Originally Posted by
MarkerInbound
In the US airport certification falls under Part 139 which includes AFRR services. Buried in the reg is a sentence, "...any supplemental operation (except an all-cargo operation)..." In the FAA system, most of the all cargo operations, even if they fly a regular schedule, are considered supplemental ops.
I believe FedEx and UPS are now considered Part 121 flag/domestic carriers for their scheduled ops although they still may use supplemental rules for some charter flights.
Don't know about the other U.S. freight dogs.