As the holiday weekend draws to a close, it has been anything but merry for tens of thousands of stranded airline passengers who had their flight canceled due to a flare-up of the omicron variant that resulted in staffing shortages of pilots and crew for several major airline carriers. Data tracker FlightAware.com shows US flight cancellations exceeded 2,400 in just the past 48 hours.The situation has yet to ease on Sunday as total cancellations within, into, or out of the U.S. topped 754 flights as of 1300 ET. On Christmas day, U.S. cancellations topped nearly 1,000. Henry Harteveldt, president of...