What feature distinguishes REILs lighting at the end of a runway?

Runway End Identifier Lights (REILs) are designed specifically to alert pilots to the presence and location of a runway. The distinctive feature of REILs is that they emit flashing colored lights, which are typically white, positioned at both sides of the runway threshold. These lights provide a visual indication of the runway’s end at night or in conditions of reduced visibility.

The flashing characteristic is vital as it enhances their visibility and helps pilots identify the runway in a crowded visual environment. It's also important to note that the colors and steady or flashing nature of lights are carefully chosen to avoid confusion with other airport lighting, such as runway lights and taxiway indications. This helps in delineating the runway environment clearly.

Understanding the function and design of REILs can significantly improve situational awareness for pilots, especially during approach and landing phases of flight.