Computer-aided dispatch

Computer-aided dispatch, or CAD, is software that helps public-safety staff record requests, assign responders, and track incident and unit activity. A CAD record captures information used to coordinate a response. It can contain preliminary reports and changing classifications rather than established findings about what happened.

A record of the response as it develops

Call takers enter information such as the reported location, the reason for the request, and its urgency. Dispatchers use that information to coordinate available units. As responders acknowledge assignments, begin traveling, arrive, or finish, the system can record those changes.

The Bureau of Justice Assistance describes CAD as supporting call handling and prioritization, with possible connections to other systems. Its glossary is a legacy reference: it explains the basic role, but does not establish the features of a particular modern installation. BJA glossary.

A public CAD extract usually presents only selected fields from that operational record. It may show one classification and a few timestamps without the earlier versions, notes, or unit history that explain them. A neat row in a download should not be mistaken for the complete record.

Example

Hypothetical example: At 2:05 p.m., a caller reports a vehicle blocking a driveway. A call taker creates CAD event C-204 and records the location and complaint. At 2:12, a dispatcher assigns a unit. The officer arrives at 2:18, finds the owner nearby, and records that the vehicle was moved. The call closes at 2:26.

This sequence explains the handling of a service request. It does not necessarily produce an arrest or a separate written offense report. If a report is required, it might receive a different case number in the records management system.

The timestamps also answer different questions. Seven minutes elapsed between creation and assignment, while six elapsed between assignment and arrival. Neither interval should be called the department's “response time” without checking its chosen starting and ending events.

Common confusion

CAD and a records management system have different jobs. CAD supports coordination of work in progress. A records management system stores and manages reports and related case information. Systems can exchange information, but their records do not necessarily match one for one.

A CAD number and a case number are not automatically the same identifier. A source may use “incident number” for either. Join two files only when the agency documents the relationship; matching a date and street is not a reliable substitute.

Operational updates and public updates are separate. Staff may update CAD during a response while the public file appears later or omits the event. “Computer-aided” does not mean that the public is seeing a live feed.

Why classifications can change

San Francisco documents an original call type, a final call type, and a disposition, or handling outcome. New information can change the category during a response. Its explainer also warns that operational dispositions should not be used as official arrest statistics. San Francisco CAD explanation.

When reading a CAD-derived map, look for the agency's field dictionary, extraction schedule, and inclusion rules. Identify whether each row describes an incident or a unit assignment. Then read the category as a description of the dispatch record at the stated stage, with later investigative findings kept separate.

Related terms

• Call for service
• Records management system
• Call number
• Unit status

Sources

• Bureau of Justice Assistance — Glossary of Terms, CAD and RMS entries. Supports the systems’ core functions; legacy implementation details are not adopted.
• City and County of San Francisco — Law Enforcement Dispatched Calls for Service, revised September 10, 2021. Explains dispatch workflow, identifiers, classifications, and disposition limitations.