For the second day, the Federal Aviation Administration will continue to enforce its mandate to cancel 6% of flights at 40 high-traffic airports, as the U.S.

Reducing the number of flights nationwide is intended to relieve some pressure on air traffic controllers and maintain safe air travel. Most controllers are working mandatory overtime six days a week during the shutdown without pay, and some are taking second jobs to pay their bills, the National Air Traffic Controllers Association has said.

Editor’s note: This is a breaking news story and will be updated.

The approximate median annual wage for air traffic control specialists is $127,805, according to the FAA. The shortage of air traffic controller specialists is one of the reasons for the hectic stretch at Newark Liberty International Airport amid hundreds ...