Definition
In a multi-engine airplane with one engine inoperative, VXSE is the airspeed that produces the greatest gain in altitude per unit of horizontal distance traveled. It is published in the Airplane Flight Manual and is used when maximum altitude gain over the shortest ground distance is required, such as clearing an obstacle after an engine failure during or shortly after takeoff.
Plain English
The speed that gives you the steepest possible climb when one engine has quit on a twin. Flying at this speed gets you the most height in the shortest distance over the ground.
Context Anchor
Seen in multiengine airplane performance charts, emergency procedures, and discussions of climb performance after an engine failure.
Derivation
The 'V' stands for velocity (speed). 'X' is the standard FAA shorthand for best angle of climb. 'SE' means single engine — meaning one engine is operating, not two. So VXSE = velocity, best angle of climb, single engine.
Why Pilots Care
Provides maximum obstacle clearance during climb after an engine failure.
Intuition Check
VXSE is not the speed for the fastest climb over time. It is the speed for the steepest climb path over the ground with one engine not producing power.
Example Sentence 1
After the right engine failed on climbout, the pilot pitched for VXSE to clear the rising terrain ahead before accelerating to a cruise climb.
Example Sentence 2
The POH lists VXSE at 78 knots for this weight and altitude.