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Basic Attitude Instrument Flight

Introduction:

  • Attitude instrument flying is defined as control of an aircraft's spatial position by using instruments rather than ground reference

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)


Primary and Supporting Method:

  • For any maneuver of flight condition, the pitch, bank, and power control requirements are most clearly indicated by certain key instruments
    • These are your primary instruments while those that back up these indications will be supporting
  • Pitch Instruments:
    • Attitude indicator
    • Altimeter
    • Airspeed Indicator
    • Vertical Speed Indicator
  • Bank Instruments:
    • Attitude Indicator
    • Heading Indicator
    • Magnetic Compass
    • Turn Coordinator
  • Power Instruments:
    • Airspeed Indicator
    • Engine Instruments
      • Manifold Pressure
      • Tachometer
      • Engine Pressure Radio (EPR)

Basic Attitude Instrument Flying Skills:

  • Cross Checking:
    • Human error, instrument error, and atmospheric changes make it impossible to establish an attitude and keep performance constant
    • Cross-checking is the continuous scanning of flight instruments to maintain desired attitude and performance
      • Selected Radial Cross-Check:
        • 80-90% of scan is focused on attitude indicator
        • Scan begins with attitude and branches out to various other instruments but scan always return to attitude before checking the next instrument branches will depend on maneuver
      • Rectangular Cross-Check:
        • Scan moves in a clockwise or counter clockwise direction around the basic six pack, thus creating a rectangular pattern
        • Gives equal weight to each instrument
        • Can lengthen time between checking instruments critical for maneuver being performed
      • Common Cross-Check:
        • Common cross-check for a beginner is rapidly looking at different instruments without knowing why or what they are looking for
        • With experience the common cross-check becomes habit, you look at the instruments needed for the given situation, you know what to look for and how long to look
  • Instrument Interpretation:
    • Understanding the information provided by cross-checking
    • Requires through study and analysis
    • An understanding of both construction and operating principles is necessary
    • The more a pilot knows about the instruments in his or her plane the better they will be able to understand the information being given to them
      • By knowing trends and limitations of instruments a pilot will know what other instruments to cross-check to get the complete picture
    • Such things as knowing what pitch attitudes to use for a given rate of climb or what power settings will give an approximate airspeed will reduce pilots workload
  • Aircraft Control:
    • Taking the instrument information that has been interpreted and making physical adjustments to flight controls in response
    • When using instruments instead of outside references the control inputs are the same, but must be smooth and precise
    • There are four components to aircraft control:
      • Pitch Control:
        • Controlling the rotation of the aircraft around the lateral axis by movement of the elevators in response to instrument interpretation
      • Bank Control:
        • Controlling angle made by the wing and the horizon, after interpreting appropriate instruments movement of the ailerons to roll the aircraft about its longitudinal axis
      • Power Control:
        • Interpretation indicates need for adjustment in thrust
      • Trim Control:
        • Trim removes control pressure once desired attitude is attained
        • Improper trim will cause a need for constant force need on the controls, this adds distraction and leads to abrupt and unintentional attitude changes

Common Errors:

  • Fixation:

    • Tendency to stare a one instrument and negate the rest
      • If off altitude, you may stare at altimeter until desired altitude is regained
      • While a change in bank is occurring tendency will be to stare at heading indicator until reaching desired heading, this will negate all power and pitch instruments

  • Omission:

    • Leaving a particular instrument out of scan
      • In a climb you may reference altitude, airspeed, and vertical speed but inadvertently omit altimeter

  • Emphasis:

    • Checking one or a few instruments more readily than the rest
    • Generally the case with less experienced pilots because they may not understand an instrument fully, and tendency is to rely on what you know
    • Students may be able to hold altitude well by use of altimeter but can not do so with only using the attitude indicator
  • With low time pilots there is a tendency to either not believe instruments because they do not agree with what they "feel" is right or the pilot will omit instrument errors
  • With more experienced pilots, a common interpretation error is the tendency to carry over knowledge from one plane to the next
    • Example: flying a low performance plane like a high performance one

Airman Certification Standards:

References:

  • Instrument Flying Handbook