If an arriving aircraft is inside the ILS Outer Marker, under which weather condition would you not authorize vehicles to operate in the ILS critical area?

If an arriving aircraft is inside the ILS Outer Marker, under which weather condition would you not authorize vehicles to operate in the ILS critical area?

• A. Ceiling greater than 2000 feet and visibility greater than 5 miles
• B. Ceiling less than 800 feet or visibility less than 2 miles
• C. Ceiling exactly 1000 feet and visibility 3 miles
• D. Ceiling 2000 feet and visibility 1 mile

Answer: (B)

When an arriving aircraft is inside the ILS Outer Marker, vehicles in the ILS critical area must be restricted if weather falls to the point that the approach protection could be compromised. The limiting conditions are a ceiling below 800 feet or visibility below 2 miles. If either of these is true, you would not authorize ground vehicles to operate in the ILS critical area. This threshold is chosen because lower ceilings or poorer visibility reduce the pilot’s ability to maintain a stable approach and can increase the risk of ground vehicles interfering with the ILS signals or the approach path. The other scenarios either show weather that meets or exceeds those minimums (which would generally allow authorization) or, in practice, would still be assessed against the same minimums.

When an arriving aircraft is inside the ILS Outer Marker, vehicles in the ILS critical area must be restricted if weather falls to the point that the approach protection could be compromised. The limiting conditions are a ceiling below 800 feet or visibility below 2 miles. If either of these is true, you would not authorize ground vehicles to operate in the ILS critical area.

This threshold is chosen because lower ceilings or poorer visibility reduce the pilot’s ability to maintain a stable approach and can increase the risk of ground vehicles interfering with the ILS signals or the approach path. The other scenarios either show weather that meets or exceeds those minimums (which would generally allow authorization) or, in practice, would still be assessed against the same minimums.