As it continues, the shutdown will increasingly affect air travel and even safety. Union officials are concerned about stress. Alaska Airlines warns that without FAA officials to sign off, the new Paine Field Airport near Seattle may not open as scheduled on Feb. 11. And Delta Air Lines’ plans to start flying its newest aircraft, the Airbus A220, by the end of January could also be slowed.

TSA has already tapped the pool of workers who can be shifted around, and is adding reinforcements to airports in New York, New Jersy, Chicago, Miami and Atlanta.

The U.S. Travel Association estimates that the standoff is costing the economy $100 million a day just in lost travel expenditures, and that airports, visas and Customs may become increasingly affected.

The Global Business Travel Association said that a survey of more than 400 members this past week revealed that more than two-thirds of those polled are concerned about a negative impact on their business if the shutdown continues.