The 9/11 mystery plane?

On 9/11, a plane was flying over Washington. It caused people grave concern on the ground, but that plane has never been explained or talked about by the government. Ask the Pentagon, and they'll just blank you, the government basically says it doesn't matter. It wasn't even mentioned in the 9/11 commission. But what was it? CNN recorded footage of the plane flying around, for the most part it just looked like a dot in the sky, but then a closer picture of it which still looks vague, seems to reveal what it was. It looks like a Boeing 747 jumbo jet, with 4 engine, white, United States flag on the tail, blue line running down the fuselage and a bump above, behind the pit. That description fits the E4-B, a secret military aircraft that the Pentagon doesn't like discussing. The plane is basically desgined to carry on the fight should the government be knocked out in time fo wear, it was nicknamed during the cold war, the doomsday plane. I think it was the E4-B, what do you think it was? your thoughts and views? Here's a CNN photo of it, the top one, is the picture on 9/11, and the bottom picture is what they think it is. http://whatreallyhappened.com/IMAGES/doomsday_plane.jpg