Like all ground reference maneuvers, S-turns are practiced to cement the fundamentals of aircraft control. The goal is to develop aircraft control coordination by flying the aircraft along a precise ground track at a constant altitude. Although rarely perfect on the first try, the maneuver is actually quite easy as long as you know what to look for.
In an S-turn, the goal is to fly two equally sized half-circles. In a no-wind condition, the maneuver is theoretically pointless. You could arbitrarily pick a bank angle and turn 180º left, then do it again to the right. But that defeats the point.
We’re supposed to be learning about wind drift, division of attention, and all sorts of pilot-y things like that. So it shouldn’t come as much of a surprise that your flight instructor will pick only the windiest days to practice S-turns.
Because of wind drift, we have to constantly change bank angle throughout the maneuver. This is where it gets tricky. Let’s break it down into seven simple steps:
Step 1: Choose a road or other straight line that is perpendicular to the wind as your primary ground reference. Maneuver to cross the road at 600′-1000′ AGL on the downwind.
Step 2: Roll into a steep (40º-45°) left turn as you cross the road. As you turn crosswind, you will lose groundspeed due to the decreasing tailwind component. Compensate by decreasing bank angle as needed.
Step 3: Continue the turn and gradually decrease bank angle. This will be the shallowest bank of the first 180º turn.
Step 4: Roll out to wings level while crossing the road. Enter a shallow bank right turn and gradually increase bank angle.
Step 5: Continue the turn while slowly increasing bank angle to 40°-45°.
Step 6: Cross the perpendicular to the road on the maneuver’s entry heading with wings level.
Step 7: Retrim for level flight as needed and accomplish any necessary post maneuver checklists.
Although the seven steps sound pretty complicated, relax: the S-turn is a snap if you know one little secret: pick multiple ground references. As you approach the maneuver entry point, scope out the surrounding landscape and “trace” your intended flight path.
Visualize the desired ground track out the window and pick out a few landmarks as extra references. Fly to the swimming pool here, go over the red barn there, pass between the two trees, then wings level over the road. At this point, it’s as easy as playing Connect the Dots with an airplane!
This is a required maneuver for the Private Pilot checkride. The Private Pilot Practical Test Standards (PTS) require an altitude of +/- 100′ and airspeed +/- 10 knots along with adequate wind-drift correction to maintain constant radius turns.