SUMMARY In the solution of certain problems of aircraft and missile dynamics it is helpful and often necessary to use more than one system of axes and to do so requires that a number of geometric and kinematic relationships be established. This Item presents geometric relationships between the components of any vector in one orthogonal axis system and the components of the same vector in any other orthogonal system. Firstly the general relationship is given and then the particular forms this takes for body and earth axes (see Item No. 67003) and for the special axis systems (path axes) defined here are deduced. The angular velocity is sometimes represented in terms of the rate of change of attitude angles. Accordingly additional relationships between these non-orthogonal components and the more usual orthogonal set are given. Again a general relationship is given and particular forms are deduced.