The six primary instruments (the “six-pack”) are the Attitude Indicator (AI), Heading Indicator (HI), Turn Coordinator, Airspeed Indicator, Altimeter, and the Vertical Speed Indicator (VSI).

  • pilot-static system: air speed indicator, vertical speed indicator (VSI), altimeter
  • The gyroscopic instruments include the Attitude Indicator (AI), Heading Indicator (HI), and Turn Coordinator.
    • use a mechanical gyroscope that is either pneumatically (vacuum) or electrically driven. The gyroscope consists of a spinning disc that rotates freely around specific axes, depending on the instrument.

Pitot-Static Instruments

  • pitot tube clogged: altimeter inoperative.
  • static vents clogged: airspeed, altimeter, vertical speed inoperative.


3 speed: indicated, calibrated, true

  • indicated (IAS): what you read
  • calibrated (CAS): corrects based on the aircraft?
  • true (TAS): corrects calibrated airspeed for variations in air density


  • white arc: the flap operating range.
    • lower: V_s0 power-off stalling speed, full flaps, max weight
  • green arc: the normal operating range.
    • lower: V_s1, power-off stalling speed, flaps up, max weight.
  • yellow arc: the caution range; should only be flown in smooth air.
    • lower: V_NO, max structural cruising speed.
    • upper (red line): V_NE, never exceed speed

Other speed:

  • V_A: maneuvering speed. VA changes depending on the weight of the airplane, is not marked
    • No full or abrupt control movements allowed above this airspeed.
  • V_Y: the best rate-of-climb speed (the most altitude in a given period of time)
  • V_X: the best angle-of-climb speed (the most altitude in a given distance)