[Code of Federal Regulations] [Title 33, Volume 1] [Revised as of July 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 33CFR67.05-5] [Page 166] TITLE 33--NAVIGATION AND NAVIGABLE WATERS CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PART 67_AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES --Table of Contents Subpart 67.05_General Requirements for Lights Sec. 67.05-5 Multiple obstruction lights. When more than one obstruction light is required by this part to mark a structure, all such lights shall be operated to flash in unison.