The STK's
Advanced Conjunction Analysis Tool (
AdvCAT) capability has traditionally been used for space-based conjunction assessment. However, you can also use it to determine close approaches of
any objects in STK, making it perfectly suited for air traffic management applications. With just a few adjustments to the default settings, you can use
AdvCAT and STK to determine if planned aircraft routes are too close and if collisions might occur. This capability is particularly relevant considering the growing popularity of unmanned vehicles. Watch this video to learn how to start using
AdvCAT in your air traffic simulations.
See FAA CAT from AGI Engineering on Vimeo.
Here are the steps to take in a scenario that already has aircraft objects built and propagated:
- From the Insert menu, select New... and select AdvCAT. If you don’t see the AdvCAT object in the menu, click the Edit Preferences button and, on the New Object page, select the Show check box next to AdvCAT and click OK.
- In the AdvCAT object properties:
- Basic > Main:
- Set the threshold. This will be an ellipsoid-to-ellipsoid threshold, unless you select the "Use Range Measurement" check box, in which case it becomes a center-point-to-center-point threshold. When any objects that get closer than this threshold, STK will consider the event a conjunction.
- In the Primary List, set your default Tangential, CrossTrack, and Normal values and leave the Class value as "Fixed." Next, add your aircraft ephemeris from the Available list to the Chosen list. It will inherit these default ellipsoid values, which is why you must set them before adding your primary object.
- In the secondary list, also set your default Tangential, CrossTrack, and Normal values. Then add your debris object ephemerides.
- Basic > Advanced
- Clear all of the Pre-Filters check boxes. These are applicable for satellite-to-satellite situations, but not for this low-to-ground use case.
- In the bottom left, select the check box that says, “Do not require ephemeris for entire analysis time period”.
- 3D Graphics > Attributes
Select the Show check 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 STK determined would have a conjunction with your primary object.
- Compute your AdvCAT using one of the following methods:
- Right-click AdvCAT in the Object Browser, select "AdvCAT", and select '"Compute".
- In the AdvCAT properties, under Basic > Main, click "Compute" in the top right of the window.
- Check for collisions. Right-click your AdvCAT object, select Report & Graph Manager, and generate one of the "Close Approach By…" installed report styles.
If you have an aircraft in STK and are modeling an air-to-air defense scenario, another application of
AdvCAT you might be interested in is 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, you can generate the debris field from statistical models using the
STK Integration capability to connect to an external script. Alternatively, if you have access to STK's
Missile Tool Kit (MTK) capability, it has a debris generator tool that takes two STK objects and their intercept time and models the resulting debris field. Then you can use the same process as demonstrated above to assess the scenario for possible conjunctions between your aircraft and falling debris.
Note: MTK is export controlled and is therefore not available to all users of STK.
