"At the least September 14th through the 19th. While the national airspace was officially closed."
National airspace was re-opened partially on September 14th and completely on September 15th. I remember. I was manufacturing Boeing commercial airplanes at the time and it was very important how long national airspace was closed. I also remember thinking that it may have been opened too soon considering what had just happened.
Thee's always some planes flying -- that have to. CAP, organ transplant stuff, etc.