14 CFR § 417.121 - Safety critical preflight operations.
(a) General. A launch operator must perform safety critical preflight operations that protect the public from the adverse effects of hazards associated with launch processing and flight of a launch vehicle. The launch operator must identify all safety critical preflight operations in the launch schedule required by § 417.17(b)(1). Safety critical preflight operations must include those defined in this section.
(b) Countdown. A launch operator must implement its countdown plan, of § 417.111(l), for each launch. A launch operator must disseminate a countdown plan to all personnel responsible for the countdown and flight of a launch vehicle, and each person must follow that plan.
(c) [Reserved]
(d) Meteorological data. A launch operator must conduct operations and coordinate with weather organizations, as needed, to obtain accurate meteorological data to support the flight safety analysis required by subpart C of this part and to ensure compliance with the flight commit criteria required by § 417.113.
(e) Local notification. A launch operator must implement its local agreements and public coordination plan of § 417.111(i).
(f) Hazard area surveillance. A launch operator must implement its hazard area surveillance and clearance plan, of § 417.111(j), to meet the public safety criteria of § 417.107(b) for each launch.
(g) Flight safety system preflight tests. A launch operator must conduct preflight tests of any flight safety system as required by section E417.41 of appendix E of this part.
(h) Launch vehicle tracking data verification. For each launch, a launch operator must implement written procedures for verifying the accuracy of any launch vehicle tracking data provided. For a launch vehicle flown with a flight safety system, any source of tracking data must satisfy the requirements of § 417.307(b).
(i) Unguided suborbital rocket preflight operations. For the launch of an unguided suborbital rocket, in addition to meeting the other requirements of this section, a launch operator must perform the preflight wind weighting and other preflight safety operations required by §§ 417.125, 417.233, and appendix C of this part.