Definition
An FAA-published aeronautical chart used for IFR navigation below 18,000 feet MSL. It depicts the low-altitude airway system, including Victor airways, navigation aids (VORs, NDBs), intersections, minimum en route altitudes, controlled airspace boundaries, communication frequencies, and airports with instrument approach procedures.
Plain English
A flight chart pilots use when flying on instruments at lower altitudes. It shows the routes, radio navigation stations, airspace, and airports they need below 18,000 feet.
Context Anchor
You see this chart during instrument flight planning and while flying the en route part of an IFR flight, after departure and before the approach phase.
Derivation
"En route" comes from French, meaning "on the way." The chart is named for the phase of flight it supports — the part between departure and arrival, while you're on your way.
Why Pilots Care
Pilots use it to follow approved routes, identify navigation fixes, and maintain safe separation from terrain and obstacles when flying under instrument rules.
Intuition Check
Do not read “low altitude” as “near the ground.” Here it means the lower published instrument-route system, generally below 18,000 feet mean sea level. Do not read “en route” as including every detail of takeoff and landing. It mainly covers the between-airports portion of the flight.
Example Sentence 1
Before the IFR flight, the pilot pulled up the U.S. Low Altitude En route chart to check the airways and minimum en route altitudes along the route.
Example Sentence 2
During preflight planning, the instructor pointed out a closed airport symbol on the U.S. Low Altitude En route chart.