Nearly 1,000 flights within the U.S. were canceled and more than 900 delayed on Nov. 13, the first day after the government reopened. The FAA ordered cancellations to remain at 6% after the shutdown forced flight restrictions at 40 high-traffic airports.

Air traffic controllers who worked without pay during the 43-day shutdown are returning to full staffing, but it remains unclear when normal flight schedules will resume.

The shutdown may hurt the $31.5 billion FAA infrastructure replacement effort.