𝐏𝐫𝐞𝐜𝐢𝐬𝐢𝐨𝐧 𝐀𝐩𝐩𝐫𝐨𝐚𝐜𝐡 𝐏𝐚𝐭𝐡 𝐈𝐧𝐝𝐢𝐜𝐚𝐭𝐨𝐫 (𝐏𝐀𝐏𝐈)

Precision Approach Path Indicator

🛩️A precision approach path indicator (PAPI) is a visual aid that provides guidance information to help a pilot acquire and maintain the correct approach (in the vertical plane) to an airport or an aerodrome.

🛩️It is generally located on the left-hand side of the runway approximately 300 meters beyond the landing threshold of the runway.

🛩️The ratio of white to red lights seen is dependent on the angle of approach to the runway.

🛩️Above the designated glide slope a pilot will observe more white lights than red.

🛩️At approaches below the ideal angle more red lights than white will be seen.

🛩️For the optimum approach angle the ratio of white to red lights will remain equal throughout, for most aircraft, the exceptions being the Boeing 747 and now retired Concorde.

🛩️With the 747, because the cockpit is approximately 20 feet behind the nose and much higher than other aircraft, the flight crew in a 747 will typically see one red and three white lights when they are on the glide slope.

🛩️The aircrew of Concorde would see four white lights as the Concorde's approach angle was higher than traditional aircraft.

🛩️These lights are visible from 5 miles in normal sunlight days, and upto 20 miles at night.

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