FAA Aircraft Dispatcher (ADX)Flight Planning and PerformanceMedium
A dispatcher computes a true course of 095° for a planned route. The magnetic variation for the area is 6°E. What magnetic course should be used for flight planning?
- A083°
- B095°
- C089°
- D101°
Show answer & explanationAnswer & explanation
Correct answer: C. 089°
Using the rule 'East is least, West is best,' easterly variation is subtracted from true course to get magnetic course: 095° - 6° = 089°.
Why the other options are wrong
- A. This subtracts too large a value, not matching the given 6° variation.
- B. This ignores variation entirely.
- D. This adds the variation instead of subtracting; incorrect for easterly variation.
True to Magnetic Course Conversion
Magnetic course is derived from true course by applying magnetic variation: subtract easterly variation, add westerly variation.
- East is least (subtract easterly variation)
- West is best (add westerly variation)
- Variation values come from isogonic lines on charts
Memory trick: East is least, West is best — apply variation to get your magnetic course.