NorthStar 961 Reference Manual page 293

Distance,
bearing, and
steering
calculations
961/962 Operations and Reference Manual, Rev. A
2. Press the CURSOR PAD left or right or press the LEFT
ARROW or RIGHT ARROW keys to select TRUE, AUTO, or
MAN (for manual).
3. When done, press the ACCEPT key (or CANCEL to leave
the option unchanged).
If you've chosen MAN, press the EDIT DATA key, then use
the KEYPAD to enter the variation for your area. If you
make a mistake during data entry, press the LEFT
ARROW and RIGHT ARROW keys to position the cursor.
To change between east and west variation (west is
appropriate on the East coast of the U.S.), press the
ARROW keys to position the cursor, then use the
KEYPAD to choose either E or W.
4. When done, press the ACCEPT key (or CANCEL to leave
the option unchanged).
5. Press RETURN to go back to the SETUP MENU screen.
The shortest distance between any two points on the surface
of a sphere, appearing as a curved line on a Mercator grid, is
known as the great circle. By comparison, a constant direction
to your destination is known as a rhumb line, which appears
as a straight line on a Mercator grid. Over long distances, a
rhumb line provides a somewhat longer route of travel than a
great circle route. However, if a great circle route takes you too
close to bad weather or an unavoidable land mass, you may
want to follow a rhumb line. Rhumb line navigation is the
default method for calculating distance, bearing, and steering
(XTE) to waypoints.
You can calculate distance, bearing, and steering to your
destination along either a great circle route or a rhumb line.
If your starting and ending points are under 100 nm apart, great
circle and rhumb line paths are practically the same.
1. At the NAVIGATION SETUP screen, press the CURSOR
PAD to highlight the DIST/BRG/STEER option, then press
the EDIT key.
Chapter 13 - Customizing Setup Functions
NOTE:
Page 13-23