Obstacle Free Zone / APCH signs are part of which category?

• A. Mandatory Instruction Signs
• B. Runway designation signs
• C. No Entry Signs
• D. Direction Sign Array

Answer: (A)

The main idea is how airport signs are categorized by their function. Obstacle Free Zone and APCH signs define a boundary that pilots must not cross without explicit clearance, which is exactly what mandatory instruction signs convey. These signs are red with white lettering and are used to enforce critical boundary or hold requirements, such as not entering the obstacle free zone or approach path. The other sign categories serve different purposes: runway designation signs identify runways, no entry signs prohibit access in a general sense, and a direction sign array simply guides where to go. So, the OFZ/APCH signs belong to theMandatory Instruction Signs category because they indicate a boundary that requires clearance to proceed.