charlotte, atlanta, philadelphia, and washington, d.c. so if you were at an airport or trying to get into an airport in the northeast, here is a snapshot of what was happening behind the scenes. mountains of thick, heavy snow was enough to completely stop air travel at some northeast airports like reagan national outside of d.c. >> here's my problem right now. these are my two parallel taxiways and you can see the snow. i can get you from the land but i can't get you from the runways to the gate. >> reporter: they've been shut down for several hours as they try to clear the snow from the runways. they are nearly two dozen pieces of equipment like this on the runways trying to make it safe enough for planes to land. this right here is filled with cement, because that is necessary to stabilize this path as it lifts lots of heavy snow.