[Code of Federal Regulations] [Title 14, Volume 2] [Revised as of January 1, 2008] From the U.S. Government Printing Office via GPO Access [CITE: 14CFR121.551] [Page 856] TITLE 14--AERONAUTICS AND SPACE CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PART 121_OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS-- Subpart T_Flight Operations Sec. 121.551 Restriction or suspension of operation: Domestic and flag operations. 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]