materials by commercial package delivery unmanned aircraft systems (a) In general Notwithstanding any other Federal requirement or restriction related to the transportation of hazardous materials on aircraft, the Secretary shall, beginning not later than 180 days after enactment of this section, use a risk-based approach to establish the operational requirements, standards, or special permits necessary to approve or authorize an air carrier to transport hazardous materials by unmanned aircraft systems providing common carriage under part 135 of title 14, Code of Federal Regulations, or under successor authorities, as applicable, based on the weight, amount, and type of hazardous material being transported and the characteristics of the operations subject to such requirements, standards, or special purposes. (b) Requirements In carrying out subsection (a), the Secretary shall consider, at a minimum— (1) the safety of the public and users of the national airspace system