Refer to a Dr Grossman and go through some video material of that fateful day and check out some visuals of the still burning towers and note a certain triangular (ufo?) shape in hazy white, like smoke,- on the darker smoke back ground. Smoke is supposed to move away and cannot stay the same shape for such a long time (say for 2 minutes?) Take screen shots of the videos of the burning towers and enlarge the images at leisure. Was this ufo ensuring that ‘all goes well” during the attack? This ufo was suppose to be invisible but due to the heat and the back ground and all that it wasn’t completely invisible.?