Attention pilots transiting Chicago TRACON (C90) airspace—especially those heading to or departing from EAA AirVenture in Oshkosh (KOSH):
The departure frequency 125.0 MHz is currently unusable.
Per the updated NOTAM, traffic should contact ATC on 128.57 MHz when operating in the affected sector of Chicago TRACON airspace.
This change is critical for ensuring safe and efficient communications during one of the busiest aviation weeks of the year. Please update your flight plans, avionics, and briefings accordingly.
You can review the full notice here:
https://www.faasafety.gov/files/notices/2025/Jul/OSH25-Chicago.pdf
Key Takeaways:
- Old frequency (125.0 MHz) is unusable.
- New frequency (128.57 MHz).
- Applies to departures/arrivals in the affected area during EAA AirVenture 2025
- Effective July 22–29, 2025
Fly safe, stay alert, and enjoy your trip to Oshkosh!
The iFlightPlanner Crew
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