I have read that FAA announced these as the times the Towers were struck. Can anyone inform me as to standard FAA procedures for keeping track of flights, and when and in what manner FAA announced these times as the times the Towers were struck. I assume that the FAA's basis for the statement would be the cessation of the transponder signal. Is this correct? As you probably know the times are subsequent by quite a few seconds to the seismic events reported by the American Geophysical Union. I may have occasion to refer to this information in getting a resolution through my City Council.