Definition
An approach lighting system installed at the runway threshold that provides visual guidance to pilots arriving on an instrument approach. It is a shorter, simpler version of a full approach lighting system, and it includes sequenced flashing lights that fire in rapid succession toward the runway to lead the pilot's eye to the threshold.
Plain English
A row of lights leading up to the start of the runway, with extra lights that flash one after another like a moving arrow pointing the pilot toward the runway. It is a shorter, simpler version of the longer lighting systems used at busier airports.
Context Anchor
Pilots encounter SSALF in airport lighting information, instrument approach charts, and NOTAMs describing runway lighting equipment.
Derivation
The name describes itself: 'simplified' means a reduced version, 'short' means it covers a shorter distance than a full system, 'approach lighting' means lights that guide an arriving aircraft, and 'sequenced flashers' are the lights that fire one after another in sequence.
Why Pilots Care
Provides positive runway identification and alignment cues in reduced visibility, reducing the risk of runway incursion or misalignment on final approach.
Analogy
It works like a lighted path, with flashing lights drawing your eyes in the direction you need to go.
Intuition Check
Do not read “simplified” as meaning unimportant or casual. Here it means a less extensive version of an approach lighting system, still installed for a specific runway guidance purpose.
Example Sentence 1
The approach plate showed that Runway 27 was equipped with SSALF, so the pilot expected to see flashing lights leading to the threshold once below the clouds.
Example Sentence 2
During the ILS approach the SSALF lights became visible at two miles, confirming the correct runway alignment.