What color combination signifies mandatory instructions at an aerodrome?

The color combination that signifies mandatory instructions at an aerodrome is white on red. Mandatory instruction signs are essential for the safe operation of aircraft on the ground, and they convey critical information that must be followed by pilots and ground personnel. The white text on a red background clearly indicates the importance of the instruction, ensuring that it stands out and captures the attention of those operating in the vicinity.

Each color combination in aerodrome signage serves a specific purpose. For example, yellow on black is used for warning signs, while black on orange typically indicates a temporary situation that may require special attention or caution. The use of white and green is generally associated with destination signs. By understanding the meaning behind these color combinations, pilots can better navigate the airfield and comply with essential regulations.