Definition
The airspeed used during the climb segment after the airplane has reached a safe altitude and is climbing toward cruise. It is typically faster than the takeoff or initial climb speed and is chosen to give a good balance of forward progress, engine cooling, and a reasonable rate of climb.
Plain English
The speed you settle into once you're done with the takeoff climb and are climbing on your way to cruise altitude. It's faster than the speed used right after takeoff because the priority shifts from clearing obstacles to making good time and keeping the engine cool.
Context Anchor
Seen in takeoff and climb procedures, especially after liftoff when the airplane is transitioning from the first climb after takeoff into the normal climb away from the airport.
Derivation
En route' comes from French, meaning 'on the way.' It refers to the portion of flight between the departure airport and the destination — the cruising part of the trip. So 'en route climb speed' is simply the speed used while climbing on the way to where you're going.
Why Pilots Care
Selecting the proper en route climb speed improves forward progress and fuel efficiency while still gaining altitude, directly affecting trip time and engine cooling.
Grounding Statement
Picture clearing the nearby trees, then easing the nose slightly lower so the airplane keeps climbing but also gains the normal speed for leaving the airport area.
Intuition Check
Do not assume en route climb speed means any speed used during a climb. Here it means the recommended normal climb speed after the initial takeoff or obstacle-clearance climb, and it is not automatically the steepest-climb or fastest-climb speed.
Example Sentence 1
Once clear of obstacles and established in the climb, the pilot accelerated to the en route climb speed published in the POH.
Example Sentence 2
The POH lists a lower en route climb speed for high-density-altitude conditions to maintain adequate engine cooling.