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DGCA Technical General · 54 questions

Compass: DGCA Technical General Questions and Answers

54 practice questions on Compass with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.

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About this topic

Use this page to revise Compass for the DGCA Technical General paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 54 questions in the TrueHeading bank for this topic.

In short: Dip makes the compass card tilt, which causes errors that depend on heading and latitude (northern hemisphere).

Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.

Key concepts: Compass

3 ideas to know cold.

Magnetic compass turning and acceleration errors?

Dip makes the compass card tilt, which causes errors that depend on heading and latitude (northern hemisphere).

  • UNOS: turning towards North, roll out before the compass reads north (undershoot); towards South, roll out after (overshoot)
  • ANDS: on an east or west heading, accelerating shows a turn towards north; decelerating shows a turn towards south
  • A compass swing finds deviation and the deviation card records it
TMCheadingvardevT = true N · M = magnetic N · C = compass Nvar east, magnetic least · var west, magnetic best

Remote-indicating compass?

A flux valve senses the magnetic field and a gyro stabilises the heading.

  • Mounted away from aircraft magnetism (wing tip)
  • Slaved gyro compass corrects for drift

Why does the magnetic compass err?

Variation, deviation, dip (turning and acceleration errors), and swirl.

  • UNOS: Undershoot North, Overshoot South
  • ANDS: Accelerate North, Decelerate South
  • Compass swing reduces deviation

Practice questions: Compass

Tap “Show answer” after you have tried each one.

Q1True heading 160°, variation 8°E, deviation 2°E. The compass heading to steer is:

  1. 154°
  2. 170°
  3. 150°
  4. 166°
Show answer

Answer: C. 150°

True 160° → magnetic 152° (variation E: subtract) → compass 150° (deviation E: subtract). TVMDC: from true to compass, West is added, East is subtracted.

Q2True heading 315°, variation 4°E, deviation 5°W. The compass heading to steer is:

  1. 316°
  2. 324°
  3. 314°
  4. 306°
Show answer

Answer: A. 316°

True 315° → magnetic 311° (variation E: subtract) → compass 316° (deviation W: add). TVMDC: from true to compass, West is added, East is subtracted.

Q3True heading 120°, variation 3°E, deviation 2°W. The compass heading to steer is:

  1. 125°
  2. 119°
  3. 121°
  4. 115°
Show answer

Answer: B. 119°

True 120° → magnetic 117° (variation E: subtract) → compass 119° (deviation W: add). TVMDC: from true to compass, West is added, East is subtracted.

Q4True heading 255°, variation 15°E, deviation 2°W. The compass heading to steer is:

  1. 242°
  2. 272°
  3. 238°
  4. 268°
Show answer

Answer: A. 242°

True 255° → magnetic 240° (variation E: subtract) → compass 242° (deviation W: add). TVMDC: from true to compass, West is added, East is subtracted.

Q5True heading 075°, variation 6°W, deviation 1°W. The compass heading to steer is:

  1. 068°
  2. 080°
  3. 070°
  4. 082°
Show answer

Answer: D. 082°

True 075° → magnetic 081° (variation W: add) → compass 082° (deviation W: add). TVMDC: from true to compass, West is added, East is subtracted.

Q6True heading 035°, variation 12°E, deviation 1°E. The compass heading to steer is:

  1. 022°
  2. 048°
  3. 024°
  4. 046°
Show answer

Answer: A. 022°

True 035° → magnetic 023° (variation E: subtract) → compass 022° (deviation E: subtract). TVMDC: from true to compass, West is added, East is subtracted.

Q7Compass heading is 018°, deviation 5°W, variation 2°E. The true heading is:

  1. 025°
  2. 011°
  3. 015°
  4. 021°
Show answer

Answer: C. 015°

Compass → magnetic → true (TVMDC read backwards): from compass to true, East is added and West is subtracted, first for deviation, then for variation.

Q8Compass heading is 169°, deviation 1°W, variation 12°E. The true heading is:

  1. 182°
  2. 180°
  3. 158°
  4. 156°
Show answer

Answer: B. 180°

Compass → magnetic → true (TVMDC read backwards): from compass to true, East is added and West is subtracted, first for deviation, then for variation.

Q9Magnetic dip is the angle between:

  1. the compass card and the lubber line
  2. the compass and true north
  3. the earth's field and true north
  4. the earth's magnetic field and the horizontal
Show answer

Answer: D. the earth's magnetic field and the horizontal

Dip is zero at the magnetic equator and 90° at the magnetic poles.

Q10Acceleration error on an easterly or westerly heading in the northern hemisphere: acceleration gives an apparent turn towards:

  1. north
  2. east
  3. west
  4. south
Show answer

Answer: A. north

Remember ANDS: Accelerate North, Decelerate South.

Q11A deviation card (compass correction card) shows:

  1. the variation
  2. the fuel flow
  3. the track
  4. the corrections to apply to compass headings, at intervals of 30°
Show answer

Answer: D. the corrections to apply to compass headings, at intervals of 30°

Residual deviation after compass swinging.

Q12The flux valve (flux gate) senses:

  1. the vertical component only
  2. the gravity
  3. the airspeed
  4. the horizontal component of the earth's magnetic field
Show answer

Answer: D. the horizontal component of the earth's magnetic field

It is located in the wing tip away from magnetic interference.

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