Pilot Courses of Instruction

Flight Instruments

Magnetic Compass

Compass Errors

"Magnetic Dip"

1. Turning Error

   ANDS - Anticipate North, Delay South

   Latitude +/- 1/2 angle of bank

   • Turns to North:
     • Compass LEADS turn
     • Roll-out before North
     • Latitude + 1/2 angle of bank
       For example,

       • turning to a heading of North (360°) from a heading of West (270°)
       • at 40°N latitude, with a bank angle of 20°
       • 40 (°N latitude) + 1/2 of 20 (°bank angle) = 50°
       • Roll-out prior to 360° on a heading of 310°
   • Turns to South:
     • Compass LAGS turn
     • Roll-out after South
     • Latitude - 1/2 angle of bank
       For example,

       • turning to a heading of South (180°) from a heading of West (270°)
       • at 40°N latitude, with a bank angle of 20°
       • 40 (°N latitude) - 1/2 of 20 (°bank angle) = 30°
       • Roll-out after 180° on a heading of 150°
   • No error on turns to East or West

2. Acceleration Error

   ANDS - Accelerate North, Decelerate South

   • Accelerating:
     • On Easterly or Westerly headings:
       • Compass indicates a turn to the north
   • Decelerating:
     • On Easterly or Westerly headings:
       • Indicates a turn to the south
   • No error on headings of North or South

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