DEVELOPMENT OF FAST-TIME SIMULATION TECHNIQUES(27)

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The Sensor agent is assumed to detect only moderate and severe CAT events and to not have the ability to distinguish between those two severity levels.  For this demonstration, a detection rate of 100 percent and a false alarm rate of zero percent are assumed.  The lookahead time varies in the three sensor cases simulated:  30 seconds, two minutes, and five minutes.  The lookahead time is fixed and nonrandom in all replications of a case.  When a moderate or severe CAT is detected by the Sensor, the Sensor issues an alert to the Flight Crew.  Although there is continual probing and alerting as the Aircraft closes on the CAT, for purposes of this demonstration, only the first alert, issued at the lookahead time, is acted upon by the Flight Crew.  Later versions of the model can elaborate on flight crew responses to other detection and false alarm rates and alert modes.
In the RFS implementation of this scenario, weather is represented by an object called AtmosphericModel.  For this demonstration model, we created an agent (called Wx_Model), which inherits properties from AtmosphericModel and, in addition, handles all turbulence events as independent instances of this class.  It stores an array of turbulence events, each uniquely identified by the following properties: 
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure IV-2  Flight Crew - Controller Vocabulary
 
 

Intensity  {LIGHT, MODERATE, SEVERE, EXTREME}

Boundary data file name

Turbulence type  {CHOP, EXTENDED}

Duration type  {OCCASIONAL, INTERMITTENT, CONTINUOUS}.

In addition to these characteristics, start time and duration are required parameters of each turbulence object.
It is important to note that, even if two turbulence events have the same intensity, type, and duration type, and identical points are identified as boundary points, as long as these attributes are stored in different files, they are treated as different turbulence events.  On the other hand, one data file can serve more than one turbulence event.  If at any time in the simulation a new turbulence object appears using the same boundary data file as an already existing one, then the existing turbulence event will cease to exist at that moment and will be replaced by that new turbulence object.
Presently, the program accommodates only a single turbulence area shape – a quadrangular prism – or anything that has six faces with four lines defining each face.  The program can be generalized in the future to handle other shapes.
Due to RFS design rules, modules of the type used for weather cannot determine on their own when to update.  They need a reminder object, i.e., one of a different type that will change at the same time as the weather object should be updated.  In our simulation, an object called Skywatch has been created that updates the weather objects (turbulence events) by determining its own next update times to match the required start or end times for the next turbulence to be updated (i.e., turned ON or OFF).  This approach ensures that even if there are no aircraft coming into the simulation before the first turbulence appears, the latter will appear on time.
A sensor agent (Sensor) is linked uniquely and permanently with each AircraftOnRoute in the same sense as RFSPilot.  It exists only as part of its aircraft.  Its parameters, set by RandomACGen (see above), include the following:
Sensor probability of detecting the CAT correctly – confidence level

False alarm rate (percent of detections that are false)
　
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