Trimming The Aircraft

Aircraft trim reduces sustained control force for a selected flight condition, lowering workload without replacing active use of the primary flight controls.

Trimming The Aircraft

Introduction to Trimming The Aircraft

  • Trimming is a basic, but critical skill for pilots to understand and practice
  • Returning to the basics, pitch and power determine aircraft performance, while changes in either may require control-surface deflection to maintain the desired flight condition.
  • Trimming allows the pilot to relieve sustained control pressure after establishing the desired flight condition.
    • A change in power, speed, configuration, loading, or flight phase may change the trim required.
  • It generally does not come easy to most pilots and therefore requires attention and practice
  • Test your understanding of Trimming The Aircraft by completing the knowledge quiz, applying your knowledge in the interactive scenario, comparing your performance against the applicable Airman Certification Standards, and concluding with the topic summary to reinforce the key concepts before moving on to the next lesson.

  • WARNING:
    All procedures are GENERALIZED.
    Use the Pilot Operating Handbook (POH) procedures for specific aircraft performance and limitations.
    and/or current Standard Operating Procedures (SOPs).
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    Trimming The Aircraft

    Trimming The Aircraft Key Highlights

    • Aircraft trim systems reduce pilot control pressures and help maintain desired flight attitudes and performance conditions.
    • Proper trimming improves aircraft stability, reduces pilot workload, and enhances flight precision during all phases of flight.
    • Elevator trim is commonly used to maintain pitch attitude and relieve longitudinal control forces.
    • Aileron and rudder trim systems may help compensate for asymmetric loading, fuel imbalance, or aerodynamic forces.
    • Pilots should establish the desired aircraft attitude and performance before applying trim corrections.
    • Improper trim settings can lead to excessive control pressures, unstable flight conditions, or pilot-induced oscillations.
    • Trim adjustments are frequently required during changes in airspeed, power, configuration, or flight phase.
    • Runaway trim malfunctions can create serious control difficulties and require prompt corrective action.
    • Pilots should maintain awareness of trim position during takeoff, approach, landing, and emergency operations.
    • Understanding aircraft trimming improves flight control precision, workload management, and overall flight safety.
    Trimming The Aircraft

    Trim Basics

    • Trim refers to employing adjustable aerodynamic devices on the aircraft to adjust forces so the pilot does not have to manually hold pressure on the controls
    • Depending on the airplane, trim may use a tab, an adjustable stabilizer, a spring or bungee system, or another approved mechanism.
      • Pitch trim is common; rudder or aileron trim may or may not be installed. Verify the actual system in the POH or AFM.
    • A conventional trim tab generally moves opposite the associated primary surface, but servo tabs, anti-servo tabs, stabilizer trim, and spring systems operate differently.
    • The force of the airflow striking the tab causes the main control surface to be deflected to a position that corrects the unbalanced condition of the aircraft
    • Airspeed changes alter aerodynamic control forces and commonly require retrimming; the amount and direction depend on aircraft design, power, configuration, and loading.
    • An aircraft properly trimmed in pitch seeks to return to the original speed before the change due to its stability.
    • Trimming is a constant task as soon as you change any power setting, airspeed, altitude, or configuration
    • Proper trimming decreases pilot workload allowing for attention to be diverted elsewhere, especially important for instrument flying
    • Proper trim reduces steady force in the pattern, but the pilot must continue using the primary controls to maintain the desired attitude, airspeed, and flight path.
    • Use the sequence control, power, configuration, then trim: establish the desired condition first and trim off the remaining sustained pressure.
    Trimming The Aircraft

    Trimming Procedure

    1. Set and steady your airspeed (can be in a climb, descent, or level)
      • After changing pitch, power, or configuration, maintain the desired condition with the primary controls and allow the response to develop as appropriate before trimming off sustained pressure; there is no universal five-second rule.
    2. Set trim by gradually reducing the sustained control force while continuing to maintain the desired flight path with the primary controls.
      • If the nose feels heavy, trim nose-up.
      • If the nose feels light, trim nose-down.
    3. Reduce pressure on the controls, possibly by momentarily releasing the control yoke.
      • If the nose remains level, the trim is properly set.
      • If the nose rises, add nose-down trim;
      • if it falls, add nose-up trim.
    4. Set the attitude, then trim off the pressure with the appropriate correction
      • Small applications of trim make large changes in the pitch attitude.
        • Be patient and make multiple changes to trim, if necessary.
    5. Repeat steps 3 - 4 until the aircraft maintains the desired attitude
      • Once the aircraft is in trim, relax on the control yoke as much as practicable.
        • When pressure is held on the yoke, unconscious pressures are applied to the elevator and ailerons, which displaces the aircraft from its desired flightpath.
        • Proper trim should leave little sustained control force, but it is not an altitude-hold system and does not relieve the pilot of continuous monitoring and control.
    Trimming The Aircraft

    Trimming by Control Surface

    • Installed trim systems vary by airplane.
      • When rudder trim is installed, set it to relieve the sustained rudder force required for coordinated flight; direction and amount are aircraft- and condition-specific.
    • Elevator trim:
      • Use the primary pitch control to establish the desired attitude and airspeed, then apply the installed pitch-trim system in the direction that relieves the sustained force.
    • Aileron:
      • Used as required to level an aircraft
    • Trim Tabs:
      • A servo trim tab moves opposite of the surface it is trimming
      • An anti-servo trim tab moves with the surface it is trimming
    Trimming The Aircraft

    Trimming Common Errors

    • Over controlling
    • Using trim to fly the airplane instead of first establishing the desired attitude with the primary flight controls.
    • Making repeated trim adjustments before the desired attitude and airspeed stabilize; establish the flight condition first, then trim off the remaining control pressure.
    Trimming The Aircraft

    Trimming The Aircraft Interactive Scenario

    Interactive Scenario

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    Trimming The Aircraft

    Trimming The Aircraft Knowledge Check

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    Core Knowledge Review

    Review foundational knowledge, key concepts, and practical considerations. Topic: Trimming The Aircraft.

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    Why Take a Quiz?

    Quizzes reinforce key concepts, identify knowledge gaps, and build confidence for real-world decisions. Quiz material is representative of the information provided here and is not based on or sourced from the Federal Aviation Administration test bank.

    Trimming The Aircraft

    Trimming Airman Certification Standards

    Trimming The Aircraft

    Trimming The Aircraft Conclusion

    Trimming The Aircraft

    Trimming The Aircraft References