A typical AGL System comprised of three main parts:
AGL Circuits & Patterns, which actually provide the visual guidance to the pilot based on the 4C’s
AGL Substations.
Airfield Lighting Control & Monitoring System (ALCMS)
These parts may change more or less depending on the feeding concept or the airfield category. For instant in Solar based AGL lights, you wont have AGL circuits, and surely no AGL substations are required, also the control system will be totally different, however, Solar based AGL still developing and cant be used as a sole source of guidance in High Category Airfields.
ICAO regulations pertaining to AGL are stipulated in ( Aerodrome Design Manual, Annex.14) , Visual Aids Design Manual (Doc 9157, Part.4) and Electrical Systems Design Manual (Doc 9157, Part.5)
ICAO Regulations are classified in two types:
Wherever the word “Shall” is used , the following clause is considered as a mandatory Requirement
Wherever the word “Should” is used, the following clause is considered as Recommendation.
AGL systems have different requirements based on the Airfield Category.
Each category shall have a number of Requirements & Recommendations that need to be reflected on the AGL circuits, AGL substations & Remote control system.
As the airfield category change, the parameters of the airfield 4C’s change.
This includes :
Configuration
The need to have a specific AGL circuits or not.
The pattern of existing AGL systems.
Spacing between AGL units.
Color of AGL lights may change as the category changes.
Coverage: Aiming angle and AGL units calibration may change based on Airfield category like what happens at Approach lighting.
Candela: The need to have some more High Intensity lights changes as the airfield category change.
In addition to important changes in the AGL substation which mainly affect the Switching-Over time in case of main power interruption, as each category has a maximum allowable switching-over time, for which AGL substations of airfield categories need to be equipped with different devices to achieve the required switching-over time.
AGL Patterns:
1. Approach Lighting
Runway End Identification Lighting System (REILS)
Simple Approach
Precision Approach CAT I
Precision Approach CAT II
Precision Approach CAT III
Precision Approach Path Indicator (PAPI)
Rotating Beacon
2. Runway Lighting
Threshold & Wing-bar Lights
Touchdown zone lights
Runway Edge Lights
Runway Centerline Lights
Runway End Lights
Rapid Exit Taxiway Identification Light (RETIL)
Runway Stopbar Lights
Runway Guard Lights (Wig-Wag)
Runway Lead-in Lighting System
3. Taxiway Lighting
Taxiway Edge Lights
Taxiway Centerline Lights
Taxiway Stopbar Lights
Intermediate Holding Position Lights
4. Apron Lighting
Apron Perimeter Lights
Aircraft Stand Maneuvering Guidance Lights (Or Apron Lead-In Lights)
5. Guidance Signs
Information Guidance Signs
Mandatory Guidance Signs
AGL circuits or loops are build out of :
AGL Primary circuits
AGL Secondary circuits
Pit Fit-outs (where shallow base lights are used)
AGL Counterpoise and Earthing System
AGL Infrastructure
AGL Substation Shall have the following electrical components:
Main Power Source
Secondary Power Source
Constant Current Regulators (CCR’s)