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slower and shallower. These same techniques apply while
fl ying in airport traffi c patterns.
Common errors in the performance of rectangular courses
are:
• Failure to adequately clear the area.
• Failure to establish proper altitude prior to entry
(typically entering the maneuver while descending).
• Failure to establish appropriate wind correction angle,
resulting in drift.
• Gaining or losing altitude.
• Poor coordination (typically gaining or losing airspeed
during the turns).
• Abrupt control usage.
• Inability to divide attention adequately between
aircraft control and maintaining ground track.
• Improper timing in beginning and recovering from
turns.
• Inadequate visual lookout for other aircraft.
S-Turns Across a Road
An S-turn across a road is a practice maneuver in which the
aircraft’s ground track describes semicircles of equal radii on
each side of a selected straight line on the ground. Reference
Figure 9-6 throughout this S-turn across the road section. The
straight line may be a road, fence, railroad, or section line
that lies perpendicular to the wind and should be of suffi cient
length for making a series of turns. A constant altitude should
be maintained throughout the maneuver.
S-turns across a road present one of the most elementary
problems in the practical application of the turn and in the
correction for wind drift in turns. While the application of this
maneuver is considerably less advanced in some respects than
the rectangular course, it is taught after the student has been
introduced to that maneuver in order that the student may
have a knowledge of the correction for wind drift in straight
fl ight along a reference line before the student attempts to
correct for drift by playing a turn.
9-8
Reference Line
Figure 9-7. Pilot’s view of crossing a reference line (road) at 90°
wings level starting the S-turn maneuver.
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
fl ightpath with ground references, follow an assigned ground
track, arrive at specifi ed 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.
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.
The road should be approached from the upwind side at the
selected altitude on a downwind heading. When directly
over the road, the fi rst 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
fl ying too far from the road and from establishing a ground
track of excessive radius.
During the latter portion of the fi rst 90° turn, when the
aircraft’s heading is changing from a downwind heading
to a crosswind heading, the groundspeed becomes
　
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