1. Turning Errors 

a. The magnetic compass gives erroneous turn indications when the aircraft is flying near headings of north or south. 
b. The magnitude of error varies with angle of bank and proximity to north or south headings. The error becomes progressively smaller as east or west headings are approached. The error also depends on the latitude at which the aircraft is flying. 
c. All methods of compensating for turn error in medium latitudes are based on using a definite and constant bank between 15° and 18°. 

2. Northerly Turning Error 

a. Fly a north heading long enough for the compass to settle down (wings must be level). 
b. Enter a turn toward the west. The compass immediately indicates a turn in the opposite direction, i.e., toward the east. (Return to the north heading.) 
c. Enter a turn toward the east. The compass indicates a turn toward the west. (Return to the north heading.) 
d. Enter a very shallow banked turn toward the west. The compass indicates momentarily that a straight course is being maintained. Point out that the wings must be level to avoid turn errors. Repeat the demonstration in a shallow turn toward the east. 
e. Enter a steep turn. The compass lags excessively and may swing completely around in the opposite direction from the turn. 

3. Southerly Turning Error 

a. Fly a south heading and let the compass settle down (wings must be level). 
b. Enter a turn toward the west. The compass indicates a much faster turn in the same direction. (Return to the south heading.) 
c. Enter a turn toward the east. The compass indicates a much faster turn in the same direction. 
d. The wings must be level to avoid compass turn errors. 

4. Acceleration and Deceleration Error 

a. Fly a heading of east. 
b. Increase airspeed in level flight to show acceleration error - compass indicates a turn toward north. 
c. Reduce airspeed in level flight to show deceleration error - compass indicates a turn toward the south. 
d. Lower the nose at a constant power setting - show acceleration error.
e. Raise the nose at a constant power setting - show deceleration error. 
f. Fly a heading of west and repeat the above demonstration. 
g. Explain that the magnitude of the error depends on the rate of acceleration or deceleration. To read the compass accurately on easterly and westerly headings, the airspeed must be constant. 
h. Acceleration and deceleration errors are not present in constant airspeed climbs and descents. 
i. Show that acceleration and deceleration errors are not present on north and south headings. 
j. Show that turn errors are not present on east and west headings. 

5. Turns to Magnetic Compass Headings 

a. Turn to a heading of north, using 15° to 18° of bank. Lead the heading an amount equal to the latitude plus half the angle of bank. 
b. Turn to heading of south, using 15° to 18° of bank. Over-shoot the heading an amount equal to the latitude minus half the angle of bank. 
c. From south, then from north, turn to a heading of east. Lead the heading approximately 5° when turning from a heading of south to east and approximately 10° when turning from a heading of north to east. 
d. Turn to a heading of west, using the procedure given above. 
e. Show that lead or lag must be interpolated when turning to intermediate headings. 

6. Student Practice - Make turns to magnetic compass headings: 

a. Without the heading indicator. 
b. Without the heading indicator and attitude indicator. 

Timed Turns 

1. Calibration of the Miniature Aircraft of the Turn Coordinator 

a. With all instruments available, establish a standard rate turn as indicated by the miniature aircraft of the turn coordinator. 
b. As the clock second hand passes a cardinal point (12, 3, 6, or 9), check the heading indicator. 
c. Check for a turn of 30° each 10 seconds (no lag, since timing is started after turn is established). 
d. Make necessary changes in indicated rate (miniature aircraft position) to produce a standard rate turn. 
e. Calibrate miniature aircraft of turn coordinator both right and left. 
f. Note exact deflection of miniature aircraft and use during all timed turns. 

2. Timed Turns with All Instruments Available 

a. Enter a standard rate turn when the clock second hand passes a cardinal point (12, 3, 6, or 9). 
b. The first 30 seconds is used to establish the turn properly. 
c. Check the heading indicator to see whether the rate of turn is proper. It should indicate a turn of 90° minus the number of degrees lag for the angle of bank used (lag will be approximately one-half the degree of bank). 
d. Demonstrate how the angle of bank is increased or decreased to compensate for any error. 
e. After the first 30 seconds, the heading indicator should be checked against the clock every 15 seconds. 
f. Time is started when pressure is applied to roll into a turn and is stopped when pressure is applied to roll out. 
g. With all instruments available, roll out on the desired heading regardless of time. 

3. Timed Turns without the Heading Indicator and Attitude Indicator 

a. Enter a standard rate turn, using the miniature aircraft of the turn coordinator as the primary bank instrument while in the turn. 
b. Turn for 30 seconds, using a constant miniature aircraft position. 
c. At the end of 30 seconds, roll out of the turn at the same rate you made the roll-in. 
d. With the wings level and the miniature aircraft of the turn coordinator indicating zero rate of turn, the magnetic compass should indicate that a turn of 90° has been made. 
e. For small changes in heading, use a half-standard-rate turn as indicated by the miniature aircraft of the turn coordinator. 

4. Student Practice. Make timed turns at different airspeeds: 

a. With all available instruments. 
b. Without the heading indicator. 
c. Without the heading indicator and attitude indicator.