ILS critical areas near active runways become active when weather is below which conditions?

• A. Weather conditions below 800 feet ceiling and/or 2 miles visibility.
• B. Weather below 1,000 feet ceiling and 3 miles visibility.
• C. Weather below 500 feet ceiling and 1 mile visibility.
• D. Weather below 2,000 feet ceiling and 4 miles visibility.

Answer: (A)

The ILS critical area is protected when weather drops to a level where instrument approaches are being used and signal integrity could be affected. Specifically, this protection is activated when conditions are below 800 feet ceiling and/or 2 miles visibility. The “and/or” means that if either the ceiling falls below 800 feet or the visibility falls below 2 miles, ATC activates protection of the critical area to prevent interference with the ILS signals from other aircraft or ground traffic.

When this area is active, pilots should avoid entering it unless explicitly cleared by ATC. This helps ensure that aircraft on or near the runway and approach path do not disrupt the ILS signals, preserving safe and reliable guidance for approaches.

The other listed minima don’t align with the standard activation threshold for ILS critical areas, which is why they’re not correct.