There have been at least 15 reports of staffing problems at the Federal Aviation Administration air traffic control facilities that have prompted delays across the country Friday, even as airlines cut 4% of their flights at 40 major airports.

Here’s a look at some of the recent impacts:

• The control tower at Washington’s Reagan National airport is again short-staffed until 10 p.m. ET tonight after an earlier staffing problem was reported there this morning. The FAA says delays for flights headed to DCA average about 83 minutes and only 24 planes will be allowed to land each hour.

• Flights headed to San Francisco today must wait on the ground about an hour for takeoff. The control tower at SFO is short-staffed until 3 p.m. ET.

• Atlanta Hartsfield-Jackson International Airport is seeing delays for planes departing of 45 minutes, and increasing, according to the FAA. The Atlanta Air Route Traffic Control Center, which manages flights en route at higher altitudes, is short-staffed this afternoon.

• Newark Liberty International Airport’s control tower is short-staffed until 2 p.m. ET. The TRACON facility handling flights approaching and departing Newark was short-staffed earlier.

• The control at airports in New Orleans, Austin, Texas and Ontario, California, were also short-staffed today.

• TRACONs, which handle flights arriving or departing airports, do not have their full complement of controllers this afternoon in Houston, Phoenix, and Southern California.

• And centers, which handle flights en route, are also short-staffed this afternoon in Dallas and Jacksonville. The Boston center was short-staffed earlier today.