Whenever an arriving aircraft is inside the ILS Outer Marker (OM) or the fix used in lieu of the OM, do not authorize vehicles/aircraft to operate in the ILS critical area when conditions are a reported ceiling ___ feet or visibility ___ miles.

• A. less than 800; less than 2
• B. less than 1,000; less than 3
• C. 800; 2
• D. 1,000; 3

Answer: (A)

The key idea is protecting the ILS critical area during the final approach phase, specifically when an arriving aircraft is inside the Outer Marker or the fix used in lieu of the OM. In that situation, traffic in the critical area must be restricted if the weather falls below certain minima to keep the ILS signals reliable for the approaching airplane.

The correct choice uses the thresholds “less than 800 feet” for ceiling and “less than 2 miles” for visibility. If either condition is below those values, you should not authorize vehicles or other aircraft to operate in the ILS critical area. This exact phrasing ensures you’re acting only when weather is sufficiently poor to risk interference with the ILS guidance, which is most protective during the OM segment.

Other options either imply different minima or use inclusive values (such as equal to the threshold) that don’t align with the standard rule. This is why the lower, “less than 800 feet” and “less than 2 miles” formulation is the correct guidance.