So if your one of those guys that scans McCarran freqs like me, there's a freq used for Menzies Fuelers (The old ASIG) 460.6500 pl 179.9 When it's raining like this time of year you may hear occasional DTMF on the freq. That's the lightning warning system, it turns on remote lights kinda like the old k-mart blue lights. Basically giving a visual warning to the fuelers and rampers that lightning has been detected within three miles and to stop fueling and seek shelter from approaching storm. There are several lights on pushback tugs. I downloaded the radio that turns it on the DTMF is 6573. If you hear any DTMF on that freq you can bet lightning in the area. Not that you really need a signal to tell it's raining out.