A more common convention in engineering application is as follows. In this the first rotation is taken around the vertical z-axis and gives the heading or yaw angle. The second is around a perpendicular axis fixed in the body and normal to the fixed axis. It is measured by the pitch or attitude angle. Finally, the third angle is one of rotation about the figure axis of thevehicle and is the roll or bank angle. This is known as xyz or Tait-Bryan convention. See the YAW, PITCH and ROLL motions in the following animation.