The flight turmoil in the United States continued on Monday, as many people began their first trip in almost two years. However, at least 2,600 other flights were canceled on Monday due to the highly infectious Omicron variant. Cancellations accounted for only a small percentage of all flights, but the problem could spread during the holiday week. 

On holiday weekend, the airline canceled thousands of flights when a variant of Omicron struck a flight attendant. According to FlightAware, which provides aviation data, a total of approximately 2,300 US flights were canceled on Saturday and Sunday during Christmas weekend, with more than 3,500 worldwide. On Sunday alone, more than 1,300  flights were canceled in the United States and nearly 1,700 flights worldwide. Additionally, FlightAware reports that 12% of JetBlue Airlines, 6% of Delta Air Lines, 5% of United Airlines  and 2% of American Airlines flights had been shut down. 

Stock prices for United, Delta, American and Southwest (the four largest US airlines) all fell slightly. Regardless, travel has recovered significantly this year, and airport conditions have worsened. According to the Transportation Security Administration, about 2 million people passed checkpoints every day last week and Sunday. The number on Christmas Eve was much higher than last year and more than the same day two years ago.  Even in New York City, the Metropolitan Transportation Authority dealt with positive staff cases, 80% of whom are vaccinated. Under normal schedule, the subway was said to run on Mondays, with a few exceptions.