Instrument Scanning

Instrument Scanning

Instrument Scanning basic theory

  • The basic performance formula for attitude instrument flying, as well as flying by visual outside reference is:
    • Power + attitude = Performance.
Flight instruments are divided into the following three categories.
  • Pitch Instruments:
    • Attitude indicator (AI).
    • Alitmeter (ALT).
    • Airspeed indicator (ASI).
    • Verical speed indicator (VSI).
  • Bank instruments:
    • Attitude indicator (AI).
    • Heading indicator (HI).
    • Turn coordinator (TC) or Turn and bank indicator.
    • Magnetic compass.
  • Power intruments:
    • Manifold pressure gauge (MP).
    • Tachometer (RPM).
    • Airspeed indicator (ASI).
  • ATTITUDE INDICATOR is the primary instrument to indicate aircraft attitude, it shows: Pitch and Bank attitude.

Instrument                              direct information                            Indirect information

Airspeed indicator                   Airspeed                                               Pitch attitude.

Altimeter                                    Altitude                                                Pitch attitude.

Vertical speed Indicator          climb/descent rate                             Pitch attitude.

Heading Indicator                     Heading                                               Bank attitude.

Turn and slip coordinator        Yaw, coordination                             Bank attitude.

Turn coordinator                       Yaw, roll, coordination                     Bank attitude.   

Magnetic compass                    heading                                               Bank attitude.

Instrument Scan

  • Focus primarily on the attitude indicator.
  • your eyes never travel directly between the flight instruments but move by way of the attitude indicator.
  • Other instruments are scanned less frequently for backup information.
  • To develop the technique  of always referring to the correct instrument at appropriate time, you must continually ask yourself the question:
    • What information do I need ?
    • Which instruments give me the needed information ?
    • Is the information reliable ?

Review questions

  • What is the main instrument during flight instrument ?
  • What are the different categories of flight instruments ?
  • What are the questions you have to ask yourself to develop a good scan technique ?