True course to compass heading
From true course through the wind correction, variation, and your compass deviation card to the heading to fly on the compass, each step shown.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
Fly 74.5° on the compass: 75° magnetic, with 0.5° of deviation.
| Step | Heading |
|---|---|
| true course | 70.0 deg |
| + wind correction: true heading | 65.0 deg |
| − variation: magnetic heading | 75.0 deg |
| − deviation: compass heading | 74.5 deg |
- True heading
- Magnetic heading
- Deviation
Provenance
- Computed by
- aviation.wind.heading-chain 1.0.0, core 0.1.0
- Model
- True heading = true course + wind correction; magnetic = true − variation (east positive: "east is least"); compass = magnetic − deviation, the deviation read from the card by linear interpolation between its two nearest headings, around the circle (PHAK, navigation)
- Accuracy
- Exact arithmetic; the deviation is as good as the card
- Notes
- 1 shown with the answer
- Cites
- Federal Aviation Administration, Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: True heading = true course + wind correction; magnetic = true − variation (east positive: "east is least"); compass = magnetic − deviation, the deviation read from the card by linear interpolation between its two nearest headings, around the circle (PHAK, navigation)
Accuracy: Exact arithmetic; the deviation is as good as the card
Worked example: Course 070° true, 5° left wind correction, 10° W variation, and a card. Source: add-aviation-suite deviation-card scenario: magnetic 075°, between +2° at 060° and -1° at 090°, reads +0.5°; compass 074.5°. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Deviation card
- 030 deg, 1 deg 060 deg, 2 deg 090 deg, -1 deg 120 deg, -2 deg
- True course
- 070 deg
- Variation
- -10 deg
- Wind correction angle
- -5 deg
You get
- Compass heading
- 74.5°
- True heading
- 65°
- Magnetic heading
- 75°
- Deviation
- 0.5°
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-19, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 8 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Federal Aviation Administration, FAA-H-8083-25C. Navigation chapter (magnetic variation, compass deviation and the deviation card, and the compass heading).
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.
Learn the concept: The wind triangle explained