Definition
A propeller design in which the blade angle (pitch) can be changed only on the ground, with the engine stopped, by loosening the blade clamps in the hub and rotating each blade to the desired setting before retightening. Once set, the pitch remains fixed throughout flight and cannot be altered by the pilot.
Plain English
A propeller whose blade angle can be adjusted by a mechanic on the ground, but stays locked in place once the airplane is flying.
Context Anchor
Seen when identifying propeller types during an exterior inspection or when reading aircraft information about how the propeller is set up.
Derivation
Pitch' here refers to the angle of the propeller blade, borrowed from the idea of how far a screw advances per turn. 'Ground adjustable' simply tells you when the adjustment can be made — on the ground, not in flight.
Why Pilots Care
Lets the pilot choose an angle suited to the planned flight, but removes any ability to optimize for climb versus cruise once airborne.
Intuition Check
Do not read ground adjustable as a cockpit control the pilot uses while sitting on the ground. It means the propeller blade angle is physically set on the ground and then remains fixed during the flight.
Example Sentence 1
Before the cross-country flight, the owner had the ground adjustable pitch propeller set to a steeper angle to favor cruise performance.
Example Sentence 2
Because the propeller had ground adjustable pitch, the pilot could not fine-tune blade angle after takeoff to improve cruise speed.