14 CFR § 125.321
Reporting potentially hazardous meteorological conditions and irregularities of ground and navigation facilities
July 13, 2020
Whenever the pilot in command encounters a meteorological condition or an irregularity in a ground facility or navigation aid in flight, the knowledge of which the pilot in command considers essential to the safety of other flights, the pilot in command shall notify an appropriate ground station as soon as practicable.
[Doc. No. 19779, 45 FR 67235, Oct. 9, 1980, as amended by Amdt. 125-52, 72 FR 31683, June 7, 2007]