February 25, 2013

Ms. Gale A. Brewer

Council Member, District 6

The Council of The City of New York

563 Columbus Avenue at 87th Street

New York, NY 10024

Dear Ms. Brewer:

This letter responds to your December 11, 2012, petition to the Federal Aviation 

Administration (FAA) in which you request to amend § 45.23 of Title 14, Code of Federal 

Regulations. The proposed language for the amended rule would require the registration 

number of the aircraft to be displayed on the underside of the cabin in font large enough to be 

clearly visible to the naked eye.

In general, we use the following criteria to determine which petitions for rulemaking are of 

sufficient priority to initiate a rulemaking action:

1) The immediacy of the safety concerns the petition raises;

2) The priority of other FAA rulemaking actions; and

3) The resources we have available to address these issues.

The issue you raise is not a safety concern. The FAA’s limited rulemaking resources 

currently are being used to address numerous priority safety-related issues, including more 

than 30 initiatives to address legislative mandates, most with critical deadlines. 

Amendment 45-9, Nationality and Registration Marks on Fixed-Wing Aircraft, eliminated 

the 18-inch under wing marking requirements for fixed-wing aircraft. Amendment 45-15 

eliminated the 20-inch high bottom surface marking requirements for rotorcraft aircraft. 

After review of comments received and all the information available on under-wing marks, it 

was clear that these marks are useful for identification purposes only under limited 

conditions. The marks are of little value unless the aircraft is flying at an appropriate 

altitude, attitude and speed; the observer is situated directly below the flight path; and 

favorable light and weather conditions prevail. It was therefore determined by the FAA that 

the undersurface marks were ineffective and of little value in air-to-air identification.

The newer rotorcraft configurations, which have been designed for faster flight and more 

stability than the early designs, now have a compact, low-drag fuselage and tail surfaces that 

closely resemble those of fixed-wing aircraft. Many of the older and newer rotorcraft do not 

lend themselves to undersurface markings (e.g., Schweizer 300, Erickson S-64, Hiller OH-
2

23, Hughes 269, MD-520N). Aircraft that participate in Part 133-External-Load Operations, 

Part 137-Agricultural Aircraft Operations and Aerial advertising, have equipment attached 

that would obscure or interfere with the display of bottom surface marks.

Further, requiring dual-marking requirements would impose an undue economic burden on 

rotorcraft owners, particularly those who attach equipment that would obscure the bottom 

surface marks. Additional costs may be incurred by those rotorcraft operators having to 

modify paint schemes to accommodate the bottom surface marks.

In granting any petition for rulemaking to the provisions of part 45, the FAA must consider 

the primary reason for which part 45 was amended (Amendment 45-9 and Amendment 45-

15) to require at least 12-inch high, or as high as practicable, registration marks on fixedwing and rotorcraft aircraft. It was determined by the FAA, Department of Defense (DOD), 

and the Drug Enforcement Administration (DEA) that 12-inch registration numbers on the 

side of the fuselage provide for better air traffic control and flow at airports (visual 

identification of aircraft), and assist other government agencies involved in law enforcement 

and military activities in areas such as illegal drug-trafficking and national security for better 

air-to-air identification. The FAA has determined that the display of at least 12-inch high 

marks on the sides of aircraft is most effective for aircraft identification purposes.

In consideration of the foregoing and pursuant to the authority contained in 49 U.S.C. 40113 

and 44701, delegated to me by the Administrator, your petition for rulemaking is hereby 

denied.

Sincerely,

/s/

Frank P. Paskiewicz

Acting Deputy Director, Aircraft Certification

 Service