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U.S. Department of Transportation, Docket Operations 

West Building Ground Floor, Room W12-140 

1200 New Jersey Avenue, SE .. 

Washington, DC 20590 Fl3 ! 0 A c1: ll 

14-11.71(a)(1) 

Reference 

14-11.71(a)(2) 

14-11.71(a)(3) 

14-11.71(a)(4) 

Richard Terrill 

PO Box 2220 

Saratoga, CA 95070-0220 

richard@rt-aviation.com 

Doc. No. 18334, 54 FR 34292, Aug. 18, 1989, as amended by Arndt, 91-220, 55 FR 43310, Oct. 26, 

1990; Arndt. 91-223, 56 FR 41052, Aug. 16, 1991; Arndt. 91-231, 57 FR 42672, Sept. 15, 1992; 

Arndt. 91~248; 61 FR 5F1, Feb. 9, 1996; Arndt. 91-251, 61 FR 34560, July 2, 1996; Arndt. 91-285, 

69 FR 77599, Dec. 27, 2004; Arndt. 91-296, 72 FR 31679, June 7, 2007; Arndt. 91-309, 74 FR 42563, 

Aug.21,2009 

Commonly known as: 

Title 14: Aeronautics and Space 

Part 91- GENERAL OPERATING RULES 

Subpart C- Equipment, Instrument and Certificate Requirements 

§ 91.205 • Powered civil aircraft with standard category U.S. airworthiness certificates: 

instrument and equipment requirements. 

{a){11)- For small civil airplanes certificated after March 11, 1996, in accordance with part 23 

of this chapter, an approved aviation red or aviation white anticollision light system. In the 

event of failure of any light of the anticollision light system, operation of the aircraft may 

continue to a location where repairs or replacement can be made. 

Reword a potentially ambiguous regulation that has been interpreted in such a way as to ground 

aircraft that are legally and practically airworthy. The clarification of 91.205(a)(11) will make it 

explicitly clear that an aircraft only requires a single, fully operational anticollision light system. It 

would further clarify that failure of a component in an anticollision light system only affects 

airw01thiness of aircraft with a single anticollision light system installed. 

Proposed change to the language of the regulation 

Reword this regulation as follows. In practical terms this is only a grammar change, and does 

not change the intent or safety impact. Bold emphasis shows the additional clarifying text. 

(a}{11)- For small civil airplanes certificated after March 11, 1996, in accordance with part 23 · 

of this chapter, an approved aviation red or aviation white anticollision light system. If an 

aircraft has two or more anticollision light systems installed, only one of the light systems 

must be fully operational for the aircraft to be airworthy. In aircraft with. only one 

anticollision light system installed, in the event of failure of any light of the anticollision light 

system, operation of the aircraft may continue to a location where repairs or replacement 

can be made. 

Explanation of the benefit to public interest 

This amended regulation will preclude misinterpretation that has lead to unnecessary 

canceling of flights. This will allow more flight operations in the GA fleet, and also prevent 

the frustration that results from cancelled practical flight tests due to ambiguous 

airworthiness criteria. 

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14-1L71(a)(S) The above-referenced regulation, as written, permits an aircraft to have either a red or a white 

light system (the key word is "or" in the first sentence). The second sentence, however, has been 

interpreted by some pilots to mean that if an aircraft has two anticollision lighting systems, and 

any ofthe lights in either system is not working, then the aircraft is notairworthy. The problem is 

the 2"dsecond sentence in the regulation with the phrase "failure of~ light ... " This issue is the 

word 'any' may be seen as all-inclusive if "the anticollision light system" is deemed to include all 

of the installed anticollision light systems. 

A red rotating beacon by itself is sufficient to provide traffic awareness to other aircraft and 

ground personnel. A pair of white strobe lights, one each located on the ends of the wings is 

equally sufficient for safety. If the strobes were both working and the red beacon on the tail was 

not working, safety is not compromised. If the red beacon is working and one of the two strobes 

is not working, safety is not compromised. This is evidenced by the many aircraft that have only 

one anticollision light system installed and are operated without collision events. 

A practical example is the Cessna 172SP, with a type certificate approval of May 1, 1998 

(http:fhj__w_w.airiNeb.faa.gov/Regulato_r:_y__anQ__Guidanc~ LibraryL_r:gMakeModel.nsf/0/a9c23e98'!Z 

?4~Ji~!3.§257a£~_Q9_?709_?_f/_$._E.!_l,_~/lh1_LI3~!3~_p_Qf.). This aircraft has both the red rotating 

beacon and the white strobe lights. Both items are listed as standard ("S") equipment in the 

Cessna 1725 approved flight manual, so Cessna did not provide more restrictive (than 91.205) 

equipment requirements. 

Another example is an older aircraft that did not have strobe lights as a factory option. If they are 

added after the fact through an STC, then some conservative pilots (or examiners) may deem that 

the intent of 91.205(a)(11) is good and should apply retroactively. Or the STC may be considered 

to reset the airworthiness date of the entire ship to after the 1996 cutoff in the regulation. 

14-11.71(a)(6) At our flying club we have one aircraft for which the strobes will not always work on just the 

battery power, they require the 14V of the alternator. They work fine once the engine is running, 

but during a preflight inspection they are intermittent. This aircraft has been rejected for flight 

many times by diligent pilots, when the airplane was in all practical regards airworthy. 

14-11.71(b) There is no compliance cost or regulatory burden to operators and pilots. There are no changes to 

aircraft documentation, operation procedures or checklists. The cost will be limited to the effort 

required to review, receive comment and modify the regulation. Promulgation will be during the 

normal course of publishing updated regulations. 

About Me I hold a commercial instrument airplane pilot certificate, instrument flight instructor certificate, 

advanced ground instructor certificate. I am an aircraft owner, and chief pilot at a flight school. 

Thank you for considering this request. 

P.S. 14-11.63(a)(1) references the URL http://www.{aa.gov/regulations for online submission of these 

requests, but that is not a valid URL. 

cf: Paul King, San Jose FSDO 

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