Departure of a Traverse Leg
Worked example: 30 m of departure on a 60 m course → azimuth 30° — press Try an example to run it live, then adjust anything.
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UniversityApplied Field Engineering
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Departure of a Traverse Leg explained
Departure is the east-west partner of latitude, and with azimuths measured from north it takes the sine. Together the pair converts a field book of distances and directions into coordinate differences that can be added up, adjusted and plotted. Positive departures run east, negative run west, and the sign falls out of the sine automatically for azimuths past 180°.
The reason both components matter is that either one alone is ambiguous. A course with a departure of 125 ft on a 250 ft leg could be heading at azimuth 30° or at 150° — north-east or south-east — and only the latitude settles it. That is precisely why the arcsine brain here is flagged: it returns the northern branch and leaves the choice to you. A worked example: a 250 ft course at azimuth 30° has a departure of 250 sin 30° = 125 ft east and a latitude of 250 cos 30° = 216.5 ft north, and the two squared and added return the 250 ft you started with, which is the first arithmetic check a party chief runs.
Departure of a Traverse Leg formula
- = Departure (east-west component) (m)
- = Course length (m)
- = Azimuth from north (°)
Missing one of these? Work it out first, then come back
- Course length — Latitude of a Traverse Leg, Concrete Volume with Waste Allowance
- Azimuth from north — Latitude of a Traverse Leg, Back Azimuth