Except as provided in section 7173 of this title, whenever the Secretary proposes to prescribe rules, regulations, and statements of policy of general applicability in the exercise of any function which is transferred to the Secretary under section 7151 of this title or section 60501 of title 49, he shall notify the Commission of the proposed action. If the Commission, in its discretion, determines within such period as the Secretary may prescribe, that the proposed action may significantly affect any function within the jurisdiction of the Commission pursuant to section 7172(a)(1) and (c)(1) of this title and section 60502 of title 49, the Secretary shall immediately refer the matter to the Commission, which shall provide an opportunity for public comment.