Definition
A system of low-frequency/medium-frequency federal airways established between non-directional beacons (NDBs), identified by a color and a number rather than by a Victor route designator. The four colors used are green and red for east-west routes, and amber and blue for north-south routes. Colored airways are still depicted on IFR en route low altitude charts in a few areas, primarily coastal Alaska, where they remain in use.
Plain English
Older airways that connect NDB ground stations and are named by a color and number, like Green 2 or Blue 14. They mostly survive in parts of Alaska where NDBs are still the main navigation aids.
Context Anchor
Seen on IFR En Route Low Altitude Charts when reviewing published routes, especially in Alaska.
Derivation
Called "colored" because each route is shown and named with a color: green and amber, blue and red. The naming convention dates from the earliest U.S. airway system, before VORs and the Victor airway network replaced most low-frequency routes in the lower 48 states.
Why Pilots Care
If you fly IFR in Alaska or review charts that include colored airways, you need to recognize them as legitimate published routes you can file and fly, served by NDBs rather than VORs. Treating them as outdated or ignoring them can lead to filing errors or missed routing options.
Intuition Check
“Colored” does not mean the airway is simply drawn in a bright color on the chart. Here, the color is part of the official route name, such as Amber 1 or Blue 2.
Example Sentence 1
Flying IFR along the Alaskan coast, the pilot was cleared via Amber 1 between two NDBs.
Example Sentence 2
Reviewing the low altitude chart showed several colored airways available in the remote area.