This paper presents a unique derivation of airborne trajectory analysis equations from the classical physics equations of uniformly accelerated motion. These trajectory analysis equations are applied to an example problem with realistic real world values. A current widely utilized equation of human trajectory analysis ignores an important cosine function in the calculation of horizontal launch velocity. It is shown that ignoring this cosine function can yield significant error in calculations.A graph is derived from published data on freefall sky diving. This graph can be referenced to adjust calculated velocities for the effects of air drag. It is shown that prior published data which has been widely utilized within the accident reconstruction profession, is inaccurate.A simple method for the application of the derived equation and data to real world problems is outlined. The method illustrates that even when the angle of launch and first point of contact with the ground are unknown, good results for launch velocity can be obtained.