Travelers showed up early for flights and prepared for frustrations at Minneapolis-St. Paul International Airport on Friday as the federal government’s mandate to cut 10% of the air traffic goes into effect amid the longest government shutdown in U.S. history.

The Federal Aviation Administration (FAA) mandated the cancellations as a safety measure at 40 major airports nationwide while air traffic controllers continue to work without pay, ratcheting up pressure on an already strained system.

Airlines were working to lessen the impact on customers, but travel analysts predicted messy outcomes.