Compliances (Current Editions)

FAA: AC 150/5345-28 and Engineering Brief No. 67, ETL Certified
ICAO: PAPI Annex 14, Volume 1 (Current Edition)
Canada: PAPI / APAPI Transport Canada TP 312 par. 5.3.16.12 and Appendix 5B, Figure B-19
CASA: PAPI Part 139
EASA: PAPI/APAPI EU No 139/2014

Theory of Operation Overview

The Airport Lighting Company LED PAPI provides beneŠcial visual approach slope guidance to assist the pilot of an aircraft in Œying a stabilized approach. The FAA Type L-880 PAPI system consists of 4 Light Housing Assemblies (LHA) located adjacent to the origin of the glide path. Each LHA is installed at an o“set from the desired glide path, which is midway between the central pair of LHAs. The outer pair are slightly more o“set from the glide path than the inner pair. This configuration provides
an increasing number of white signals as the incoming aircraft deviates above the intended glid path, and an increasing number of red signals as the incoming aircraft deviates below the desired glide path. An approach along the desired glide path will yield two red signals and two white signals. The FAA Type L-881 PAPI system consists of 2 LHAs installed at angles equally above and below the glide path. An approach along the desired glide path will yield one red signal and one white signal. The ALC LED PAPI includes a mercury-free electronic failsafe inclinometer to prevent operation if an LHA is raised 0.5 degrees or lowered 0.25 degrees from its set angle.

Application

The L-880(L) LED PAPI and L-881(L) LED APAPI provide visual glide path guidance to pilots during the final approach to landing. The system projects a composite beam consisting of red and white light sectors separated by a sharp transition zone. The pilot interprets the color combination seen from the aircraft to determine if the aircraft is on, above, or below the correct glide path.

Key Features

- Estimated Life LEDs > 150,000 hours at full intensity
- LED Display indicates angle and status without opening
- Redundant Digitally Controlled Lens Heaters
- 89 Max VA per light unit with heater active
- Compact and Light Weight (less than 40 lbs per LHA)
- Only one Liquid Tight conduit per light unit
- Optical Lens hardened against sandblast
- Optical Chamber Sealed against moisture and dust
- Streamlined mounting leg assemblies
- Retrofits directly on ALC incandescent installations
- External Junction Box (PDU) configurations available
- FAA Class: -55° C

 

 

Glide Path Indication – L-880(L) PAPI (4-Unit System)

Two units on each side of the runway provide a total of four light beams.

On glide path: The pilot sees two red and two white lights (2 red / 2 white).

• Too high: The pilot sees three or four white lights (3 or 4 white).
• Too low: The pilot sees three or four red lights (3 or 4 red).

The transition from red to white is sharp and occurs over approximately 2.5 to 3 minutes of arc. The nominal glide path angle is adjustable between 2.8° and 4° above the horizontal.

Glide Path Indication – L-881(L) APAPI (2-Unit System)

A single unit on each side of the runway provides a total of two light beams.

On glide path: The pilot sees one red and one white light (1 red / 1 white).

• Too high: The pilot sees two white lights (2 white).
• Too low: The pilot sees two red lights (2 red).

The beam geometry and transition characteristics are similar to the L-880(L) but with fewer units.

Adjustment and Compliance

The LHA is mounted on adjustable legs that allow precise tilting to set the desired glide path angle.
All photometric performance complies with FAA AC 150/5345-28, EB 67, ICAO Annex 14, and other listed standards.
Intensity is automatically adjusted based on ambient light conditions or manual setting via DIP switches.

 

Airport Lighting Company | L-880(L)/L-881(L) Precision Approach Path Indicator (PAPI)