This is an on-screen charting gauge for finding your latitude/longitude from a sequence of two or preferably three sextant shots.
It is assumed the user is very familiar with the BB_Sextant gauge, and has the new 'BB_Sextant4.CAB' installed in their aircraft. If not, the accompanying Installation file should be read and followed first.
This gauge uses a BB_sextant gauge that has a different filename than the original. It is identical in operation with the original, but it has some added "hooks" so the gauge can share information with its new companion chart gauge. Although you cannot use the original BB_sextant.CAB, you can (and should) use the "_Sextant Manual" for the original sextant gauge. It can be found in the "Flight Simulator 9\Aircraft" folder.
1.Since this is only a "chart" manual, please use your normal procedure for preflight planning. Look at the picture below

Select the date, time, latitude, and longitude for the first position fix, and determine the elevations and azimuths to the three stars to be used to make the fix.
2. From pre-flight planning, or determination while in flight, when the time to make the fix approaches, enter the assumed latitude and longitude for the fix on the sextant workpad. For optimum results, the order in which the three stars is shot is important. First, the course line, next the check line, and finally, on the fix time, the speed line. This minimizes the error due to non-simultaneous shots. Said another way, the course line shot is of a star nearest the 3 or 9 o'clock direction (out the right or left cockpit window). The speed line is of a star near 12 o'clock, (or 6, if you have an astrodome). The check line is of a star near midway between the speed and course line directions. Usually you can start 5 minutes before hand and get the three one minute shots in. If you are running late, do the speed line on time, and the others later, but recognize that your position will be a few minutes "stale".
3. Look at the picture below


4. The plot is now finished, and after the sextant user records the fix position (latitude and longitude), the chart can be cleared and readied for the next set of shots by toggling "NM", the three "star" hot-buttons, and using the green arrows.
5. Although not elegant, the chart may also be used to plot a course to the fix, as follows:
a. Set the assumed position on the sextant worksheet (It may already be set there).
b. Move the green circle to the current fix position. Clicking on the NM letters in the bottom left corner makes visable now at the top of the chart the true reverse course and distance from the fix to the assumed position. (If it isn't appropriate to fly to that assumed position (e.g. if the course change would be more than 20°), crank in the next assumed position along the route into the sextant notepad, and fly toward it, using the reverse course and distance now showing at the top of the chart.
6. To prepare for the next fix, set the next assumed latitude and longitude in the sextant, and "zeroize" the position of the green circle.
Thank you for your interest in this gauge. For a detailed worked example flight, see the accompanying file Sextant Chart Example. Send comments/suggestions to bitzer7@comcast.net or MABeaumont@aol.com
Dave Bitzer
Mark Beaumont
March 2008