From the location Ms. Renaud mentioned, it
would have been no problem at all for her to have had a clear,
unobstructed view of the aproach of whatever hit the ST...assuming
something did in fact hit via air.
I have been in that area many, many times and there was always a good
view of the Towers even FROM THE STREET LEVEL. Since she mentions she
is in the tallest building in the area, even more reason she would be
able to have a clear view of the harbor, and the subsequent approach
of anything via air.
Here are a few angles that illustrate the view she would've had from
the location she mentioned: