Definition
The standardized arrangements of lights installed on the ground leading to a runway threshold, designed to help pilots transitioning from instrument flight to visual flight identify the runway environment and align with the landing surface during the final stages of an approach. Different configurations (such as ALSF-1, ALSF-2, MALSR, MALS, ODALS, and SSALR) provide varying levels of guidance depending on the runway's approach category and the precision of the instrument procedure served.
Plain English
These are the patterns of lights laid out on the ground before a runway. They help a pilot finishing an instrument approach see and line up with the runway. There are several standard layouts, each with its own pattern and name, used at different airports.
Context Anchor
Seen on instrument approach charts and during the final part of an approach, especially at night or in reduced visibility.
Derivation
Approach means to come nearer. Configuration comes from Latin roots meaning to form or shape together. That helps here because the lights are useful not just as individual lights, but because their arranged shape gives the pilot information.
Why Pilots Care
Knowing the exact configuration tells the pilot how far the lights extend and what minimum visibility is required to continue the landing.
Grounding Statement
Near the runway, the light pattern gives the pilot a visual path from the instrument portion of the approach to the runway itself.
Intuition Check
Do not read configuration as meaning any random group of lights. In this context, it means a planned, approved runway light pattern with a specific purpose.
Example Sentence 1
The pilot reviewed the approach lighting configuration for the runway before starting the descent, knowing the MALSR layout would give a clear visual lead-in to the threshold.
Example Sentence 2
Different approach lighting configurations affect the decision height at which the runway must be in sight.