Approach lighting system

Modern approach lighting systems are highly complex in their design and significantly enhance the safety of aircraft operations, particularly in conditions of reduced visibility.

Approach lighting systems provide additional cues that bear a known relationship to the runway itself and help pilots to judge distance and alignment for landing.

After World War II, the U.S. Navy and United Airlines worked together on various methods at the U.S. Navy's Landing Aids Experimental Station located at the Arcata–Eureka Airport, California air base, to allow aircraft to land safely at night and under zero visibility weather, whether it was rain or heavy fog.

All approach lighting systems in the United States utilize a feature called a decision bar.

Approach lighting systems are designed to allow the pilot to quickly and positively identify visibility distances in Instrument meteorological conditions.

[4] Sequenced flashing lights and RAIL do not extend past the Decision Bar to avoid distracting the pilot during the critical phase of transitioning from instrument to visual flight.