An orthodrome is a track corresponding to a great circle segment. The plane defined by an orthodrome passes through the center point of the sphere dividing it into two equal halves.
Orthodromes provide for the smallest distance between two locations on a spheroid. However, navigating along a great circle implies, in general, changing the bearing constantly. The exceptions include flying along the equator or along a meridian.
The mobile application allows you to determine the (true) bearings - initial and final - and the distance of an orthodrome defined by two positions; given their respective geographic coordinates (Lat/Long). Have fun!