How wide must the letters or numerals in a registration number be compared to the height?

The correct answer is that the width of letters or numerals in a registration number must be two-thirds of the height. This requirement is specified to ensure that registration numbers are clearly legible and easily identifiable on aircraft. By establishing a standard that the width is two-thirds of the height, it helps maintain consistency in the appearance of these markings, thus enhancing visibility from a distance.

This standard is important not only for operational clarity but also for regulatory compliance, allowing for quicker identification of aircraft during inspections and operations. Ensuring uniformity in the size and proportion of these characters plays a vital role in aviation safety.