You’re scanning blackness below, looking for the nontowered airport, when you spot the rotating beacon.

When it receives a series of electrical pulses within a five-second period, a decoder energizes one, two, or three relays to activate pilot-controlled lighting. The first pulse from a microphone click starts the five-second window, and the relays are de-energized after 15 minutes.

Q: What does it mean if, while I’m approaching to land, all the airport lights suddenly go dark, then blink back on again? A: That’s a warning sign the 15-minute activation period is about to expire. Click seven times within five seconds to restart the 15-minute timer. Q: Is the PCL radio frequency listed on the VFR sectional chart? A: No. That information is only found in the chart supplement (formerly the airport/facility directory) and instrument approach procedures.

Already tuned to the airport’s unicom frequency, you press the radio transmit button seven times in quick succession, and suddenly the entire airfield lights up like a Christmas tree. White runway edge lights, blue taxiway lights, red and white visual approach slope indicators, strobe-like runway end identifier lights, and even the mesmerizing “rabbit” from the approach lighting system. The lights stay on for 15 minutes, plenty of time to land and taxi to the ramp. And if you want more time, repeat the series of button clicks to reset the timer.

Pilot-Controlled Lighting (PCL) systems are common at nontowered airports, and towered airports in the wee hours after controllers have gone home. PCLs almost always are activated on the common traffic advisory frequency and details can be found in the chart supplement (formerly known as the airport/facility directory).

There are several different kinds of PCL systems, but they all share similarities. Clicking seven times within five seconds when you’re five miles or less from the airport activates them, and the lights stay on for 15 minutes following activation. Some systems allow pilots to adjust the lighting intensity: three clicks for low, five clicks for medium, and seven clicks for high, once it’s been activated.

PCLs are popular because they save money. Rural airports don’t have to leave the lights on all the time at night and during periods of low visibility, when few—if any—airplanes are taking off or landing.