I think something that's happening when these questions arise is the pointing- out of the convoluted circular logic the gov't uses when answering questions. For example, someone asks, "What findings have you come up with in terms of the massive amount of insider trading days prior to 9/11?" And the gov't answers, "We have no proof that Al Qaeda benefitted from 9/11, so it's a non-issue."

Same thing here. "Has anyone checked the storage facilities or boneyards for missing planes?" Gov't responds, "You dummies. The planes were hijacked by 19 members of Al Qaeda. How could they have switched planes in mid-air?" And they'll leave it at that.