What does an ALCMS record?
Every command, state change and alarm is stamped with a time and a source, so the system can show what is happening now and prove what happened before.
ALCMS event logging is the automatic recording of what happens in the control system. Events come from operators and ATC (switching a circuit, changing an intensity step), from CCRs and field controllers (status changes and alarms), from the network (a link lost or restored) and from the system itself (log-ins, configuration changes). The server adds a timestamp and a source and stores each entry in the event log.
The alarm list shows what needs attention now. The event log is the wider history behind it. Engineers use it to spot repeated or intermittent faults, investigators use it to see who commanded what and when, and managers use it for availability and response-time reports. For this to work, clocks must be synchronised and the log must be protected from editing or deletion.
Frequently Asked Questions
Q1What is an ALCMS event log?
A time-ordered record of what happened in the control system: operator commands, circuit and intensity changes, alarms, equipment status changes, communication faults and system actions such as log-ins or configuration changes. Each entry carries a timestamp, a source and a description.
Q2What should a log entry contain?
At minimum a timestamp, the source (circuit, CCR, controller or user), the event type, a severity and a description. Many systems also record the operator, the previous and new value, and whether and by whom an alarm was acknowledged.
Q3Why do clocks matter for event logs?
Events from many controllers and servers are only comparable if they share one time source. Unsynchronised clocks make it hard to put events in the right order when investigating an incident, so systems normally synchronise to a common time reference.
Q4How is the event log used?
Operators use the live alarm and event list. Engineers use history to find repeated or intermittent faults and plan maintenance. After an incident, the log helps show who commanded what and when. Managers use it for availability and response-time reporting.
Q5How long should logs be kept?
That is set by the airport, the regulator and the project specification, not by this page. Retention, backup and protection against editing or deletion should be defined at design stage and checked in service.
Q6Is the log the same as the alarm list?
No. The alarm list shows faults that need attention now. The event log is the wider history, which includes alarms but also normal commands and state changes.
See It. Understand It. Then Learn How to Engineer It.
Recognising an AGL system visually is the first step. The next step is knowing how to design, install, test, commission and maintain them correctly.
Build Practical AGL Engineering Skills
Go deeper with structured training from Precision AGL Academy, covering:
Learn how each light, sign and circuit works as part of a complete airport lighting system, not just as an isolated diagram.