Wind Wings Level Shallowest Bank Moderate Bank Steepest Bank Moderate Bank Shallowest Bank Steepest Bank 2 1 3 4 5 6 Entry Wings Level to Start Maneuver Figure 9-6.  S-Turn. The objectives of S-turns across a road are to develop  the ability to compensate for drift during turns, orient the  flightpath with ground references, follow an assigned ground  track, arrive at specified points on assigned headings, and  divide the pilot’s attention. The maneuver consists of crossing  the road at a 90° angle and immediately beginning a series  of 180° turns of uniform radius in opposite directions,  re-crossing the road at a 90° angle just as each 180° turn  is completed. The maneuver can be started with either a  left hand turn or a right hand turn to go in either direction.  Figure 9-6  starts the turn in a left hand turn as an example. The road should be approached from the upwind side at the  selected altitude on a downwind heading. When directly  over the road, the first turn should be started immediately.  [Figure 9-6, position 1  and  Figure 9-7]  With the aircraft  headed downwind, the groundspeed is greatest and the rate  of departure from the road is rapid; the roll into the steep  bank must be fairly rapid to attain the proper wind correction  angle.  [Figure 9-6, position 2]  This prevents the aircraft from  flying too far from the road and from establishing a ground  track of excessive radius. Accomplishing a constant radius ground track requires  a changing roll rate and angle of bank to establish the  wind correction angle. Both increase or decrease as the  groundspeed increases or decreases. The bank must be steepest when beginning the turn on the  downwind side of the road and must be shallowed gradually  as the turn progresses from a downwind heading to an upwind  heading. On the upwind side, the turn should be started with  a relatively shallow bank and then gradually steepened as  the aircraft turns from an upwind heading to a downwind  heading. In this maneuver, the aircraft should be rolled from  one bank directly into the opposite just as the 90° reference  line on the ground is crossed. Before starting the maneuver, a straight ground reference  line or road that lies 90° to the direction of the wind  should be selected, then the area checked to ensure that no  obstructions or other aircraft are in the immediate vicinity.  During the latter portion of the first 90° turn, when the  aircraft’s heading is changing from a downwind heading  to a crosswind heading, the groundspeed becomes  less and the rate of departure from the road decreases.  Reference Line Figure 9-7. Pilot’s view of crossing a reference line (road) at 90 ° wings level starting the S-turn maneuver. 9-8