; and (ii) in the case of an airport with an operational air traffic control tower, receives approval from the air traffic control tower. (c) Scope of regulations (1) In general In determining whether a person may operate an unmanned aircraft system under 1 or more of the circumstances described under paragraphs (1) through (3) of subsection (a), the Administrator shall use a risk-based approach and consider, at a minimum, the physical and functional characteristics of the micro unmanned aircraft system. (2) Limitation The Administrator may only issue regulations under this section for micro unmanned aircraft systems that the Administrator determines may be operated safely in the national airspace system. (d) Rules of construction Nothing in this section may be construed— (1) to prohibit a person from operating a micro unmanned aircraft system under a circumstance described under paragraphs (1) through (3) of subsection (a) if— (A) the circumstance is allowed by regulations issued under this section; and (B) the person operates the micro unmanned aircraft system in a manner prescribed by the regulations; and (2) to limit or affect in any way the Administrator's authority to conduct a rulemaking, make a determination, or carry out any activity related to unmanned aircraft or unmanned aircraft systems under any other provision of law. . (c) Table of contents The table of contents for chapter 448, as amended by section 2125 of this Act, is further amended by inserting after the item relating to section 44805 the following: 44806. Additional rulemaking authority. . 2127. Governmental unmanned aircraft systems (a) In general Chapter 448, as amended by section 2126 of this Act, is further amended by inserting after section 44806 the following: 44807. Public unmanned aircraft systems (a) Guidance The Secretary of Transportation shall issue guidance regarding the operation of a public unmanned aircraft system— (1) to streamline the process for the issuance of a certificate of authorization or a certificate of waiver