Definition
The horizontal distance from the center of an airplane's turn to its flight path, measured perpendicular to the direction of travel. Turning radius increases with the square of true airspeed and decreases as the angle of bank increases.
Plain English
How wide a circle the airplane carves through the air when it turns. A tight turn has a small radius; a wide, sweeping turn has a large radius.
Context Anchor
Seen when practicing steep spirals and other ground-reference maneuvers, especially when trying to stay a consistent distance from a selected point on the ground.
Derivation
Radius comes from Latin and originally meant a spoke of a wheel or a ray from a center point. That helps here because turning radius is the distance from the center of the turn out to the airplane’s path, like the distance from the hub of a wheel to its rim.
Why Pilots Care
A consistent turning radius keeps the spiral centered over the chosen point and produces predictable altitude loss each turn.
Intuition Check
Turning radius is not just about how much the airplane’s nose is turning. It is the actual size of the curved path the airplane makes, especially over the ground in this maneuver.
Example Sentence 1
During the steep spiral, the pilot adjusted bank angle to keep a constant turning radius around the reference point on the ground.
Example Sentence 2
A wider turning radius gave more time to clear the area for traffic during the spiral descent.