Unit clear time

Unit clear time is the recorded point when a response resource is released from or completes an incident assignment under the local status system. It is usually a timestamp, not a duration. Its exact meaning depends on whether the source refers to leaving the scene, completing an assignment, or another defined milestone.

Read the status definition

“Clear” is an operational status word with different uses. A dataset should explain the event that triggers the timestamp and whether it belongs to one unit or the whole incident.

Historical NFIRS records, for example, defined a last-unit-cleared timestamp for the incident scene. That incident-level milestone differs from a complete timeline for each resource. NFIRS Basic Module time definitions.

Example

Hypothetical: Two units attend an incident. Unit A clears at 15:20, and Unit B clears at 15:45. A last-unit-cleared field records 15:45, while Unit A's own record retains its earlier time.

Using 15:45 for both units would overstate Unit A's assignment under this example's definition. The final incident timestamp cannot reveal every unit's duration unless their individual starting and ending events are also available.

Common confusion

A unit clearing a call is different from clearing a crime. Crime clearance is a separate reporting concept concerning the outcome of an investigation under applicable rules. An operational clear time says nothing by itself about arrest, prosecution, or conviction.

Clear time also should not automatically be treated as available time. Some systems use closely related statuses; others distinguish them. The source's dictionary must establish whether a resource was ready for another assignment at the recorded moment.

Administrative closure of an incident record is another possible event. A record can be updated after field activity has ended, so the time of the last database change should not be substituted for a resource's operational timestamp.

Calculating elapsed time

Subtract the appropriate start from the clear timestamp only after confirming both fields describe the same unit and compatible events. Include the calendar date for assignments crossing midnight.

State how reopened assignments, cancellations, and missing clear values are handled. If the source supplies only an incident's last clear time, label the result as an incident span rather than a sum of resource hours. That distinction keeps a simple timeline from becoming an unsupported workload estimate.

Related terms

• Unit available time
• On-scene time
• Unit status
• Clearance

Sources

• USFA: NFIRS Complete Reference Guide — Historical last-unit-cleared timestamp, page 3-33; used as a specific example rather than a universal CAD definition.