The second component of STK's Aviator capability is the procedure. The procedure is the action that the aircraft takes, at or relative to the site. Each procedure is described in its own Help topic in this section.
Standard procedures use a round earth model with gravity as a function of altitude. This model also includes Coriolis acceleration effects on the apparent accelerations required to fly the specified trajectory. Trajectories are constructed in the ECF frame, and the resulting body frame accelerations account for the higher fidelity models.
Methodology Between Procedures
The methodology of the Enroute procedure is the default methodology used by Aviator when calculating a route between procedures, such as traveling from the end of the previous procedure to the beginning of a holding pattern.
Invalid Procedures
Aviator validates all procedures in a mission to ensure that it is physically possible to perform them in relation to one another. If you create a procedure or modify a performance model such that it invalidates the mission, a warning message will appear on the screen, and the invalid procedure and each of the procedures after it will be highlighted in red.
Point to Point procedures (Basic Point to Point, Enroute, and Terrain Following) have a greater co-dependency than other procedures that is worth noting. It is necessary for each point to point procedure to know something about the start of the next procedure, and this requires that a sequence of point to point procedures be calculated as one "super procedure". This in turn requires that all point to point procedures in the sequence be properly configured, because a single invalid procedure will cause all of the procedures in the sequence to become invalid. In particular, for Terrain Following procedures it is important to consider that when a sequence of Terrain Following procedures spans two or more mission phases, the Terrain Follow performance model must be selected for all phases or you will invalidate the entire sequence of Terrain Following procedures across all phases.
If your mission becomes invalidated, you will need to edit one or more procedures or performance models to reestablish the mission's validity. The Message Viewer will display more information about the specific nature of the invalidation. When troubleshooting invalid procedures, always pay close attention to the last procedure or phase you modified - don't immediately assume the first invalid procedure, sequentially, is where the problem lies.