The entrance used to behind where the Northwest ticket counter was. Right next to those restrooms there. Next to the back door into the cafeteria.
I can remember being a kid twenty plus years ago wanting to go up there but it being closed. I don't recall it ever being open.
I want to say you can still see the stairs there but don't quote me.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.