Definition
A propeller whose blade angle (pitch) can be adjusted in flight by the pilot, allowing the engine and propeller to operate efficiently across different phases of flight such as takeoff, climb, and cruise.
Plain English
A propeller where the pilot can change the angle of the blades while flying, so the engine works efficiently whether you need lots of pulling power for takeoff or smooth cruising at altitude.
Context Anchor
You will see this term in aircraft systems, performance, and engine operation discussions, especially when learning how to set propeller controls for takeoff, climb, and cruise.
Derivation
‘Pitch’ here refers to the angle of the propeller blades as they slice through the air, similar to the threads of a screw. ‘Controllable’ simply means the pilot can change it from the cockpit, rather than the angle being fixed at the factory.
Why Pilots Care
It improves thrust efficiency, reduces engine wear, and lowers fuel consumption by matching blade angle to airspeed and power setting.
Analogy
Think of it like the gears on a bicycle. A low gear (flat pitch) gives you strong acceleration from a stop; a high gear (coarse pitch) lets you cover ground efficiently once you're up to speed.
Intuition Check
Pitch here does not mean the airplane’s nose-up or nose-down attitude, and it does not mean musical sound. It means the angle of the propeller blades.
Example Sentence 1
Before takeoff, the pilot moved the propeller control fully forward to set the controllable-pitch propeller to a low blade angle for maximum thrust.
Example Sentence 2
Once level in cruise, the pilot increased propeller pitch to let the engine run at a lower RPM while maintaining speed.