In long and fairly complex reports and articles, especially theoretical and experimental reports where the purpose of the document is to apply, verify, or illustrate one or more theories, include a separate section presenting relevant theoretical formulae and the techniques by which any experimental results are predicted. When introducing equations, be sure to define all symbols used in them.
Attitude Display ImplementationThe graphics display created for this experiment presented attitude information to the pilot in the HMD [helmet-mounted display]. For the purpose of the experiment, no other information (e.g., airspeed, altitude) was presented during the actual data collection. The attitude display consisted of a pitch ladder, velocity vector symbol, and waterline symbol (fig. 3).
With the conformal attitude presentation, the appearance of the displayed information was dependent on the head position of the pilot. The displayed horizon line of the attitude symbology, if it was in view, would always overlay the horizon of the outside scene. If the line of sight of the pilot was not aligned with the body axis of the airplane, the attitude of the airplane . . . could not always be easily obtained from the displayed symbology.
With the body-axis concept, no matter which direction the pilot moved his head, the display appeared as if the pilot was looking directly out the front of the airplane. In essence, the body-axis concept was analogous to physically mounting a HUD [head-up display] to the helmet. With this concept, the pilot could always directly determine the attitude of the airplane. However, in situations where the line of sight of the pilot was not aligned with the body axis of the airplane, the displayed horizon line of the attitude symbology, if it was in view, would not overlay the horizon of the outside scene.
--D. Jones et al., "Concepts for Conformal and Body-Axis Attitude Information for Spatial Awareness Presented in a Helmet-Mounted Display," National Aeronautics and Space Administration