X.B. S-Turns. References: FAA-H The student should develop knowledge of the elements related to S-turns as necessary in the Private Pilot PTS.

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1 References: FAA-H Objectives Key Elements Elements Schedule Equipment IP s Actions SP s Actions Completion Standards The student should develop knowledge of the elements related to S-turns as necessary in the Private Pilot PTS. 1. Wind Correction 2. Coordination 3. Emergency Landing Area 1. Selecting a Suitable Altitude 2. Selecting a Suitable Reference Line 3. The Basics 4. Prior to Entry 5. The Maneuver 6. Coordination 1. Discuss Objectives 2. Review material 3. Development 4. Conclusion 1. White board and markers 2. References 1. Discuss lesson objectives 2. Present Lecture 3. Ask and Answer Questions 4. Assign homework 1. Participate in discussion 2. Take notes 3. Ask and respond to questions The student will understand the effects of wind on maintaining equilateral radii on each side of a reference line. He or she will be able to make the necessary adjustments throughout the turns due to the airplane s changing position in relation to the wind.

2 Instructors Notes: Introduction: Attention This maneuver will provide a much better understanding of how the wind works in relation to turning the airplane. And, it s considered to be easier than the rectangular course you already learned. Overview Review Objectives and Elements/Key ideas What A maneuver in which the airplane s ground track describes semicircles of equal radii on each side of a selected straight line on the ground Why S-turns 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. How: 1. Selecting a Suitable Altitude A. Entry altitude should be 600 1,000 AGL i. +/- 100 restrictions a. At 600 AGL, there is no room for error below; At 1,000 AGL, there is no room above b. 800 AGL is a good altitude 2. Selecting a Suitable Reference Point A. A straight ground reference line or road that lies 90 o to the direction of the wind should be selected i. The reference can be a road, fence, railroad tracks, or section line that is easily identifiable ii. The line must be sufficiently long to make a series of turns B. Wind direction must be estimated (METAR, smoke, water, or a 360 o turn noting ground track) C. Only use references that clear of populated areas, obstructions, and anything that could pose a hazard D. The reference should allow for a nearby landing area in case of an emergency during the maneuver E. CE Selection of a ground reference without a suitable emergency landing area within gliding distance i. Part of poor planning, always be prepared for any type of emergency ii. Select a reference field and an emergency landing area 3. The Basics A. The maneuver consists of crossing the road at a 90 o angle and directly beginning a series of 180 o turns of uniform radius in opposite directions, re-crossing the road at a 90 o angle as each 180 o turn is completed B. To accomplish a constant radius ground track requires changing the roll rate and angle of bank i. Both will increase or decrease as GS increases or decreases a. On the downwind side, bank is steepest and gradually shallowed approaching the upwind C. The airplane is rolled from one bank directly into the opposite as the reference on the ground is crossed D. As with all ground ref maneuvers, attention must be divided between the ground track and the airplane i. Watch the ground ref line, maintain the ground track, fly the plane, instruments, and other traffic ii. CE - Poor planning, orientation, or division of attention a. Results in a failure to obtain the constant change of bank required to obtain a semicircular track b. Often the result of not selecting a good reference line or identifying wind direction 1

