DA 10-1002 Federal Communications Commission Washington, D.C. 20554 June 2, 2010 Melissa McCarthy General Manager, OCAS, Inc. 1934 Old Gallows Rd, Suite 350 Vienna, VA 22182 Dear Ms. McCarthy: We have received your request on behalf of OCAS, Inc. (“OCAS”), dated January 14, 2010, for a determination from the Federal Communications Commission that an antenna structure for which an OCAS audio visual warning system ("AVWS") has been authorized and deployed be exempt from the continuous lighting requirements under 47 C.F.R. §17.51.1 You state that OCAS’ AVWS is an integrated radar-based obstacle avoidance system that activates obstruction lighting and transmits audio warnings to alert pilots of potential collisions with obstacles, and that the obstruction lights and audio warnings are inactive when there is no air traffic around the obstruction. You further note that the Federal Aviation Administration (FAA) has found the AVWS provides “…an equivalent level of safety and is a suitable alternative to the marking and lighting requirements of obstacles as recommended in [its Advisory Circular] 70/7460-1K," and that the FAA is preparing changes to its Advisory Circular 70/7460-1K to incorporate AVWS as an acceptable form of marking and lighting.2 Section 17.51 of the Commission’s rules provides that red obstruction lighting shall be exhibited from sunset to sunrise and high intensity and medium intensity obstruction lighting shall be exhibited continuously “unless otherwise specified.”3 Section 17.51 by its terms recognizes that the lighting specifications for a particular tower may not require that the lights be continuously exhibited. Accordingly, where the FAA has issued a Determination of No Hazard for a tower based on the use of an AVWS and where the use of AVWS for that tower is specified in the 1 We note that OCAS has also filed a petition requesting that the Commission amend its rules to permit owners and operators of antenna structures and other air navigation obstacles to secure authorizations to operate radar systems and transmit audible signals over certain frequencies as part of AVWS operation. See In the Matter of Establishment of Audio Visual Warning System as New Subpart T to Part 87 of the Commission's Rules and Regulations to Authorize Advanced Audio Visual Warning Systems for Antenna Structures and other Air Navigation Obstacles, RM 11596, Petition for Rulemaking of OCAS, INC., filed March 4, 2010. Nothing in this letter is intended to prejudge the outcome of that petition or to authorize use of any radio frequencies in connection with OCAS’ AVWS. 2 See "Changes to Federal Aviation Administration (FAA) Advisory Circular (AC) 70/7460-1K, Obstruction Marking and Lighting," memorandum from Kevin Haggerty, Manager, Obstruction Evaluation Services, FAA to Obstruction Evaluation Personnel (June 15, 2009). 3 47 C.F.R. § 17.51. DA 10-1002 2 Commission’s Antenna Structure Registration database, Section 17.51 does not require continuous exhibition of lights on that tower.4 You may contact Michael C. Smith of our office at 202-418-0584 if you have any questions regarding this letter. Sincerely, Jeffrey S. Steinberg Deputy Chief Spectrum and Competition Policy Division Wireless Telecommunications Bureau 4 The Commission has released a Notice of Proposed Rulemaking seeking comment on proposed changes to section 17.51 and this determination is subject to any rule changes that the Commission may promulgate in that proceeding. See In the Matter of Amendments to Modernize and Clarify Part 17 of the Commission’s Rules Concerning Construction, Marking and Lighting of Antenna Structures, RM 11349, Notice of Proposed Rulemaking, FCC 10-53 (released April 20, 2010).