Chase-LeTourneauUniversity 2011

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U.S. Department of Transportation , Federal Aviation Administration APR - 8 !DU . ' Office of the Chief Counsel Bruce A. Chase, Assistant Chief Instructor School of Aeronautical Science, Flight Department LeToumeau University P.O. Box 7001 Longview, TX 75607-7001

Dear Mr. Chase:

800 Independence Ave., S.W.

Washington, D.C. 20591 This letter is in response to your May 25, 2010 request for interpretation regarding the meaning of"visual approach slope indicator" as referenced in 14 C.F.R. § 91.175(c)(3)(vi). You ask whether the term is specific or whether it would include Precision Approach Path Indicators (PAPI), tri-color visual approach slope indicators, pulsating visual approach slope indicators, or an alignment of elements system'.· From your question asking whether the tei-rn "visual approach slope indicator" is specific, we infer that you are referring to the lighting aids described in the Aeronautical Information Manual, Section 2-l-2(a), as a type of visual glideslope indicator that provides visual descent guidance information through a series of lights arranged in bars that display red or white lights. See FAA, Aeronautical Information Manual, Section 2-l-2(a) (Mar. l 0, 2011 ). In the remainder of this interpretation we will refer to this system as a VASI. A reason that§ 9l. l 75(c)(3) enumerates certain visual references in the runway environment is to ensure that pilots conducting instrument approaches can verify the position of the aircraft when making an instrument approach. See 46 Fed. Reg. 2280, 2282 (Jan. 8, 1981) {"Use of [inappropriate) landmarks can result in mistaken identification of position or aircraft flight path."). Further, the preamble to the rule does not indicate an intent to limit the rule to VASI systems. See 46 Fed. Reg. 2280; 45 Fed. Reg. 14802 (Mar. 6, 1980). The FAA interprets "visual approach slope indicat~r," as used in § 91.175(c)(3)(vi), to include PAPI systems. The rule was implemented before PAPis were widely used in the national airspace system. However, P APis are now used to replace VAS Is. See FAA, Navigation Services, . ,, http://www.faa.gov/about/office_ org/headquarters_ offices/ato/service_ units/techops/navserv ices/lsg/papi/ (last viewed August 13, 2010).

Furthermore, P APis and VAS Is share similar characteristics, including the light units used to project glide path, and the. colors (red and white) used to indicate whether an aircraft is above, on, or below glide path. Accordingly, a PAPI is an appropriate item of reference for the purposes contemplated by the regulation.

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Similarly, the FAA would consider tri-color visual approach slope indicators, pulsating visual approach slope indicators and alignment of e1<?ments systems as appropriate items of reference. All are types of visual glide slope indicators, appear on U.S. Terminal Procedures Charts where applicable, and are therefore identifiable to the pilot. As such, these systems may serve as visual references for pilots when determining whether to descend below decision altitude (DA), decision height (DH),'qr minimum descent altitude (MDA), when using the provisions of§ 91.175(c)(3).

We note that this interpretation would also apply to the use of "visual approach slope indicator" in§ 121.651.

This response was prepared by Dean Griffith, Attorney, and Robert Frenzel, Manager, Operations Law Branch in the Regulations Division of the Office of the Chief Counsel, and was coordinated with the Air Transportation Division, Flight Technologies and Procedures Division, and General Aviation and Commercial Division of Flight Standards Service. Please contact us at (202) 267-3073 if we can be of further assistance.

Sincerely,

,-? J~ L1 - /th~.u 4 ~ //f/u~ Rebecca B. M~herson ... ' Assistant Chief Counsel for Regulations, AGC-200