How is a CCR step selected?
Choosing which brightness step each regulator runs at. Read the conditions, apply the airport’s procedure, and give the pilot just enough light to see clearly.
A regulator offers a few fixed steps, but someone has to pick one, and keep picking as the weather and the light change. Step selection is that decision: bright enough to be seen, never so bright that it dazzles or wastes lamp life.
1Read the conditions
Two things matter most. Ambient light: a light that is easy to see at night is washed out in daylight, so day needs a higher step than night. Visibility: fog, rain and low runway visual range scatter the light, so poorer visibility pushes the step up. The two combine, so day with fog is the most demanding case.
| Condition | Step tends to be | Why |
|---|---|---|
| Bright day, good visibility | Higher | A bright background washes out a dim light, so it needs real intensity to stand out. |
| Day with fog or low RVR | Highest | Light must cut through both the background glare and the scattering. |
| Dusk or dawn | Middle | The background is fading, so the step comes down with it. |
| Clear night | Lower | There is little background light, and a high step would dazzle. |
| Night with fog or low RVR | Higher, as procedure allows | Fog scatters the light, but some procedures keep the top steps for a pilot request. |
2Apply the procedure, per lighting system
Approach, runway edge, centreline, touchdown zone and taxiway lights each have their own circuit and their own regulator, so each is selected on its own. The airport’s procedure, usually a table for each system, sets the step for each condition. A pilot request can raise or lower a step, and some procedures keep the very top steps at night for exactly that case.
3Select it and confirm it
The step is normally chosen by air traffic control or the airfield operator from the tower panel or the control and monitoring system. At the CCR it can be set locally, which is usually kept for maintenance and testing. Either way, confirm the change: the step should show on the display or control system, and the output current should match that step’s rated value.
- Read the conditions. Time of day, reported visibility or RVR, and weather.
- Find the procedure. Look up the step for each lighting system in the airport’s table.
- Select the step. From the tower panel or control system, or locally at the CCR when authorised.
- Confirm it. Check the step on the display and, where needed, the measured output current.
- Watch and adjust. Change the step as conditions change or when a pilot asks.
- Return control. After local work, put the CCR back to remote so the tower regains control.
| Term | Meaning |
|---|---|
| Intensity step | One of the fixed brightness settings, each a set output current |
| Step selection | Choosing which step a circuit runs at for the present conditions |
| RVR | Runway visual range, how far a pilot can see along the runway |
| Airport procedure | The table of steps for each lighting system and condition |
| Local / remote | Whether the step is set at the CCR or from the tower or control system |
| Design choice | The CCR’s number of steps: commonly 5 for high-intensity circuits, 3 for others |
Frequently Asked Questions
Q1What is CCR step selection?
Choosing which intensity step each constant current regulator runs at, so that its lights are bright enough to be seen in the current conditions without being so bright that they dazzle.
Q2What decides which step to use?
Mainly the background light (day, dusk or night) and the visibility (clear, haze, fog or low runway visual range), applied through the airport's own procedure for each lighting system. Pilot requests can also raise or lower a step.
Q3Why not run every circuit at the highest step?
At night or in clear conditions the top steps can dazzle pilots, hide the pattern in glare and shorten lamp life. The aim is just enough light to be seen clearly, which is why lower steps exist.
Q4Is the same step used for every lighting system?
Not necessarily. Approach, runway edge, centreline, touchdown zone and taxiway lights are on separate circuits with separate regulators, and the airport's procedure usually gives each system its own step for each condition.
Q5Who selects the step?
Usually air traffic control or the airfield operator, from the tower panel or the control and monitoring system. The step can also be set locally at the CCR, normally only for maintenance and testing.
Q6How do you confirm the step actually changed?
Check the step shown on the CCR display or control system, and where needed measure the output current with a calibrated true-RMS meter against the rated value for that step.
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