14 CFR § 121.551
Restriction or suspension of operation: Domestic and flag operations
July 13, 2020
When a certificate holder conducting domestic or flag operations knows of conditions, including airport and runway conditions, that are a hazard to safe operations, it shall restrict or suspend operations until those conditions are corrected.
[Doc. No. 28154, 61 FR 2613, Jan. 26, 1996]