The FAA's Remote Tower Systems (RTS) program sets the requirements a non-federal airport must meet to operate a remote tower in the U.S. National Airspace System. It covers the Concept of Operations, the Operational Safety Assessment, technical requirements, operational visual requirements, and a draft Advisory Circular.
As of the latest public information, the FAA has not certified a U.S. remote or digital tower for federal ATC. Non-federal programs at Leesburg (JYO) and Northern Colorado (FNL) ran under the RTS pathway; the Leesburg program ended in 2023 after the vendor withdrew from certification under updated System Design Approval criteria.
Passive testing of remote tower systems takes place at the FAA's William J. Hughes Technical Center in Atlantic City.