Pilot-Controlled Lighting Tips, Reporting Needs

Most folks who are not involved with aviation wouldn't know that a radio pulse sequence is used to "key-up" the runway lighting system, as the pilot is on approach. The average citizen may think that the pilot "calls" down with their radio to somebody at the tower or A/D building and instructs them to "turn on the lights." Of course, in the aero world we know this is not the case because most airports don't have staff present around the clock.

The Pilot Controlled Lighting system puts the power into the pilot's hands – to control the airport lighting system on the ground, from the aircraft.

The radio receiver that controls the PCL system at each airport is constantly monitoring the radio traffic on the local airport radio frequency and is watching for clicks. A click is made by simply tapping the microphone's transmit button on an air-band radio transmitter, and then releasing it right away. If you tap three times within a five second duration, the lights should turn on at low intensity. Five clicks activates medium airfield light intensity, and seven clicks brings up high intensity. If you are flying at night and need to decrease the intensity, simply click the appropriate number of times for the desired intensity and the lighting system will adjust. Do not click too fast though! The radio controller needs a slight window between clicks to interpret the input as a pulse.

Have you flown into one of Minnesota's airports and had very inconsistent results when keying up the airport lighting systems? Or, have you tried to switch the intensity of the lights, and it seems to take more clicks of the radio than it should? This is a problem that should be addressed as soon as possible, to restore the system to its intended parameters. We are asking pilots to take notice of any abnormalities and pass them along to the airport manager.

When MnDOT's NavAids team performs maintenance checks of the PCL radio receiver, we can use our handheld equipment to test the functionality of the system. But, the best testing procedure is done from the air at a longer range. For that reason, it's best if pilots report any potential problems directly to the airport's manager. Many of our Minnesota airport managers are experienced and able to correct problems in-house.

Airport managers who run into tricky outage scenarios are welcome to reach out to MnDOT's NavAids group for additional troubleshooting assistance.

Here's a list of a few of the issues that may cause outages to the PCL system, and possible solutions airports might take to get everything back up and running.

Pilot-controlled lighting systems are very dependable most of the time, but every component has its own inherent service life. The PCL radio receiver can start to lose its range as components wear out. As this happens, it can drop the system out of its designed tolerances and become unreliable.

Possible solution: A precision signal generator is brought out to the site. The signal generator plugs directly into the radio receiver and can

feed precise signal feeds to determine if the radio is properly adjusted to tolerances.

The electrical relays inside the radio assembly can get weak and might not engage firmly at the connection points. The relay points can accumulate some corrosion or charring as well. Possible solution: Some brands of radio receiver allow for the replacement of components as they begin to wear out. This isn't always an option, and sometimes the whole receiver itself must be changed.

The radio transmitter itself can create issues. This may be the radio transmitter in an aircraft, vehicle, or handheld. Possible solution: Pilots must verify that the aircraft's radio is putting out the proper signal strength and characteristics.

One simple way to do this, is to run a test with the suspect radio, alongside a similar radio that is known to be working well. Do they act the same? Give the same kind of range?

It's easy to only consider the problem to be with the equipment at the airport. Sometimes the signal itself can be disturbed by an outside factor. A local AM/FM radio station could unknowingly create interference because of a problem with their own equipment. Possible solution: The airport along with NavAids would look to isolate what's causing the disturbance and contact the appropriate party.

A large obstruction nearby might affect the radio's efficacy. Perhaps the construction of a big factory, bridge or overpass is causing interference.

Possible solution: Since it's likely not possible to remove the building on an issue like this, a radio engineer gets involved to determine corrective action.

When pilot-controlled radio systems are not working properly, a pilot has fewer resources available to assist with carrying out safe operations at the airport. Realistically, there will always be outages from time to time as equipment ages. Our MnDOT Aeronautics NavAids group strives to accurately report when the systems are down, by using the NOTAM system.

We want all pilots to be aware of any systems that are acting up or taken offline for repairs.

What can you do to help ensure PCL systems are operating as they should, and keeping pilots and their passengers safe? We are calling on you folks who travel through the skies to help us. Activate (test) those airfield lights. If you notice an issue, bring it to your airport manager's attention. The next pilot that is coming in behind you might have lower visibility and may be counting on those lights.