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Teaching and Learning Flying - Airplane Instrument Rating

Partial Panel (Unusual Attitude Recovery, Timed Turns, Magnetic Compass Turns)


DEFINITION

Partial panel refers generally to AIF after loss of one or more flight instruments. This lesson emphasizes AIF after loss of the two vacuum pump-driven gyroscopic instruments, the AI and HI.
Unusual attitudes are those not normally required for instrument flight. Recovery involves prompt return to SLF.
Timed turns are turns in which the clock and turn coordinator are used to change heading a definite number of degrees in a given time.
Magnetic compass turns are turns to headings using the magnetic compass.

SAFETY FACTORS

Competence gained through knowledge and practice of partial panel AIF allows continued safe flight after instrument failures that might otherwise lead to confusion, disorientation, unusual attitudes and disaster. Proficiency in partial panel flight, including flying a nonprecision approach, is essential for safe AIF in IMC.
With knowledge and practice, unusual attitudes can be safely and efficiently recovered to SLF rather than lead to excessive speed, airframe loading, or altitude loss.
Timed turns allow safe, accurate turns to headings without use of the HI during partial panel AIF.
Knowledge and skill in magentic compass turns enhance the safety and accuracy of partial panel AIF.

TOLERANCES

Instrument Rating PTS (FAA-S-8081-4D)
VII. D. Approach with loss of primary flight instrument indicators
To determine that the applicant:
  1. Exhibits adequate knowledge of the elements relating to recognizing if primary flight instruments are inaccurate or inoperative, and advise ATC or the examiner.
  2. Advises ATC or examiner anytime that the aircraft is unable to comply with a clearance.
  3. Demonstrates a nonprecision instrument approach without the use of the primary flight instruments using the objectives of the nonprecision approach TASK (AREA OF OPERATION VI, TASK A)
IV. B. Recovery from unusual flight attitudes
To determine that the applicant:
  1. Exhibits adequate knowledge of the elements relating to attitude instrument flying during recovery from unusual attitudes (both nose-high and nose-low).
  2. Uses proper instrument cross-check and interpretation, and applies the appropriate pitch, bank, and power corrections in the correct sequence to return the aircraft to a stabilized level flight attitude.

OBJECTIVES

To encourage mastery of partal panel AIF (including nonprecision approaches), recovery from unusual attitudes, timed turns and magnetic compass turns to increase the safety of flight
To develop student knowledge and skill in partial panel AIF (including nonprecision approaches), recovery from unusual attiudes, timed turns and magnetic compass turns to meet the instrument pilot PTS

PROCEDURES

Preflight
Discussion
Partial Panel Unusual attitudes
  • Conditions leading to unusual attitudes
  • Procedure using partial panel for recovery from nose-high and nose-low unusual flight attitudes
      1) Recognize unusual attitude
        a) Nose high
    Nose High Unusual Attitude Partial Panel
          1) Airspeed too slow, decreasing (ASI)
          2) ALT increasing
          3) TC shows turn
          4) VSI positive rate, climb

        b) Nose low
    Nose Low Unusual Attitude Partial Panel
          1) Airspeed too fast, increasing (ASI)
          2) ALT decreasing
          3) TC shows turn
          4) VSI negative rate, descent
      2) Recover using ASI, TC, ALT, VSI (and ignoring AI and HI, which may have failed), so full and partial panel recoveries are the same
        a) Nose high recovery
          1) Add power
          2) Lower nose
          3) Level wings
        b) Nose low recovery
          1) Reduce power
          2) Level wings
          3) Raise nose
Timed turns
  • Full panel TC calibration both directions
  • Timed turns to compass headings
Magnetic compass turns Inflight Postflight
    Critique student performance

COMMON ERRORS

    Partial Panel
    • Slow to recognize/confirm vacuum system instrument failure
    • Failure to notify ATC of situation
    • Failure to adequately transition from full to partial panel condition
    • Failure to ignore/cover failed instruments
    • Poor aircraft control on partial panel due to full panel overdependence on AI
    Unusual Attitudes
    • Airplane not properly trimmed (may end up in unusual attitude)
    • Disorganized cockpit
    • Slow cross-check and fixations
    • Attempted recovery by sensory sensations other than sight (trust your instruments)
    • Failure to practice basic AIF skills
    • Incorrect interpretation of the flight instruments
    • Inappropriate application of the controls
      • Nose high: power-nose-wings
      • Nose low: power-wings-nose
    Timed turns/Compass turns
    • Incorrect calibration procedures
    • Improper timing
    • Uncoordinated use of controls
    • Improper trim control
    • Faulty understanding or computation of lead or lag in compass turns
    • Fixation on compass during roll-out of compass turn
        After roll-out, cross-check for SLF, then check MC heading
References
Greg Gordon MD, CFII
Updated: