What is an ALCMS?

The airfield lighting control and monitoring system — how operators command the lights from one screen and see their true status come back.

ALCMS OVERVIEW · CONTROL IT · SEE IT ONE SYSTEM · COMMANDS DOWN · FEEDBACK UP 1 OPERATOR Tower & maintenance Touch screens Select & watch ROLE: decides 2 ALCMS Server or PLC Logic & interlocks Event log ROLE: manages 3 NETWORK Fibre or Ethernet Often redundant Carries both ways ROLE: connects 4 FIELD UNITS At CCR or vault Read & drive CCRs Local control kept ROLE: acts 5 AIRFIELD CCRs & circuits Runway, taxiway Approach, signs ROLE: lights STATUS · ALARMS · FEEDBACK BACK TO THE SCREEN COMMANDS: ON · OFF · BRIGHTNESS STEPS · MODES COMMAND PATH SCREEN → ALCMS → CCR → LIGHTS Operator picks what to light and how bright FEEDBACK PATH LIGHTS → CCR → ALCMS → SCREEN Status shown true; faults raise alarms IF THE LINK FAILS, FIELD UNITS CAN STILL BE OPERATED LOCALLY SCHEMATIC · SIMPLIFIED · NOT TO SCALE · DESIGNS VARY
command path
status and alarm path
fallback
The Fact System overview

An ALCMS lets the operator control airfield lighting and monitor it at the same time. From a tower or maintenance screen, commands such as circuit selection and brightness step pass through the ALCMS and a communication network to field units at the CCRs, which drive the lights.

The path also runs the other way. Status and alarms from the CCRs and circuits return to the screen and are logged, so the operator sees what the field is really doing. The field units are normally designed so the lights can still be operated locally if the link is lost.

  1. Operator. Selects the lighting needed on a tower or maintenance screen.
  2. ALCMS. Applies logic and interlocks, and records the event.
  3. Network. Carries the command to the field, and the feedback back.
  4. Field units. Operate the CCRs and other equipment, and read their status.
  5. Airfield. The circuits light at the selected brightness.
  6. Feedback. Status is shown; any fault raises an alarm and is logged.
Purpose Control and monitor airfield lighting from one place
Main parts Operator stations, ALCMS server or PLC, network, field units
Controls Circuit on and off, brightness steps, operating modes
Monitors Circuit and CCR status, faults, alarms, event log
Users Air traffic controllers, maintenance staff
Reference ICAO Annex 14 Vol I Ch 8; ICAO Doc 9157 Pt 5; FAA AC 150/5345-56 (L-890 ALCMS); project specification
Schematic — simplified for clarity. Architecture, redundancy, equipment and fallback behaviour vary by airport and are set by the project specification, the applicable standard and the manufacturers’ documentation.
Start of Division 17 Entry 2 · AGL control architecture

Frequently Asked Questions

Q1What is an ALCMS in airfield ground lighting?

An airfield lighting control and monitoring system. It lets operators switch and dim airfield lighting circuits from one place, such as the control tower or a maintenance room, and see the status and alarms of the CCRs and circuits on screen.

Q2What does an ALCMS control and monitor?

It controls circuit on and off, brightness steps and operating modes. It monitors circuit and CCR status, faults and alarms, and often equipment such as stop bars, PAPI and signs, depending on the design.

Q3Who uses the ALCMS?

Air traffic controllers use it to select the lighting they need for the runway and taxiways in use. Maintenance staff use it to watch status, receive alarms and find faults, often with different access rights.

Q4What are the main parts of an ALCMS?

Operator stations or touch screens, the ALCMS server or PLC that holds the logic and records events, a communication network that is often redundant, and field units that connect to the CCRs and other lighting equipment.

Q5What happens if the ALCMS or its network fails?

The design decides. CCRs and field units are normally able to be operated locally, so the lights can still be controlled, but remote control and monitoring from the screens may be lost. The behaviour is checked during commissioning.

Q6How is the ALCMS overview different from the ALCMS interface?

This entry shows what the system is and how commands and feedback flow. The ALCMS interface entry in Testing and Commissioning covers how that link to the field equipment is proved, point by point, before handover.

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