14 CFR § 437.53
Pre-flight and post-flight operations
July 13, 2020
A permittee must protect the public from adverse effects of hazardous operations and systems in preparing a reusable suborbital rocket for flight at a launch site in the United States and returning the reusable suborbital rocket and any support equipment to a safe condition after flight. At a minimum, a permittee must—
(a) Establish a safety clear zone that will contain the adverse effects of each operation involving a hazard; and
(b) Verify that the public is outside of the safety clear zone before and during any hazardous operation.