Earlier this month, Duffy said the government shutdown was adding stress to already overworked and understaffed air traffic controllers.

Flights departing for Los Angeles International Airport were halted briefly due to a staffing shortage at a Southern California air traffic facility, the Federal Aviation Administration said Sunday, when the agency also reported staffing-related delays in Chicago,

US air travel turmoil deepened as nearly 7,000 flights were delayed nationwide on Monday, with air traffic controller absences surging as the federal government shutdown reached its 27th day.

A U.S. Department of Transportation official said 44% of Sunday's delays stemmed from controller absences — up sharply from the usual 5%.