What is SCADA?
SCADA is the supervisory layer that collects status and alarms from the field controllers, shows them to operators, keeps the history and passes supervisory commands down.
SCADA — supervisory control and data acquisition — is the layer that watches the whole airfield lighting system at once. A SCADA server polls the PLCs and CCRs for status and readings, raises and lists alarms, and keeps a historian of events, operator actions and trends. The HMI clients at the tower and maintenance station are its screens, and a supervisory command from an operator is passed down through the server to the field controllers.
SCADA supervises; the PLCs still run the real-time logic and drive the equipment, so a SCADA failure does not by itself switch the lights off. The ALCMS is commonly built on SCADA software, and servers are often redundant with a standby. If the server or network fails, the screen can be out of date and the real status is checked at the CCR or in the field. Because it is networked, access control and security are part of the design.
Frequently Asked Questions
Q1What does SCADA stand for and what does it do?
SCADA means supervisory control and data acquisition. In an airfield lighting control system it is the supervisory layer that collects status, alarms and readings from the PLCs and CCRs, shows them to operators on the HMI, keeps a record of events and trends, and passes supervisory commands down to the field controllers.
Q2How is SCADA different from a PLC?
A PLC runs the real-time control logic close to the equipment, repeating its scan cycle continuously. SCADA sits above it: it gathers data from many PLCs, presents the whole airfield on one system, stores the history and sends supervisory commands, but it does not replace the controllers that drive the equipment.
Q3How do SCADA, ALCMS and the HMI relate?
The ALCMS is commonly built on SCADA software. The SCADA server holds the data and logic for supervision, the HMI is the screen operators use to see it and send commands, and the PLCs and CCRs do the work in the field. The exact split depends on the manufacturer and the project.
Q4What does the SCADA record, and why does it matter?
It normally logs alarms, events, operator commands and readings with time stamps. That history helps find the cause of a fault, shows trends such as a circuit slowly degrading, and supports review after an incident or a maintenance visit.
Q5What happens if the SCADA server or network fails?
That depends on the design. Servers are often redundant, and the PLCs and local control at the CCR remain available, but the screen can become out of date. Check the real status at the CCR or in the field, tell ATC as the procedure requires and follow the failure flow.
Q6Why does SCADA security matter?
Because it is networked, access control, user levels and network protection are part of the design, and only authorised personnel should change settings or commands. Software changes follow the airport's change-control procedure, with the lights verified afterwards.
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