Question

What are the two airfield requirements for a CAT II ILS?

Answer 1

The two key airfield requirements for a CAT II ILS are an Approach Lighting System with sequenced flashing lights, and sufficient runway visual range for low-visibility landings.

Step-by-step explanation:

The two airfield requirements for a Category II (CAT II) Instrument Landing System (ILS) are an Approach Lighting System (ALS) with sequenced flashing lights, and a runway visual range (RVR) that allows a minimum range of visibility for pilots. The airfield should also be equipped with necessary navigation aids to support precision landing and have standard operational procedures in place for CAT II operations. These facilities and procedures are crucial for safe and efficient aircraft operations during low visibility conditions that can occur due to fog, rain, or other weather-related factors.

Answer 2

The two airfield requirements for a CAT II ILS (Category II Instrument Landing System) are the Runway Visual Range (RVR) and Decision Height (DH).

Step-by-step explanation:

CAT II ILS is a precision approach and landing system designed to provide guidance to an aircraft for a safe and accurate approach and landing in reduced visibility conditions. The two crucial airfield requirements for CAT II ILS are the Runway Visual Range (RVR) and Decision Height (DH).

Firstly, the Runway Visual Range (RVR) is the horizontal distance a pilot can see down the runway from the approach end. For CAT II ILS, the RVR minimums are typically lower than those for CAT I ILS, allowing for operations in lower visibility conditions. These minimums are measured in feet, and a CAT II approach might require an RVR as low as 1200 feet.

Secondly, the Decision Height (DH) is the altitude at which a pilot must decide whether to continue the approach or execute a missed approach if the required visual references are not established. For CAT II ILS, the DH is lower compared to CAT I, often in the range of 100 to 200 feet above the runway. Pilots rely on the ILS guidance system to descend to the Decision Height before making a visual decision to land or abort the approach.

In summary, the CAT II ILS airfield requirements of RVR and DH are critical for ensuring safe and reliable operations in reduced visibility conditions. The lower minimums for RVR and DH in CAT II compared to CAT I enable aircraft to perform precision approaches and landings in weather conditions that would otherwise require diversion or delay.