Computer Aided Dispatch Systems

The ComputerAidedDispatch, or CAD, system is the nexus of the emergency dispatch process. Calls for emergency services are received by a 911 call taker and keyed into the CAD system. The CAD routes the entry to the appropriate radio dispatch position(s) so that first responders can be dispatched to the scene of the emergency. At the radio dispatch positions the CAD system makes recommendations to the radio operator concerning a suggested response after checking the availability of public safety personnel. Information about personnel responding to the scene of an emergency is maintained in the CAD including an electronic time-stamp reflecting the time the call was received, dispatched, when each unit arrived on the scene, and the time that the unit became available again.

The CAD system interfaces to national, state, and local law enforcement databases that are important to field personnel. The following databases are included in the CAD system:

• Virginia Criminal Information Network (VCIN)
• National Crime Information Center (NCIC)
• Division of Motor Vehicles (DMV)
• National Law Enforcement Telecommunications System (NLETS)

Additionally, the CAD system is the host for all public safety mobile data computers (MDCs). Mobile data computers are discussed as a separate topic.

The technology exists today that allows the customization of CAD systems to include advanced features important to public safety first responders. The most important features include:

• Automatic Vehicle Locator (AVL) - technology exists today that allows an AVL system to interface with a CAD system that supports AVL technology. AVL allows the CAD system or communications officer to select the closest unit(s) for a high priority call. The use of AVL technology has been proven to reduce response times to calls for service and increase the likelihood of apprehension of a suspect. Increases in apprehension rates help to reduce crime overall.

• Premise History – communications officers and all first responders, especially police officers, need to know the premise history associated with addresses to which calls are dispatched. The history includes calls for service for the past 24-hours and the past 30 days or more.

• Cautionary Flags – in addition to call history, cautionary flags can be established for the premise that includes information related to officer safety and the safety of other emergency personnel. For example, addresses associated with violence, aggressive animals, or other dangers can be flagged so that the responder is aware of potential threats prior to their arrival on the scene.

• Medical Flags – these flags make first responders aware of any persons residing at the premise who have requested a medical flag because of a medical condition or alerts them about residents who may be physically or mentally challenged.

There are additional functions commonly available in modern CAD systems that are considered essential to public safety operations and the operation of a modern 911 center. They are summarized below:

• Records Management System (RMS) Interface – the CAD system should interface with the records management system. Crime analysis and trend mapping begins and ends with the records management and computer aided dispatch systems. Timely and accurate data is essential to the development and organization of all directed patrol initiatives and crime reduction efforts.

• GIS Technology – an important feature of the CAD system is its integration with GIS tools. GIS tools can be used to dynamically and seamlessly redraw police beats and sectors and fire dispatch zones. This is an important attribute that drastically reduces the amount of time needed by information technology support services to incorporate geographical changes.

• CAD-to-CAD Interface – present day technology supports CAD to CAD interface with other jurisdictions. This technology enables one CAD system to share information with CAD systems in other jurisdictions. This regional sharing of data has important implications for interoperability and is critical to support the transfer of timely and accurate data across jurisdictional lines.

• Duplicate Call Detection – this feature is especially important during critical incidents that generate multiple calls from the public including natural disasters such as hurricanes or other hectic events such as a multiple alarm fire. During hyperactive events calls for service are entered into the CAD at the rate of hundreds, or even thousands, per hour. The duplicate call detection feature enables the CAD to monitor the system for duplicate calls and eliminates them to prevent the system from reaching maximum capacity. Without this automated feature, a communications officer would need to monitor the system and manually eliminate duplicate calls. Access to this feature frees essential personnel to engage in other activities important to the success of the mission at hand.