The Federal Aviation Administration is warning more air travel headaches may be in store, even as airlines cancel thousands of flights because of coronavirus crew shortages and other issues. The FAA said Friday an “increased number” of its own employees are testing positive for the virus. That could force it to implement health and cleaning procedures that reduce the number of flights the system can handle. “To maintain safety, traffic volume at some facilities could be reduced, which might result in delays during busy periods,” the FAA said. Airlines canceled more than 11,000 flights since Christmas Eve, including more than 1,000 already scrapped from Saturday and Sunday schedules. But none of those were the result of FAA issues, the agency said. The Transportation Security Administration told CNN on Thursday that it has “adequate staff to cover flight schedules and passenger volumes.” The TSA expects 10 million more people to pass through airport screening between now and the end of the day Monday. Heavy holiday travel is colliding with a spike in coronavirus cases. Staffing shortages Airlines have been canceling flights as they face staffing shortages. They had been staffing up and bringing back employees from cost-cutting leaves of absence. Airline payrolls numbered 718,000 in October, the most recent data available from the Bureau of Transportation Statistics, up from 669,000 a year earlier. But the industry says the omicron variant of the coronavirus is sidelining its teams, and successfully asked federal officials to cut back the guidelines for isolation and quarantine. As airlines grapple with crews unavailable for work or stranded out of place, several are signaling the disruptions will persist.