What do red terminating bars signify in approach lights?

Red terminating bars in approach lights serve a critical function by indicating that pilots must be able to see these lights in order to descend below 100 feet above the touchdown zone elevation. This visual cue is essential for ensuring that an aircraft is on the correct approach path to the runway and that the pilot has adequate visual references to continue safely with the landing.

The presence of red terminating bars signifies that the runway is either very close or that the approach is about to end, reinforcing the pilot's situational awareness and decision-making as they prepare for landing. If these lights are not visible, it signals to the pilot that they should not descend further, as the conditions may not be conducive to a safe landing.

Understanding this function helps pilots adhere to safe landing protocols, making these lights vital components of the approach lighting system used in aviation.