When is the ILS critical area hold short requirement in effect?

The ILS critical area hold short requirement is specifically tied to the visibility conditions surrounding the runway and the Instrument Landing System (ILS). When visibility is less than 800-2, it is critical to ensure that any aircraft or vehicle does not encroach upon the ILS critical area. This is because the ILS provides guidance to aircraft approaching for a landing, and any interference can lead to erroneous signals, increasing the risk of accidents. Therefore, the hold short requirement is enforced in lesser visibility conditions to maintain the integrity and safety of the ILS operations.

Normal weather conditions, a closed runway, or heavy traffic periods do not specifically necessitate the hold short requirement in the same way. While other factors may influence airport operations, they do not directly pertain to the safety parameters established for ILS critical areas under reduced visibility scenarios.