Definition
A ground reference maneuver in which the airplane flies a continuous series of opposite-direction half-circles of equal size on either side of a straight reference line on the ground, while maintaining a constant altitude. The pilot varies bank angle throughout each half-circle to compensate for wind drift, so that each half-circle traces an equal, symmetrical pattern over the ground.
Plain English
Flying a series of equal half-circles back and forth across a straight line on the ground, like a road, while keeping the same height. The pilot adjusts how steeply the airplane is banked during each turn to keep the half-circles the same size despite the wind.
Context Anchor
Seen in ground-reference maneuver training, usually practiced over a straight road, fence line, or other clear line on the ground.
Derivation
Named for the shape the flight path traces over the ground: each pair of opposite half-circles, joined at the reference line, looks like the letter S.
Why Pilots Care
Builds the skill of maintaining a precise ground track in wind, directly improving traffic pattern accuracy and crosswind landing safety.
Intuition Check
An S-turn is not just any loose, wavy turn. In this training maneuver, the shape is planned around a straight ground line, and each half-circle is controlled for wind.
Example Sentence 1
The instructor demonstrated S-turns across a country road, rolling into a steeper bank when the airplane was being pushed downwind.
Example Sentence 2
On the downwind side of the S-turn the pilot used a steeper bank to keep the radius constant against the wind.