What should be marked on all FOD containers?

Marking FOD (Foreign Object Debris) containers with "FOD" written in contrasting letters is essential for clear identification. This practice ensures that anyone handling the container can quickly recognize it as an area designated for collecting potential hazards. Distinctive labeling is particularly important on airfields where the safety of aircraft operations is a top priority. In high-traffic areas, clear signage helps prevent accidental exposure to debris that could cause severe damage to aircraft or engines.

While the other options denote various considerations related to safety and operations, they might not convey the specific focus on identifying the container's purpose as effectively. For instance, “FOD Check Required” emphasizes an action rather than the nature of the container itself, which could lead to confusion. "Aircraft Maintenance Only" implies a restriction on who can access the container and could mislead personnel about its intended use. "Caution: Do Not Open" raises concerns about security or hazardous content but does not address the importance of recognizing that the container is specifically for FOD, which is crucial to maintain an organized and safe working environment on the airfield.