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Introduction:

  • By referencing the lift discussion, lift is perpendicular to the relative wind
  • When an aircraft is placed in a bank the resultant lift (the lift we talk about being perpendicular) is split between a vertical and horizontal component
  • The equal and opposite reaction to this side-ward force is centrifugal force, which is merely an apparent force as a result of inertia
  • The relationship between the aircraft's speed and bank angle determine the rate and radius of turns
  • Any time ailerons are used, adverse yaw is produced

WARNING:
All procedures here are GENERALIZED for learning.
Fly the maneuver in accordance with the Pilot Operating Handbook (POH)
and/or current Standard Operating Procedures (SOPs)


Instrument Flying Handbook. Figure 2-13, Forces In a Turn
Figure 1: Instrument Flying Handbook,
Forces In a Turn

Standard Rate Turns:

  • Entry:
    • Apply coordinated aileron and rudder pressures in the desired direction of turn
    • Use attitude indicator to establish the approximate angle of bank
    • Check the turn coordinator for coordination and rate of turn
    • Once established, the turn coordinator becomes the primary bank and the attitude now supports
    • During roll in, monitor altimeter, VSI and attitude for pitch adjustments due to loss of vertical lift
    • Airspeed becomes primary for power for constant airspeeds
  • Recovery:
    • Apply coordinated aileron and rudder opposite turn
    • Anticipate roll-out
    • Roll-out half of the bank angle before the desired heading
    • Attitude becomes primary bank while the airplane levels
    • The heading indicator becomes primary bank once established

Timed Turns:

  • Through the use of the clock and the turn coordinator, changes in heading can be made in as degrees over time
  • If using standard rate turn:
    • 30° = 10 seconds
    • 45° = 15 seconds
    • 90° = 30 seconds
    • 180° = 1 minutes
    • 360° = 2 minutes

Compass Turns:

  • There are a number of errors associated with using the magnetic compass to perform turns

  • If on a North heading, turning east or west, the compass indicates a lag, or shows a turn in the opposite direction initially
  • If on a South heading, turning east or west, the compass precedes the turn
  • When on an East or West heading, the compass indicates correctly in a turn in either direction
  • When on an East or West heading, accelerations result in a brief North indication
  • When on an East or West heading, decelerations result in a brief South indication
  • When on a North or South heading, no error results from diving, climbing, or changing airspeed
  • When rolling out to the north, lead the roll-out by your current latitude + half the bank angle
  • When rolling out to the south, pass the roll-out by your current latitude + half the bank angle

  • ANDS: Accelerate North, Decelerate South
  • UNOS: Undershoot North, Overshoot South

Steep Turns:

  • Any turn greater than standard-rate can be considered a steep turn
  • Enter exactly as you do a shallower turn but cross-check more rapid as the turn steepens

Climbing and Descending Turns:

  • Combine the technique used in straight climbs and descents with the various turn techniques

Change of Airspeed in Turns:

  • The angle of bank necessary for a given rate of turn is proportional to the true airspeed
  • Changes in airspeed mean the angle of bank must be varied to maintain constant rate of turn
  • Airspeed decreases, angle of bank decreases and pitch increases
  • Airspeed increases, angle of bank increase and pitch decrease
  • Altimeter is primary for pitch
  • Turn coordinator is primary for bank
  • Manifold pressure and tachometer is primary for power
  • Two methods to practice:
    • Airspeed is changed after the turn is established
    • The airspeed change is initiated simultaneously with the turn entry

Common Errors:

  • Pitch:
    • Preoccupation with bank control during turn entry and recovery
      • If bank control pressure and rate of bank change are consistent, a sense of the time required for an attitude change will be developed
    • Failure to understand or remember the need for changing the pitch attitude as the vertical lift component changes, resulting in consistent loss of altitude during entries
    • Changing the pitch attitude before it is necessary
    • Over-controlling the pitch changes
    • Failure to properly adjust the pitch attitude as the vertical lift component increases during the roll-out, resulting in consistent gain in altitude on recovery to headings
    • Failure to turn during turn entry and following turn recovery
    • Failure to maintain straight-and-level cross-check after roll-out
    • Erratic rates of bank change on entry and recovery, resulting from failure to cross-check the pitch instruments with a consistent technique appropriate to the changes in lift
  • Bank:
    • Over-controlling, resulting in overbanking upon turn entry, overshooting and undershooting headings, as well as aggravated pitch, airspeed, and trim errors
    • Fixation on a single bank instrument
    • Failure to check for precession of the horizon bar following recovery from a turn
      • If the heading indicator shows a change in heading when the attitude indicator shows level flight, the airplane is turning
      • If the ball is centered, the attitude gyro has precessed; if the ball is not centered, the airplane may be in a slipping or skidding turn
    • Failure to use the proper degree of bank for the amount of heading change desired
    • Failure to remember the heading to which the aircraft is being turned
    • Turning in the wrong direction due to misreading or misinterpreting the heading indicator or to confusion regarding the location of points on the compass
  • Power:
    • Failure to cross-check the airspeed indicator as pitch changes are made
    • Erratic use of power control due to either improper throttle friction, inaccurate settings, changing the airspeed, abrupt over-controlled pitch and bank changes, or failure to recheck the airspeed to note the effect of a power adjustment
    • Poor coordination of throttle control with pitch and bank changes
  • Trim:
    • Failure to recognize the need for a trim change
    • Failure to understand the relationship between trim and attitude/power changes
    • Chasing the vertical speed needle
  • Compass Turns:
    • Faulty understanding or computation of lead and lag
    • Fixation on the compass during the roll-out

Practical Test Standards/Airman Certification Standards:


References: