Where is the skull for Halo 3- the covanant?

In the part where you have a sky battle in a hornet go to the space where you try to kill an anti air wraith and a bunch of brutes. at the back of that cove you should see a tower much like the one that is in the second code. you stop at one hallway go to the end and turn around go to the end of that ledge and you should see the skull. At the back of the hallways there should also be a terminal.