Where lack of air traffic controllers is causing the most flight cancellations

The Federal Aviation Administration is reducing flights across 40 major airports because of shortages of air traffic controllers triggered by the ongoing federal government shutdown.

The shutdown, which has gone on for over 40 days since Oct. 1, has forced about 13,000 air traffic controllers and 50,000 security screeners to work without pay. 

The FAA has reduced flight volume by about 6% because of safety concerns, though according to data from Flightaware, some airports are experiencing far greater impacts than others.

Over the weekend major international airports saw flight cancellations spike. Here's a look at those impacted the most:

Percent of cancellations by origin airport

According to data from Flightaware, these 38 of the 40 airports impacted by FAA flight reductions because of the shutdown saw high numbers of cancellations from Nov. 7 through 11:15 a.m. on Nov. 10:

Even before the shutdown, the FAA had long been having shortages of air traffic controllers. In May, USA TODAY reported that the FAA was short 3,000 air traffic controllers nationwide.

Where most flights were canceled across the U.S.

Air traffic controllers continued working without paychecks during the shutdown as essential personnel. But some failed to show up as they looked for other jobs to make ends meet during the congressional impasse, so the FAA ordered airlines to cancel 4% of their flights during the weekend. More than 10,000 flights were delayed Nov. 9.

Contributing Bart Jansen, USA TODAY