14 CFR §125.321
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
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.