# True Course 10 Degree Tables

# International Operations Appendices

Back in the old days if you were presented with a reroute when oceanic, you pulled out the charts and plotter and got to work building a new flight plan. If you were good, you could churn out three thousand miles of master document in about fifteen minutes. If you were really good, you had a book of ten degree tables and could cut that time in half.

These days I would just call in the change to my flight planning service and have them fax, e-mail, or just read them to me over the phone. What if you don't have that kind of connectivity or if you just want to be old school for a day?

### Purpose

If required to fly an unplanned oceanic flight plan — you got a reroute just prior to coast out — you need to build a new master document with courses and distances between waypoints so you can still make all the necessary checks before each point and also so you can make your post position plot. The 10 degree tables below provide your true courses and distances between any two positions expressed as latitudes (to the nearest degree) and the next position expressed as a longitude 10 degrees east or west.

For example, say you are 50°N 030°W heading to Europe and your next position will be at 51°N 020°W. You could pull out a plotter and come up with a course, add the variation, and end up with the correct true course. Then you could measure the distance, compare that to the nearest line of longitude and come up with a distance. You would probably do this a few times to make sure you didn't make a mistake, either with the plotter or your ad hoc measuring device. Or you could go to the From 50° Latitude table, check the course provided on the 51° row and Northern Hemisphere / East column and see your true course will be 081° and reading across see that the distance between these two points is 386 nautical miles.

### Initial versus Midpoint Courses

Figure: True Course initial vs. midpoint vs. ending, from Eddie's notes.

The 10 degree tables provide the course at the midpoint between two positions. This will agree with your plotter if you put the center of the compass over the midpoint.

Most FMS (and many flight plans) print the initial course leaving the waypoint. The difference can be significant. When checking your progress, make sure you understand what the FMS is telling your, what you are seeing on the 10 degree table, and what you see with a plotter on a chart.

More about this: Initial vs. Midpoint Course.

### From 00° Latitude

To determine the average true course and distance between two points which are ten degrees apart in longitude:

- Find the table with the starting latitude (North or South doesn't matter)
- Find the corresponding latitude in the second column. (If there are two choices, the latitude on top is in the same hemisphere (North or South)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 01° Latitude

To determine the average true course and distance between two points which are ten degrees apart in longitude:

- Find the table with the starting latitude (North or South doesn't matter)
- Find the corresponding latitude in the second column. (If there are two choices, the latitude on top is in the same hemisphere (North or South)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 02° Latitude

To determine the average true course and distance between two points which are ten degrees apart in longitude:

- Find the table with the starting latitude (North or South doesn't matter)
- Find the corresponding latitude in the second column. (If there are two choices, the latitude on top is in the same hemisphere (North or South)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 03° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 04° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 05° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 06° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 07° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 08° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 09° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 10° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 11° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 12° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 13° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 14° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 15° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 16° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 17° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 18° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 19° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 20° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 21° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 22° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 23° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 24° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 25° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 26° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 27° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 28° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 29° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 30° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 31° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 32° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 33° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 34° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 35° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 36° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 37° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 38° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 39° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 40° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 41° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 42° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 43° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 44° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 45° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 46° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 47° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 48° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 49° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 50° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 51° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 52° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 53° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 54° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 55° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 56° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 57° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 58° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 59° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 60° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 61° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 62° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 63° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 64° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### From 65° Latitude

- Find the table with the starting latitude (North or South doesn't matter)
- Read the true course underneath the desired hemisphere and direction of travel (east or west)
- Read the distance in the last column

### Book Notes

Portions of this page can be found in the book International Flight Operations Manual, Part VIII, Chapter 37.