations with at least one stop in the U.S, according to FlightAware, and the travel troubles don't seem to be letting up anytime soon. As of 11:30 a.m. Monday morning, nearly 1,000 flights had already been canceled, and the number was steadily creeping up by the hour.

United, Delta, JetBlue, American and Alaska cited the recent COVID-19 surge as one of the reasons for the cancellations because it has left them with crew shortages. In an effort to avoid more disruptions, JetBlue and Alaska have even resorted to offering extra pay to healthy employees who can pick up additional shifts.

Winter weather in the western part of the country didn't help -- slamming airports in Seattle, Los Angeles and Denver. Those three airports accounted for more than 600 flight cancellations on Sunday alone.

"COVID delivered this disruption," Spokesperson for the Allied Pilots Association Capt. Dennis Tajer said. "And it just shows you how tight the buffer is in the airline business right now, where they're trying to fly as many flights as possible with just a handful of folks. So this is a little bit of a, you can't plan for something like this, but you certainly should have a little bit better of a buffer, especially in this important travel period where folks are trying to get to their families."

A majority of the flight cancellations luckily landed on traditionally slow travel days -- Christmas Eve and Christmas -- but there are still an estimated 16.5 million more fliers before the end of the holiday travel rush, according to the Transportation Security Administration.

"Omicron places airlines in a very tough position," aviation expert Henry Harteveldt told ABC News. "Still reeling from major financial losses in 2020, airlines don’t want to forfeit any opportunity to generate revenue and, possibly, profits. Plus, no airline wants to cancel fully booked flights at any time -- especially at Christmas. Given the random nature of how omicron strikes people, it’s also impossible for airlines to know who will get sick."

He says that for now there is no end in sight to the travel chaos.

"It’s impossible to predict an end date for the omicron-related cancellations," Harteveldt said. "Unlike when an airline suffers a disruption caused by weather, this virus is random. The best way to estimate its impact on airlines and other industries is to look at the broader trend."

Airlines for America, the group that lobbies on behalf of all major U.S. airlines, has been calling on the Centers for Disease Control and Prevention to shorten the quarantine time for fully vaccinated individuals in attempt to minimize disruptions from the omicron surge.

"The omicron surge may exacerbate personnel shortages and create significant disruptions to our workforce and operations," Nick Calio, A4A's CEO, said in a letter on Thursday to CDC Director Rochelle Walensky.

Calio proposed the isolation period to be shortened to five days from symptom onset for breakthrough infections.

"In turn, those individuals would be able to end isolation with an appropriate testing protocol," Calio wrote.

The letter comes after Delta Air Lines and JetBlue Airways, both A4A members, also asked for isolation periods for fully vaccinated individuals to be shortened.

ABC News' Joanne Aran and Erielle Reshef contributed to this report.