Here are the top 20 most used. What information do you need? Happy to help if I am able
Frequency-------- Airports Using it
122.900 ---------------- 1947
122.800---------------- 1646
122.700---------------- 401
123.000---------------- 388
121.9---------------- 215
123.050---------------- 132
121.7---------------- 121
121.8 ---------------- 90
118.325----------------71
118.375---------------- 59
123.075---------------- 58
119.025---------------- 58
123.600---------------- 56
118.525---------------- 55
122.725--------------- 54
119.275---------------- 51
119.925---------------- 47
121.6---------------- 46
122.975---------------- 44
118.175---------------- 37
Just a small nitpick. "Used" as in allocated and coordinated.
Most towered airports have multiple voice frequencies coordinated to them, all the usual stuff, Tower, Ground, Clearance, and often two or three backup frequencies, some published, some not.
I'd ask for sure about the unpublished ones, and whether or not they're in the public database for public consumption, but the friend who could answer that might only be able to tell me if he kills me.
And then there's the military airports...
Recently a local DPE posted a photo of the frequency panel at the home airport tower. It was just in a collage of other photos he took.
I commented that a couple of those frequencies aren't published on charts, for reasons of use during interference and other reasons, but that I didn't think they were truly any Big Secret(TM) and I used to feed one of them that I'd learned of when I did the LiveATC feed of KAPA. I had a hell of a time finding the thing, but I knew there was some other Tower traffic on it, and I finally caught it one day, but didn't put it in the LiveATC node description frequencies.
I noticed he took the photo down. Whether out of caution, or he realized they really are a Big Secret(TM) or he asked the tower folks about it, I don't know. I'm guessing just out of caution.
Having now helped a friend apply for his air show frequencies a couple of years in a row now, because the FCC system for new applications requires an insanely old version of Java... there's also that stuff... air shows and other special events get coordinated frequencies assigned to them by FAA all the time, and the FAA doc authorizing the temporary radio station is attached to the FCC application as part of that absolutely horrid software and process. As well as the military and civilian flight teams having their own coordinated frequencies via FAA and FCC...
And then there's AIRINC stuff...
So if you're looking for stuff to put in a receiver, often you're just going to have to resort to full band scanning from time to time to catch things. Modern scanners are incredibly fast at it, and SDRs with a waterfall display also come in quite handy.
Most folks will just program up the published stuff and call it a day, though. It's the path of least resistance. But the frequencies in the database often are the dead quiet published backup frequencies.
Since you have it downloaded
@SixPapaCharlie, peek at your local airports on the chart and also in the DB and see if there's more frequencies in the database than on the chart. I bet there are.
You'd likely be correct to do a JOIN on those two data sets to find the "busy" frequencies, if they're different.
And there's your radio nerd post about frequency coordination. Sorry. It's a curse.
