How many of these symbols have you seen?
1) Stand-Alone AWOS/ASOS Weather Stations
Not connected to an airport, you'll find stand-alone AWOS and ASOS stations charted on enroute charts. They're common in places like the Colorado Rockies, where a few stand-alone weather stations have been installed to help you analyze localized mountain weather patterns.
2) LF/MF Airways (Alaska Only + 1 In North Carolina)
LF/MF airways (airways based on LF/MF NAVAIDs) are sometimes referred to as colored airways because they are identified by color name and number (e.g., Amber One, charted as A1). Green and red airways are plotted east and west, and amber and blue airways are plotted north and south. Regardless of their color identifier, LF/MF airways are depicted in brown.
They're most commonly found in Alaska, but one still remains in the lower 48. It's called G13 and navigated off of the Manteo (MQI) NDB, located along North Carolina's coastline.
3) Helicopter RNAV Routes (TK Routes)
Two helicopter RNAV routes (TK-routes) exist in the northeast corridor between the Washington, DC, and New York City metropolitan areas. The TK-routes are for use by helicopters having IFR-approved Global Positioning System (GPS)/Global Navigation Satellite System (GNSS) equipment.
4) Cold Weather Corrections
In cold regions of the country, instrument approaches require cold weather corrections. It's your responsibility to make sure you know how to correct the altitudes, and which segments of the approach need to be corrected.
5) NDB-DME Stations
Ambler is an NDB-DME with both and NDB frequency of 403, as well as a DME channel of 108, both of which are listed on the enroute chart.
6) Crossing Altitudes By Compass Direction
The MCA (Minimum Crossing Altitude) is 8,400 MSL when flying south, as you can see on the chart.
7) MEA Gap
If you're flying along this route at the MEA, you could lose ground-based navigational coverage along this segment of V134.
What other rare symbols IFR symbols did we miss? Tell us in the comments below.
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