14 CFR 121.561 : Aeronautics And Space (§ 1.1 To Parts 1311-1399) — (§ 110.1 To Part 199) — Federal Aviation Administration, Department Of Transportation (Continued) (§ 110.1 To Part 199) — Air Carriers And Operators For Compensation Or Hire: Certification And Operations (§ 110.1 To § 139.343) — Operating Requirements: Domestic, Flag, And Supplemental Operations (§ 121.1 To Appendix P To Part 121) — Flight Operations (§ 121.531 To § 121.590) — Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids.

4 Aug 2016

(a) Whenever he encounters a meteorological condition or an irregularity in aground facility or navigation aid, in flight, the knowledge of which he considers essential to the safety of other flights, the pilot in command shall notify an appropriate ground station as soon as practicable.

(b) The ground radio station that is notified under paragraph (a) of this section shall report the information to the agency directly responsible for operating the facility.

14 CFR 121.561
[Doc. No. 6258, 29 FR 19219, Dec. 31, 1964, as amended by Amdt. 121-333, 72 FR 31682, June 7, 2007]