How to use AdvCAT for air-to-air debris field analysis

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QuestionHow can you determine if debris will hit your aircraft?
If you have an aircraft in STK and are modeling an air-to-air defense scenario, you might be interested in knowing if - in the event of a successful intercept - your aircraft is still in danger because of the debris field.

If you have modeled your aircraft, threat, and intercept all in STK using Aviator and Aviator Pro, the debris field can be generated from statistical models using the STK Integration module to connect to an external script. Alternatively, STK's Missile Tool Kit (MTK), has a debris generator tool (introduced in version 11.2) that takes two STK objects and their intercept time and models the resulting debris field.

Regardless of the method that you used to generate the debris field, STK's Advanced Conjunction Analysis tool (AdvCAT) can be used to analyze the threat of a collision between your aircraft and one of the debris pieces in that field. The traditional applications for AdvCAT are satellite-to-satellite conjunction or launch window analysis; however, by changing a few of the default settings, AdvCAT works perfectly for low-altitude, short time-frame, air-to-air analysis as well.

Here are the steps to take:
  1. Insert a new object and select AdvCAT   
    1. If you don’t see the AdvCAT object in the menu, open the Edit Preferences dialog box and, on the New Object page, select it for display.
  2. In the AdvCAT object properties:
    1. Basic > Main:
      1. Set the threshold. This will be an ellipsoid to ellipsoid threshold unless the "Use Range Measurement" option is checked, in which case it becomes a center point to center point threshold. Any objects that get closer than this threshold will be considered a conjunction.  
      2. In the primary list, set your default tangential, cross track, and normal values and leave the class as Fixed. Next, add your aircraft ephemeris. It will inherit these default ellipsoid values, which is why you must set them before adding your primary object.
      3. In the secondary list, also set your default tangential, cross track, and normal values then add your debris object ephemerides. 
    2. Basic > Advanced
      1. Uncheck all of the Pre-filters. These are applicable for satellite-to-satellite situations, but not for this low to ground use-case.
      2. In the bottom left, check the box that says “Do not require ephemeris for entire analysis time period”.
    3. 3D Graphics > Attributes
      1. Check the boxes to Show everything and set the secondary ellipsoid option to "All". The default is "With Conjunctions", which means you would only see ellipsoids around debris objects that were determined to conjunct with your primary object.
  3. Compute your AdvCAT by either…
    1. Right-clicking on AdvCAT in the object browser, hovering over "AdvCAT", and selecting '"Compute".
    2. In the AdvCAT properties, under Basic > Main, click "Compute" in the top right of the window.
  4. Check for collisions by going to the report and graph manager for your AdvCAT object and producing one of the "Close Approach By…" installed report styles
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