What is meaning of Great Circle Sailing ?

Find Dist:

COS AB = (COS PA X COS PB) + (SIN PA X SIN PB X COS P)

Find Initial Course:

                ( COS PB – COS AB X COS PA)
COS A = ———————————–
                             (  SIN AB X SIN PA)

Find Final Course:

                ( COS PA – COS AB) X ( COS PB)
COS B = ————————————–
                          (SIN AB X SIN PB)

The initial course always has same name as the initial latitude and east or west direction of the course. The final course always has the opposite name from final latitude unless initial position and final position are in different hemispheres, when the final will have same name as final latitude and east or west direction of the course.