What is the purpose of the glide slope in an ILS approach?

The glide slope is an essential component of the Instrument Landing System (ILS) that provides vertical guidance during an approach to landing. Its primary purpose is to ensure that an aircraft descends at the correct angle towards the runway, typically around 3 degrees. This specified descent angle helps pilots achieve a safe and stable approach, allowing for a precise landing without the need for visual reference until they are very close to the runway.

By following the glide slope indication, pilots can accurately maintain the appropriate vertical profile while adjusting their descent rate and altitude. This capability is crucial, especially in low-visibility conditions, where visual references are limited. Maintaining the proper glide slope not only contributes to a successful landing but also enhances safety by reducing the risk of landing too high or too low on the approach path.

In contrast, other options focus on different aspects of flight that the glide slope does not address, such as aircraft speed, lateral guidance, or wind direction. These elements are influenced by separate instruments and systems in the cockpit, underscoring the glide slope's specific role in providing vertical assistance during the landing phase.