Pilot Controlled Lighting (PCL) or Aircraft Radio Control of Aerodrome Lighting (ARCAL) is a technical system by which aircraft pilots can control the lighting of an airport or airfield's runways and taxiways via radio. PCL systems are most common at uncontrolled or little used airfields where it is not economical to light the runways all night every night nor to maintain staff to turn the runway lighting on and off as needed. PCL enables pilots to control the lighting only when they require it, thereby saving electricity and reducing light pollution.
If the airfield supports PCL, the pilot sets their radio to the ARCAL frequency for the airport (which is often, but not always, the same as the UNICOM /CTAF frequency (e.g. Smiths Falls-Montague Airport hosts separate Unicom and ARCAL frequencies). The systems are then typically operated by performing a series of clicks with the radio microphone talk button.
PCL systems most often have three settings:
- Low intensity: Three clicks within five seconds
- Medium intensity: Five clicks within five seconds
- High intensity: Seven clicks within five seconds
When the lighting system is activated, a 15 minute countdown starts, after which, the lights turn off. While the lights are still active, whenever a lighting command is issued, whether it changes the lighting intensity or not, the 15 minute countdown is reset. At some airfields, special lights may blink for ten seconds to warn pilots before the lights shut off.
When using PCL, it is very highly recommened that aircraft on final approach to the airfield issue a fresh lighting command even if the lights are already on (especially if the lights were activated by another aircraft). This is so that the lighting does not go off by surprise at a critical moment (such as when crossing the runway threshold).
