Thomey-GeneralDynamics 2012

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U.S. Department
of TronsportaJion
Federal Aviation
Administration
fl-CT 11 ml
Mr. Gary B. Thomey
Chief Pilot
General Dynamics
44830 Cockpit Court
Dulles, VA 20166
Dear Mr. Thomey:
Office of the Chief Counsel 800 Independence Ave., S.W.
Washington, D.C. 20591

This letter is in response to your June 11 and June 21, 2012 requests for interpretation of section 91.175(c), Title 14, Code of Federal Regulations. You ask whether a pilot can descend below 100 feet above the touchdown zone elevation and land during an instrument approach if the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used. You also questioned whether § 91.175(d)(2) applies to part 91 operations. As stated in your letter, the pilot in your scenario is not conducting an Enhanced Flight Vision Systems (EFVS) approach. A pilot conducting an instrument approach procedure may not operate an aircraft below decision altitude (DA), decision height (DH) or minimwn descent altitude (MDA) unless he or she can meet three requirements. First, the aircraft must be "continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers . .. ." § 91.175(c)(l). Second, "[t]he flight visibility [may not be] less than the visibility prescribed in the standard instrwnent approach being used(.]" § 91.175(c)(2). And, third, certain visual references in the runway environment must be "distinctly visible and identifiable to the pilot[.]" § 91.175(c)(3) (i)-(x). In your letter you refer to a pilot who reaches l 00 feet above the touchdown zone by using the approach lights as a runway-environment visual reference and ask if the pilot may continue to descend if the flight visibility falls below what is published in the standard instrument approach procedure. As described above, being able to identify a specified runway-environment visual reference is one of the three requirements that a pilot must meet to descend below DA/DH or MDA. The pilot must also meet the other two requirements of § 91.175(c) when operating below DA/DH or MDA. Accordingly, the flight visibility must meet the minimwns prescribed in the instrument approach during the entire time an aircraft is operating below DA/DH or MDA. See§ 91.J 75(c)(2). If the flight visibility falls below the prescribed minimums the pilot must execute a missed approach procedure. See§ 91.175(c) (stating a pilot may not operate an aircraft below the authorized MDA or continue an approach below the authorized DA/DH unless all three requirements are met). Additionally, we note for anon-EFVS approach the flight visibility may not be less than the

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visibility prescribed in the standard instrument approach procedure being used for the aircraft to land. See§ 91.175(d)(2).

Regarding whether§ 91.175(d)(2) applies to part 91 operations, the answer is yes. Section 91.175(d)(l) applies to approaches conducted usingEFVS; section 91.175(d)(2) applies to all other instrument approaches conducted under parts 91, 121, 125, and 135. See EFVS Notice of Proposed Rulemaking, 68 Fed. Reg. 6802, 6805 (Feb. 10, 2003) ("For all other operations that are not conducted under § 91.175(!) [EFVS approaches], the pilot could not land the aircraft if the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used."). Therefore, any part 91 non-EFVS instrument approach flown under the provisions of§ 91.175 would need to comply with§ 91.175(d)(2) when landing.

This response was prepared by Dean E. Griffith, an attorney in the Regulations Division of the Office of the Chief Counsel. It was coordinated with the General Aviation and Commercial Division and the Flight Technologies and Procedures Division of Flight Standards Service. Please contact us at (202) 267-3073 if we can be of additional assistance.

Sincerely,

R1:::ef~¥::--Assistant Chief Counsel for International

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