What do red terminating bars signify in approach lights?

Red terminating bars in approach lights are critical markers for pilots as they approach a runway for landing. Specifically, these bars indicate that the flight path is clear to descend below 100 feet above the touchdown zone elevation. When pilots see red terminating bars, they understand that they are nearing the runway and should be prepared for landing, as it signifies they are at an appropriate altitude with sufficient visibility and no immediate obstructions in their approach.

This function is especially important during low visibility situations when the pilot relies on these markings for safe descent and landing. The presence of red bars signals the transition from the approach lighting system to the runway surface, which is vital for ensuring safe landing procedures.