Major airlines at Newark Liberty International Airport are preparing to implement a new directive from the Federal Aviation Administration to reduce air traffic at high-volume airports.

The agency says there aren't enough air traffic controllers to keep up amidst the ongoing government shutdown. Airlines, like United Airlines, said they plan to implement this change in phases over the next week.

Twelve United flights out of Newark have already been cancelled for Friday, and about 40 United flights per day will be cancelled starting next Thursday.

"Over the last 24 hours, that partnership with United and FAA and all the airlines has been really strong,” said John Gooda, vice president of United Airlines Operations at Newark. “What the FAA shared both publicly and with the airlines, is their top priority is safety, just like ours. So, if we have to reduce the schedule just a little bit over this period to support that, we're very committed to doing so.”

Airlines are unsure how long these reductions will last, but United says for now all international flights will operate as normal.