Originally Posted by Ian Goddard

There is a "smoke" trail in the wake of Fight 77, which I suspect is ground dust drawn up into the engines. Aerial photos indicate local ground was exposed dirt, being an area under construction. While jet engines don't emit "smoke" (contrails at high elevation are a product of moisture condensation), in this case, drawing in air with massive force a few feet above dusty ground, the engines would be expected to draw in available ground-resting aerosols, depositing them along Flight 77's wake over the dusty ground. I see no data to suggest that Flight 77 is not visible in the Pentagon videos. ~Ian