Reporting potentially hazardous meteorological conditions and irregularities of ground facilities or navigation aids

When a Part 121 pilot in command encounters hazardous weather or discovers a problem with a ground facility or navigation aid during flight, they must notify an appropriate ground station as soon as practicable if they believe this information is essential to the safety of other flights. This is the pilot's judgment call—they decide what rises to the level of being safety-essential for others.

The regulation also places a responsibility on the ground station that receives such a report: they must forward the information to the agency that operates the affected facility (such as the FAA for navaids or airport operators for ground facilities).

This reporting chain ensures that safety-critical information discovered by one crew gets quickly disseminated to other pilots and to the people who can fix the problem, creating a real-time safety network across the aviation system.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*