As the longest government shutdown in U.S. history drags on, airlines have been ordered to begin reducing operations on a phased-in basis.

Follow live updates as flight reductions begin today at 40 high-traffic airports in what officials have described as a "proactive" effort to alleviate pressure points.

The cuts will increase gradually over the next week, as air traffic controllers go without pay during the ongoing government shutdown.

Starting Friday, the FAA is reducing flights at 40 high-traffic airports, citing safety concerns amid the government shutdown.

Federal officials announced the 40 airports that will see a 10% flight reduction which includes Newark, Teterboro and New York's major airports.

Oakland International Airport, the other Bay Area airport affected by FAA flight reductions, had at least 12 cancellations on Friday morning, and 15 delays so far.

The Federal Aviation Administration will reduce flight capacity by 10% at 40 major airports across the country, officials announced during a press conference on Wednesday. The decision could cut thousands of flights per day.

The potential delay comes just two days after Houston’s William P. Hobby Airport issued a ground stop Tuesday afternoon for the same reason. That ground stop lasted until 6 p.m., while a ground delay continued until 9 p.m., according to Houston Airports.