3 c. Ground track, airspeed, and altitude are poorly maintained E. Bank is constantly changing to track a constant radius turn on each side of the reference line 4. Prior to Entry A. Pre-Maneuver Checklist - Lights ON; Fuel Pump ON; Mixture FULL RICH; Gauges GREEN B. Clearing Turns C. Airspeed knots and trimmed for hands off, level flight 5. The Maneuver A. Entry i. The road/line should be approached on the downwind (perpendicular to the line), 800 AGL ii. CE - Faulty entry procedure a. Enter heading downwind, perpendicular to the reference line b. As soon as the lateral axis is over the line, roll into the steepest bank at a fairly rapid rate c. If the initial bank is too shallow, you will be pushed from the line, resulting in an excessive radius B. Downwind Side i. When directly over the first turn should be started immediately to the left ii. With the plane on a downwind, GS is greatest and the rate of departure from the road will be rapid a. The roll needs to be fairly rapid and the bank fairly steep (40/45 o ) to attain the proper crab angle This prevents the plane from flying too far from the road, establishing an excessive radius iii. Through the 1 st 90 o, the airplane s heading changes from a tailwind to a crosswind a. The crab angle is the greatest at the 90 o point b. GS becomes progressively less and the rate of departure from the road decreases Bank will be lessened slightly iv. After turning 90 o, the plane s heading becomes more and more of an upwind heading a. This decreases GS and the rate of closure with the road gets slower b. Slowly shallow the bank during the remaining 90 o This is to remove the crab angle completely Reach wings level as the turn is completed directly over the road C. Upwind Side i. At the instant the road is crossed, a turn in the opposite direction should be started ii. Since the plane is still flying directly into a headwind, the GS is low a. Therefore, the turn will have to be started with a shallow bank This will avoid an excessive rate of turn which would establish an excessively small radius b. Visualize the approach and increase bank slowly during the early part of the turn iii. The angle of bank should establish a ground track with an equal radios to the previous turn a. CE - An unsymmetrical ground track The first semicircle establishes the radii Visualize the ground track and plan for the wind s effect on the track iv. Since the plane is traveling from a headwind to a tailwind, the GS will increase, and after 90 o of turn, the rate of closure with the road will increase rapidly a. Therefore, the angle of bank/rate of turn will have to be progressively increased so the plane will have turned 180 o when it reaches the road v. Again, the rollout must be timed so straight and level is reached over and perpendicular to the road a. Judge the closure rate and increase bank to cross wings level D. CE - Improper correction for wind drift i. Not changing the bank will result in too small or large of a semicircle ii. Often there is a tendency to increase the bank too rapidly during the initial upwind turn 2

4 a. This prevents the completion of the 180 before re-crossing the road E. Constant Altitude i. Throughout the maneuver a constant altitude should be maintained a. Back pressure will have to be adjusted as bank is increased and decreased F. Airspeed i. Maintaining altitude should result in maintained AS (+/- 10 knots) ii. Check the ASI and make small power adjustments if necessary iii. Do not exceed 45 o of bank (this should keep the increased load factor from affecting AS) iv. CE - Failure to maintain selected altitude or airspeed a. Learn to divide attention between the ground reference and the line b. Maintaining altitude should result in maintaining airspeed as long as bank doesn t get too steep 6. Coordination A. Maintain coordinated flight through the changing bank i. Don t use only rudder to turn the plane B. CE - Uncoordinated flight control application i. Normally occurs when fixating on the ground reference line and not using coordinated controls ii. Don t yaw the nose to be directly over the reference line Common Errors: Faulty entry technique Poor planning, orientation, or division of attention Uncoordinated flight control application Improper correction for wind drift An unsymmetrical ground track Failure to maintain selected altitude or airspeed Selection of a ground reference line without a suitable emergency landing area in gliding distance Conclusion: Brief review of the main points Bank is constantly changing to track a constant radius turn on each side of the reference line as the airplane s position relative to the wind is changing. PTS Requirements: To determine that the applicant: 1. Exhibits instructional knowledge of the elements of S-turns across a road by describing: a. how to select a safe altitude. b. how to select a suitable ground reference line with consideration given to emergency landing areas. c. orientation, division of attention, and planning. d. configuration and airspeed prior to entry. e. entry procedure. f. wind drift correction. g. tracking of semicircles of equal radii on either side of the selected ground reference line. h. how to maintain desired altitude and airspeed. i. turn reversal over the ground reference line. j. coordination of flight controls. 2. Exhibits instructional knowledge of common errors related to S-turns across a road by describing: 3

5 a. faulty entry technique. b. poor planning, orientation, or division of attention. c. uncoordinated use of flight controls. d. improper correction for wind drift. e. an unsymmetrical ground track. f. failure to maintain selected altitude or airspeed. g. selection of a ground reference line where there is no suitable emergency landing area within gliding distance. 3. Demonstrates and simultaneously explains S-turns across a road from an instructional standpoint. 4. Analyzes and corrects simulated common errors related to S-turns across a road. 4

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