FAA Flight Instructor Airplane (FIA)Navigation and AirspaceMedium
A flight instructor reviews a compass deviation card with a student. The card reads: 'For MH 180, Steer 183.' To fly a magnetic heading of 180°, what compass heading should the student use?
- A177°
- B180°
- C183°
- D186°
Show answer & explanationAnswer & explanation
Correct answer: C. 183°
The deviation card directly lists the compass heading to steer for each magnetic heading; for MH 180°, the card specifies steering 183° on the compass to correct for deviation caused by aircraft magnetism and electrical equipment.
Why the other options are wrong
- A. 177° would be an overcorrection in the wrong direction.
- B. 180° is the magnetic heading, not the corrected compass heading.
- D. 186° applies deviation correction twice the required amount.
Compass Deviation Card
A placard near the magnetic compass listing the compass heading to steer for selected magnetic headings, correcting for deviation caused by onboard magnetic interference.
- Deviation differs from magnetic variation
- Card values vary by aircraft and electrical load
- Steer the listed compass heading to achieve desired magnetic heading
Memory trick: 'Deviation is Deceptive—check the card, not your gut.'