Definition
Aeronautical charts used for IFR navigation at and above 18,000 feet MSL. They depict jet routes, high-altitude airways, navigation aids, intersections, controlled airspace, and other information needed for flight in the high-altitude structure.
Plain English
The IFR charts pilots use when flying high — from 18,000 feet up to 45,000 feet. They show the routes, navigation aids, and reporting points used at those altitudes.
Context Anchor
Seen during IFR flight planning and in-flight navigation for routes flown in the higher-altitude en route system, especially above 18,000 feet.
Derivation
En route comes from French and means “on the way.” In aviation, the en route part of a flight is the portion after leaving the departure area and before entering the arrival area. That helps explain why these charts focus on the middle, traveling portion of an instrument flight.
Why Pilots Care
They ensure pilots have the correct routing and altitude information to maintain separation and navigate safely in high-altitude airspace.
Intuition Check
Do not read “high-altitude” as just any flight that feels high. Here it refers to a specific IFR chart series for the upper-altitude route system, generally beginning at 18,000 feet above mean sea level.
Example Sentence 1
Before departing on the jet route portion of the flight, the crew pulled up the high-altitude en route chart to review the J-route and crossing fixes.
Example Sentence 2
On the high-altitude en route chart, the minimum en route altitude for that segment was clearly marked.