Peter R. wrote:


I ask this because I occasionally will arrive at the airport and preflight
much earlier than I anticipated, then call for my clearance only to
discover that ATC cannot find my flight plan. It then dawns on me that I
am attempting to get my clearance earlier than 1/2 hour prior to my
estimated departure time, which means the flight plan is not yet available
to the controller.

Another difference with DUATS and AFSS filed flight plans is with an
AFSS filed flight plan I have access to it immediately via the Tower's
FDIO. A DUATs flightplan doesn't get sent to the center immediately
therefore when you show up early I have no access to your flightplan
because it isn't in the system yet.