Tracon Frequencies


Mar 12, 2017
Why so many departure frequencies? Specifically milwaukee area. I know there are many sectors but why does the class D airport have 1 departure freq and 5 miles away in class E it's different.....Then 3 miles farther it's different. Being a little sarcastic but on my map program (foreflight) it doesn't make sense that there would be 3 different departure frequencies all within a small area. If i want flight following it makes it difficult to know what to use especially when the sectional gives a 4th and different freq.....of course the sectional just gives north/south/east/west.

Also chicago overlies on top of that or surrounds the mke area it doesn't control. Anyone have mke and chicago sector map to show the boundaries ?

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Trusted Member
Aug 19, 2011
The C90/MKE approach control boundary is mostly the IL/WI state line. There are cutouts for KUGN and KENW and a little C90 extension up higher. These are invisible to the pilot though. For VFR, let's just stick with whatever the sectional says. Local FBOs often have little tidbits about this stuff too in their planning rooms.

For MKE Approach, the frequency boxes indicating 126.5 or 118.0 kind of presume you're inbound to KMKE proper or overflying the area. So those are probably the most normal/commonly used frequencies, likely a North and South Approach/Departure Control. I don't pretend to know MKE airspace well, but this is generally the case with those text boxes. You're always OK to call approach on those frequencies (try to use the one nearest your location), and if they want you on a different one, they'll tell you.

KUES and KMWC approach plates list 125.35 as their approach control frequency. Most likely, MKE Approach has a separate satellite sector for this area. Likewise KENW and KRAC have 135.87 available. This leads me to believe they have North and South Satellite positions alike. They're probably lower level sectors than the above-two frequencies, and away from KMKE a bit.

KOSH has 127.0, KSBM has 127.37... and the Chart Supplement (formerly know as A/FD) also shows 127.85. So that says to me there are at least 7 sectors at MKE Approach, barring one sector owning multiple frequencies.

If you're departing a Class D, you can just ask the tower which departure frequency to use, but I'd say it's most likely going to be the frequency listed on the approach plate. Most of the time those towers issue a standard departure frequency (the overlying formal satellite sector) to their IFR departures by LOA. This is likely just fine for VFR use as well.

If you're departing an E/G airport, or otherwise don't want to think hard, use the explicitly emphasized and highlighted frequency right there on the chart closest to wherever you are. If they want you elsewhere, they'll put you on someone else. Not like you need to perfectly know the right frequency to use when you're VFR. Long as you follow your airspace comms rules prior to entry, you'll be fine.

Local knowledge becomes a thing too. If you know that every time you call up 126.5 after departing 02C airport and they always immediately stick you on 125.35, you might be able to save both your and the controller's time in the future by skipping the 126.5 call. Or if you're southbound out of KENW, MKE Approach may or may not want you to call them and just give you over to Chicago on 120.55. You'll learn best by just using the system.
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Epic Member
Jan 31, 2009
MKE approach splits in an East and west configuration as well as north/south for departures. How they split is based on their current airport configuration. We even use different frequencies based on what arrival configuration ORD is on (east vs west flow), there's additionally splits based on altitude too. In general 125.35 is their catch all unless you're actually going to land at MKE. The area to the north with osh and sbm is the Ripon sector of mke which also splits in an East/ West configuration.