14 CFR § 121.553
Restriction or suspension of operation: Supplemental operations
July 13, 2020
When a certificate holder conducting supplemental operations or pilot in command knows of conditions, including airport and runway conditions, that are a hazard to safe operations, the certificate holder or pilot in command, as the case may be, shall restrict or suspend operations until those conditions are corrected.
[Doc. No. 28154, 61 FR 2613, Jan. 26, 1996]