Definition
The airspeed that produces the greatest gain in altitude per unit of horizontal distance traveled. At VX, the airplane climbs at the steepest possible angle relative to the ground.
Plain English
The speed that gets you the most height in the shortest distance forward. You climb steeply, not quickly.
Context Anchor
You will see VX in takeoff, obstacle-clearance, and performance discussions, especially when deciding what climb speed to use after liftoff.
Derivation
The 'V' in VX stands for velocity (speed). The 'X' is simply the label aviation uses to mark this particular climb speed, distinguishing it from VY (best rate of climb). Knowing V means velocity helps decode the whole family of V-speeds.
Why Pilots Care
It enables the aircraft to clear nearby obstacles safely after liftoff.
Analogy
Think of VX like choosing the steepest safe path up a hill when you have very little space before a fence. It is not the fastest way to gain height over time; it is the best way to gain height over distance.
Intuition Check
Do not assume VX means pulling the nose as high as possible. VX is a specific airspeed that gives the steepest climb path over the ground.
Example Sentence 1
After liftoff, the pilot held VX until the airplane cleared the trees at the far end of the runway, then accelerated to VY.
Example Sentence 2
After liftoff the student held VX until reaching a safe altitude above the terrain.