On a day like that they didn't need any help with the navigation. New York isn't hard to find and WTC was easy to spot. But like someone said above, was that just their luck or did they expect it? Did the forecasts from the day they bought their tickets already show CAVOK conditions in both NY and Washington for 9/11? Maybe they were waiting for a VFR day since I am not sure a low hour pilot could hit their targets using just instruments.