Poor visibility during dense fog poses significant challenges for pilots and hampers flight operations. To mitigate this, aircraft use a ground-based navigation system called the Instrument Landing System (ILS). The ILS provides directional guidance and descent signals to help pilots land safely.
The ILS consists of several components, including the localiser, glide path, markers, Distance Measuring Equipment (DME), and runway lighting systems. The localiser guides the pilot laterally, while the glide path component ensures proper descent angle for a safe landing. The DME provides slant distance to the aircraft with respect to the touchdown point.
Additionally, lighting systems and visual aids are deployed on the runway to assist pilots in seeing when they approach the decision height or missed approach point. Warnings are sounded if pilots deviate from the centreline, either undershooting or overshooting it. Radar instruments are also used to ensure stable descent and designated aircraft path despite low visibility.
A pilot’s skill and training experience play a critical role in making real-time choices during landing operations under low-visibility conditions. Airport infrastructure, such as ILS Category 3 certification (CAT 3), is essential for supporting safe landings. Delhi’s Indira Gandhi International Airport has four CAT 3 compliant runways, which enables pilots to land safely even in dense fog.
Source: https://www.hindustantimes.com/india-news/how-do-aircraft-land-under-zero-visibility-conditions-during-dense-fog-101735989521511.html