What does the inner marker beacon indicate and what is its color?

The inner marker beacon is part of an instrument landing system, particularly for precision approaches such as Category II approaches. Its primary function is to indicate that the aircraft is at or nearing decision altitude (DA). The decision altitude is a critical point during an approach, informing pilots that they need to make a decision whether to continue the approach or execute a missed approach based on visual references.

The inner marker beacon emits a white light, which is consistent with its role in providing visual confirmation for pilots as they descend through the approach. In the context of Category II approaches, which allow for lower visibility minimums, the inner marker is crucial for ensuring that pilots are aware of their location in relation to the runway.

This understanding aligns with the purpose and standard color coding of the inner marker beacon, helping pilots effectively navigate during critical phases of flight.