What is the correct practice for using numerical values in a transmission?

• A. Always spell out numbers in words.
• B. Use digits for numbers but never spell out numbers.
• C. Use digits for numbers and units, but avoid spelling out numbers.
• D. State numbers clearly using digits; spell out large numbers if needed for clarity.

Answer: (D)

Using digits to convey numeric values in a transmission provides exact quantities and minimizes misinterpretation when the message is spoken or heard over a radio channel. Pair the number with the appropriate unit so everyone knows what is being measured, whether it’s altitude, speed, distance, or time. The rule also allows spelling out large numbers when that spelling improves understanding—long sequences of digits can be harder to catch correctly in a noisy line, so saying the number in words can reduce confusion. For example, “Altitude 12,000 feet” clearly communicates the magnitude and the unit; if the situation is prone to mishearing, you could clarify by saying “Altitude twelve thousand feet.” In essence, digits ensure precision and speed, with the option to spell out large numbers when needed for clarity.