Magnetic Variation, Compass Deviation & TVMDC Calculator
Convert True Heading to Magnetic and Compass Headings with 'East is Least, West is Best' and Solar Kp index.
Input Parameters
Calculation Results
Formula & How Magnetic Variation, Compass Deviation & TVMDC Calculator Works
Magnetic poles do not align with geographic True North. Pilots and mariners must adjust for local Magnetic Variation (isogonic lines) and onboard electromagnetic Compass Deviation using the TVMDC method.
- Enter True Heading (Track/Route °): Input your target parameter value.
- Enter Magnetic Variation (°): Input your target parameter value.
- Enter Variation Direction (E/W): Input your target parameter value.
- Enter Compass Deviation (°): Input your target parameter value.
- Enter Deviation Direction (E/W): Input your target parameter value.
- Enter Solar Space Weather Kp Index (0-9): Input your target parameter value.
- Apply Formula: Calculate using
Magnetic = True ± Variation | Compass = Magnetic ± Deviation ('East is Least, West is Best'). - Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Frequently Asked Questions (FAQs)
What does 'East is Least, West is Best' mean in navigation?
When converting from True to Magnetic: subtract Easterly variation (East is Least) and add Westerly variation (West is Best).
How do solar flares affect compasses and GPS?
Coronal mass ejections cause geomagnetic storms (Kp 5-9) that disturb Earth's magnetic field, causing compass jitter, radio blackouts, and GPS positioning errors.
Authoritative Standards & Verified Reference Citations
Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:
CASR Part 91 general operating and flight rules, Part 121 fuel reserves, and flight crew licensing standards.
Aviation weather services, standard atmosphere (ISA) profiles, METAR/TAF aerodrome weather reports.
Aeronautical Information Publication (AIP), En Route Supplement Australia (ERSA), and airspace procedures.
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