Definition
A specific low-altitude Federal airway in the United States, identified by the color Green and the number 13. Colored airways (Green, Red, Amber, Blue) are low-altitude routes defined by ground-based navigation aids, primarily used in Alaska and over coastal waters where Victor (VOR-based) airways are not practical. Green airways run generally east-west.
Plain English
A named low-altitude flight path in the sky called Green 13. It is one of the older 'colored' airways that pilots can fly along, mostly used in Alaska and over water. Green airways go roughly east-west.
Context Anchor
Seen on IFR en route charts, route descriptions, and instrument clearances involving the colored airway system, especially in Alaska.
Derivation
The colored airway system dates to the 1920s and 1930s, when U.S. airways were assigned colors based on their direction. Green and Red airways run east-west; Amber and Blue run north-south. The naming has stuck even though most of the lower 48 has since moved to Victor airways based on VORs.
Why Pilots Care
It provides an approved route for navigation, traffic separation, and safe instrument flight in areas where Victor airways are not used.
Analogy
Think of it like a named highway. “Green 13” is not just a color and a number; it is the route name, like “Highway 13,” with a specific path shown on the map.
Intuition Check
Green does not mean the route is automatically safe, open, or preferred. Here, Green is part of the airway’s official name.
Example Sentence 1
Cleared direct to the Bethel VOR, then via Green 13 to Anchorage.
Example Sentence 2
ATC cleared the aircraft to join Green 13 at the next intersection.