The North American Aerospace Defense Command will conduct calibration flights over the Washington area on Thursday afternoon. The flights are meant to help calibrate systems and equipment used in responding to unknown or threatening aircraft.

The exercise will take place from 1 to 3 p.m. at about 2,000 feet. They will be flown by a Beechcraft King Air plane.

This comes two days before NORAD will be busy tracking Santa Claus on Christmas Eve. And it comes more than two weeks after NORAD conducted its most recent flight exercise over Washington.