Precision Approach Path Indicator

The Precision Approach Path Indicator (PAPI) is a visual system next to the touch-point on a runway. The purpose of the system is to lead a plane in correct approach. The PAPI creates ray of light which gives pilot information about his actual height.

Principle:

• If plane is over correct approach line, pilot will see 3 white lights and 1 red. If he is higher, he will see all lights in white.
• If plane keeps correct approach, pilot will see 2 white lights and 2 red. The right line is in the angle 3 degrees from axis of airport.
• If plane is under correct approach line, pilot will see 3 red lights and 1 white. If he is lower, he will see all lights in red.

The rules about the parameters are written in standard ANNEX 14 ICAO. The brochure contains more specific information about intensity of ray, location where we can get device etc.

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  The PAPI device

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  Principle of PAPI indication

Precision Approach Path Indicator Media

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  The PAPI can be seen to the right (non-standard) side of the runway. The aircraft is slightly below the glideslope.

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  Schematic diagram of longitudinal section*1 = Axis datum2 = Light source3 = Red filter4 = Lenses5 / 6 = Light beam- white/red

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  Comparison of PAPI, VASI, and OLS meatball and datum lights (not to scale)

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  Individual precision approach path indicator