Definition
The phase of flight between the end of departure (climb-out and initial routing) and the beginning of arrival (descent and approach), during which the aircraft is flying along its planned course toward the destination.
Plain English
The middle part of the flight — after takeoff and climb, before descent and approach — when the aircraft is travelling from one place to another.
Context Anchor
Seen in FAA abbreviation lists, flight planning, weather briefings, and NOTAMs, which are official notices about information important to flight.
Derivation
From the French 'en route,' meaning 'on the way' or 'on the road.' Aviation borrowed it directly to describe the part of a flight spent travelling between origin and destination.
Why Pilots Care
En route conditions directly affect fuel planning, weather decisions, and navigation for the longest portion of most flights.
Intuition Check
Do not read en route as just a casual phrase meaning “somewhere along the trip.” In aviation use, it points to the between-departure-and-arrival part of the flight or operation.
Example Sentence 1
Once established at cruise altitude, the pilot switched to the en route chart to follow the planned course.
Example Sentence 2
ENRT forecasts showed icing conditions along the planned route.