Definition
Flight instruction received during a cross-country flight to a destination more than 50 nautical miles from the departure airport, used by a recreational pilot to gain authorization to fly beyond the 50 NM limit that otherwise applies to their certificate.
Plain English
It is training a recreational pilot does with an instructor while actually flying somewhere far away, so the pilot can later be allowed to make those longer trips on their own.
Context Anchor
Seen in recreational pilot privileges and limitations, especially when discussing flights beyond the normal local-area limits.
Derivation
En route' comes from French, meaning 'on the way.' So en route training is training that happens while on the way to a destination, rather than in the local practice area.
Why Pilots Care
A recreational pilot is normally restricted to flying within 50 NM of their departure airport. Completing en route training and getting the proper logbook endorsement is what unlocks the ability to fly cross-country beyond that limit.
Intuition Check
Do not read en route training as any training that happens while airborne. Here it means training specifically focused on flying and managing the route between places.
Example Sentence 1
Before her trip to visit family two states away, the recreational pilot completed en route training with her instructor and received the required endorsement.
Example Sentence 2
Logging en route training during the return leg helped the student meet the recreational pilot cross-country requirement without extra flights.