Precision approach path indicator systems (PAPIs) effective in providing approach slope guidance for aircraft approaching an airport runway are provided. Such PAPIs include a plurality of light assemblies positioned on or in proximity to an airport runway and structured or configured to be effective in providing approach slope guidance light signals to a pilot of an aircraft approaching a runway. Each light assembly includes a light source comprising light emitting diodes (LEDs), preferably a first array of LEDs and a second array of LEDs.