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Obtengo rumbo en la carta 218º, declinación magnética corregida al año actual 10ºE y desvío (-6º). Indique el rumbo de aguja.With a charted true course of 218º, magnetic variation updated to the current year = 10º E, and compass deviation = –6º, what is the compass course?
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Correct answer: b) Ra = 214º
Why it is correct
Total compass error is Ct = variation + deviation = +10º + (−6º) = +4º. Subtracting total compass error from true course gives the compass course: Ra = Rv − Ct = 218º − 4º = 214º.
Why the others are not
- a) Does not apply Ra = Rv − (variation + deviation) = 218º − (+10º − 6º) = 214º.
- c) Does not apply Ra = Rv − (variation + deviation) = 218º − (+10º − 6º) = 214º.
- d) Does not apply Ra = Rv − (variation + deviation) = 218º − (+10º − 6º) = 214º.
How to work it out in the exam
- Compute total compass error: Ct = +10º − 6º = +4º.
- Subtract Ct from true course: Ra = 218º − 4º = 214º.
Where this question comes from
- Región de Murcia · 2023 · 3ª convocatoria · PER Tipo 1 · question 42 Official paper · Official answer key
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Pending instructor review. Machine translation, not reviewed.