Final answer:
In zero visibility fog, using radar instruments, similar to those used by air traffic controllers in cloudy weather, is the recommended safety action.
Step-by-step explanation:
The recommended action in very dense (zero visibility) fog is similar to the method used by air traffic controllers during bad weather conditions. When visibility is compromised to the point where it's difficult to see, it's advised to use technology, such as radar instruments, to navigate safely. Just as controllers would use radar to locate and guide incoming planes that cannot be seen with the eye during heavy cloud cover or smog, in situations of zero visibility due to dense fog, the same approach of relying on technological instruments is recommended for safety.