What does the ILS critical area boundary sign identify?

The ILS critical area boundary sign is designed to identify the edge of the Instrument Landing System (ILS) critical area. This critical area is essential for ensuring that the signals from the ILS system are not disrupted by aircraft, vehicles, or other obstructions, particularly during low visibility conditions when precision approaches are being conducted. By marking the boundary, the sign helps ground personnel and pilots understand where the critical area begins, ensuring that operations within that region are conducted in a manner that maintains the integrity of the ILS signals. This identification is crucial for the safe and efficient operation of an airport, particularly when conducting precision approaches.