Definition
The propeller blade angle setting in which the blades are rotated so their flat (chord) side is nearly perpendicular to the direction of flight, producing minimum thrust and minimum drag from the propeller. It is the low-pitch, high-rpm end of the blade-angle range, used for ground operations, low airspeeds, and full-power conditions where the engine needs to turn freely.
Plain English
The blades are turned so they bite the air very lightly, like a knife edge slicing through it. The engine spins easily and the propeller pulls only a small amount of air through.
Context Anchor
Seen in discussions of feathering propellers, especially when describing how a propeller moves between feathered and normal operating positions.
Derivation
"Flat" here means the blade face is presented flat to the oncoming air, with little angle. The term describes what the blade looks like from the side: nearly flat to the airflow rather than turned edge-on.
Why Pilots Care
Knowing the flat pitch stop helps pilots understand why the propeller control must be set correctly before engine start or takeoff and why feathering systems bypass this position entirely in an emergency.
Analogy
It is like turning a paddle in the water. Held flatter, it slips through with less bite; turned more across the water, it takes a bigger bite.
Intuition Check
Flat does not mean the blade has no angle at all. Here it means a lower blade angle compared with high pitch or feathered position. Pitch here means propeller blade angle, not the airplane’s nose-up or nose-down attitude.
Example Sentence 1
On takeoff roll, the propeller is in the flat pitch position, allowing the engine to reach maximum rpm.
Example Sentence 2
During a go-around the propeller governor returned the blades toward the flat pitch position to restore full RPM quickly.