I live in Middletown MD, for the last 12 years and until recently in bound planes on descent were much more east of my house. More over the city of Frederick MD. I have noticed many huge planes descending directly overhead and low, guessing 5,000 - 10,000 ft. Has there been a flight path change for IAD? I am always looking up and listening to engines. I know planes for BWI come over my house from the west at about 15,000 ft but these heavies coming down from the north is fairly new. Thanks for your help.