Definition
Published IFR routes that exist in Class A airspace, from 18,000 feet MSL up to and including FL 450. In the United States these are called jet routes and are designated with the letter J followed by a number (for example, J80). They are defined by VOR navigation aids or, increasingly, by RNAV waypoints, and they form the upper-level structure of the en route airway system.
Plain English
These are the highway-style routes airplanes follow when flying high up — generally at the levels used by airliners and turbine aircraft. In the U.S. they have names that start with the letter J.
Context Anchor
You see this term when planning or reading instrument routes for flights at 18,000 feet and above, especially on high-altitude en route charts.
Why Pilots Care
These routes provide the structure for safe, efficient high-speed travel, direct ATC routing, and access to flight levels where aircraft performance is optimal.
Analogy
Think of them like major highways for aircraft flying high overhead. They are not physical roads, but they give pilots and controllers a shared route to follow.
Intuition Check
High altitude airways do not mean any route that happens to be high. Here, the phrase refers to specific published instrument routes in the high-altitude en route system.
Example Sentence 1
The crew filed an IFR flight plan along J80 at FL350, using the high altitude airways for the cross-country leg.
Example Sentence 2
After departure the crew climbed to join the high altitude airways and received a direct clearance to the next fix.