Product Description

The PAPI(Precision Approach Path Indicator ) is a light array positioned beside the runway. It normally consists of four equi-spaced light units color-coded to provide a visual indication of an aircraft’s position relative to the designated glideslope for the runway.

The PAPI is usually located on the left-hand side of the runway at right angles to the runway center line. The units are spaced 9 meters apart with the nearest unit 15 meters from the runway edge. A PAPI can, if required, be located on the right-hand side of the runway. At some locations PAPIs are installed on both sides of the runway but this level of provision is beyond the requirements of ICAO. The light characteristics of all light units are identical.

Each light unit consists of one or more light sources, red filters and lenses. Each light unit emits a high-intensity beam. The lower segment of the beam is red, and the upper part is white. The transition between the two colours must take place over an angle not greater than three minutes of arc. This characteristic makes the color change very conspicuous, a key feature of the PAPI signal. To form the PAPI guidance signal, the color transition boundaries of the four units are fixed at different angles. The lowest angle is used for the unit furthest from the runway, the highest for the unit nearest to the runway. The designated glideslope is midway between the second and third light unit settings. Depending on the position of the aircraft relative to the specified angle of approach, the lights will appear either red or white to the pilot. The pilot will have reached the normal glidepath (usually 3 degrees) when there is an equal number of red and white lights.


Complience with standards

FAA 880/881, AC 150/5345-28



  1. ICAO 30° wide beam to obtain full advantage of MLS and to provide visual aid to touchdown. Circulating airflow minimises cold weather condensation effects on beam performance. Lens heaters included with lamp circuit to provide even dispersions of condensation
  2. Developed by Royal Aircraft Establishment at Bedford, UK
  3. Acquisition range: normal day 19km with met visibility 7.4km (see table)
  4. Easy maintenance whilst in service position. Lamp change via access hatches at the rear of the PAPI
  5. No special tools or instruments required for servicing. Optical bench not required
  6. Three leg mounting for ease of levelling and elevation setting with natural stability built in for high wind and jet efflux conditions
  7. Constant frangible facilities, regardless of mounting height
  8. Lenses protected from driving rain and splashing. No front window to keep clean Glare reduction as pilot approaches and passes threshold.


Electrical supply

Suitable for all normal series circuit systems of 6.6A, 8.33A, 12A, 16A or 20A. Can also be used on systems via voltage transformers 240V/120V 50/60Hz.


Fixture Position on Runway