; (B) the Department of Defense; (C) aircraft manufacturers; (D) institutions of higher education; and (E) any other stakeholders the Administrator determines appropriate. (b) Report Not later than 2 years after the date of enactment of this Act, the Administrator shall submit to the appropriate committees of Congress a report on the results of the study conducted under subsection (a), together with recommendations to facilitate the safe operation and integration of hypersonic aircraft into the national airspace system. (c) Definition of hypersonic In this section, the term hypersonic means an aircraft or flight operating at speeds in excess of Mach 5 and above. 909. Operating high-speed flights in high altitude Class E airspace (a) Consultation Not later than 12 months after the date of enactment of this section, the Administrator, in consultation with the Administrator of the National Aeronautics and Space Administration and relevant stakeholders, including industry and academia, shall identify the minimum altitude above the upper boundary of Class A airspace at or above which flights operating with speeds above Mach 1 generate sonic booms that are inaudible at the surface under prevailing atmospheric conditions. (b) Rulemaking Not later than 2 years after the date on which the Administrator identifies the minimum altitude described in subsection (a), the Administrator shall publish in the Federal Register a notice of proposed rulemaking to amend sections 91.817 and 91.818 of title 14, Code of Federal Regulations, and such other regulations as appropriate, to permit flight operations with speeds above Mach 1 at or above the minimum altitude identified under subsection (a) without specific authorizations, provided that such flight operations— (1) show compliance with airworthiness requirements; (2) do not cause a measurable sonic boom overpressure to reach the surface