An amateur-built aircraft recently registered in the U.S. with a maximum speed of 180 mph requires registration markings of what size?

For an amateur-built aircraft registered in the U.S. with a maximum speed of 180 mph, the Federal Aviation Administration (FAA) mandates specific sizes for registration markings. In this instance, the correct size for the registration markings is indeed 3 inches. The requirements dictate that the height of the letters for the registration number (N-number) must be at least 3 inches tall for aircraft that have a maximum speed of more than 100 knots (approximately 115 mph). This regulation ensures that the registration marking is visible and legible, which is crucial for identification purposes, especially for law enforcement and safety inspections.

Understanding the rationale behind these size requirements is important, as it aligns with safety guidelines that promote clarity and visibility of identification in various operational scenarios. Thus, for an aircraft like the one described, having registration markings with a height of 3 inches meets the FAA's operational standards and requirements.