What does the back course marker indicate?

The back course marker serves a specific purpose in navigation during instrument approaches. It indicates the Final Approach Fix (FAF) on approaches that utilize the back course. In this context, the back course approach is one where the aircraft is flying towards the navigational aid (such as a localizer) from the opposite direction of the published final approach course. The back course marker is crucial for pilots as it signals the point at which they should make their final descent decisions, ensuring they are positioned correctly for a safe landing.

Understanding the role of the back course marker is vital for pilots conducting instrument landings, as it helps them maintain the correct approach path and ensures situational awareness in potentially challenging conditions.