US airlines called off hundreds of flights for a third day in a row on Sunday as surging Covid-19 infections due to the highly transmissible Omicron variant grounded crews and forced tens of thousands of Christmas weekend travellers to change their plans.
Commercial airlines cancelled 656 flights within, into or out of the United States on Sunday, slightly down from nearly 1,000 from Christmas Day and nearly 700 on Christmas Eve, according to a tally on flight-tracking website FlightAware.com.
Further cancellations were likely, and more than 920 flights were delayed.
The Christmas holidays are typically a peak time for air travel, but the rapid spread of the Omicron variant has led to a sharp increase in COVID-19 infections, forcing airlines to cancel flights with pilots and crew needing to be quarantined.
Globally, FlightAware data showed that nearly 2,150 flights were called off on Sunday and another 5,798 were delayed, as of 9.40am EST (1440 GMT).