What are PAPI Lights?
What are PAPI lights? PAPI is the abbreviation of Precision Approach Path Indicator. PAPI Lights consist of 4 equidistantly set wing row lights with rapidly changing colors of multi-bulb lamps. The 4 lamps face the aircraft approaching for landing at different angles. The principle of light refraction is used to enable pilots flying along different glide slopes to observe lamps of different colors.