Most aircraft are required to have N numbers, or "markings," at least 12 inches high. Here is a summary of the rest of the required physical attributes of the markings, as well as a list of those aircraft exempt from the 12-inch requirement.
Click here for information about changing or reserving your N number.
Applicable Code of Federal Regulations (CFR) 14 CFR Part 45, Identification and Registration Marking, prescribes the requirements of aircraft registration numbers.
For most fixed-wing aircraft, the marks must meet the following requirements:
Note: No person may operate an aircraft under the exceptions listed below if one or more of the following apply:
The following aircraft may display marks at least 2 inches high:
The following aircraft may display marks at least 3 inches high:
All aircraft penetrating an air defense identification zone (ADIZ) must have markings at least 12 inches high, at least temporarily. Using 2-inch-wide electrical tape is an acceptable method to temporarily display the aircraft's registration markings.
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