US airlines have cancelled more than 800 flights on Christmas Day as the Omicron variant continues to wreak havoc on holiday travel plans.
Delta, United Airlines, Jet Blue and American Airlines were the worst affected airlines by the ongoing disruption.
In a statement, United Airlines said: “The nationwide spike in Omicron cases this week has had a direct impact on our flight crews and the people who run our operation.
“As a result, we’ve unfortunately had to cancel some flights and are notifying impacted customers in advance of them coming to the airport.”
By 9am, 284 Delta flights, 238 United Airlines flights, 120 JetBlue flights and 88 American Airlines flights had been cancelled, according to the Flight Aware tracking website.
More than 600 flights were cancelled on Christmas Eve.
A Delta spokesperson apologised on Friday to passengers who had their holiday travel plans disrupted.
“Delta people are working hard to get them to where they need to be as quickly and as safely as possible on the next available flight.”
The travel chaos came after the Transportation Safety Administration had earlier said the number of passengers travelling over Christmas was returning to pre-pandemic levels.
Globally more than 4,500 flights have been cancelled over the Christmas weekend, as a mounting wave of Covid infections driven by the Omicron variant created greater uncertainty and misery for holiday travellers.
German airline Lufthansa cancelled 12 flights to the US due to a “massive rise” in sick pilots.
The airline refused to say whether the pilots had tested positive to Covid-19 or been forced into quarantine. Affected passengers flying to Houston, Boston and Washington were booked on other flights.