You are reaching & you are not far from something solid. Many factors indicate the gravity of the threat-including Cheny's serious description & blow-by-blow of his physical removal from upper floors to the underground by Secret Service ( re-counted to Tony Snow on live TV ). They had real trouble, were surely in genuine danger. So are we all-still. Presumne Barksdale was used for fuel, since they would have not beeen fully fueled from Florida ( a short hop to DC ) & SAC was chosen as more secure post if they were to be holed up very long. Cheny said it was used due to the communication tools avail, but that was surely avail from Barksdale ( a SAC base ). I should expect some rational re-telling of events and drawing of conclusions by the informed conserv' media soon.
Many factors indicate the gravity of the threat-including Cheny's serious description & blow-by-blow of his physical removal from upper floors to the underground by Secret Service ( re-counted to Tony Snow on live TV ). This was part of it,too. I watched that on tv,and Cheney said they didn't even ask him,they just came in his office and physically picked him up and headed for the blast bunker. He said his feet only hit the floor sometimes,and they did their explaining to him on the way underground. This ain't how the SS acts when they think there MIGHT be a casual threat.
There was also the evacuation of the WH,as well as the helicopters taking Hassert and others out of DC and to underground command posts. They don't do this for something like crashing airliners.