All dates and times are entered as numerals. For time of day, the 24-hour clock is used, where midnight is expressed as 00:00. Many automated systems provide times formatted in hours, minutes and seconds, such as 12:34:56. The collection of seconds is optional and not required; however, NFIRS supports the collection of times in this format.
The Alarm Date and Time is not the time that the Public Service Communications Center received a call from the public.
Alarm Date and Time is important for three reasons:
As a legal requirement for recording the precise time that notification was made of the incident.
As information for determining the frequency of particular types of incidents by time period.
As the starting time to determine the length of time taken to arrive at an incident and the total amount of time spent on the incident scene.
Last Unit Cleared Date and Time is the actual month, day, year and time of day when the last unit cleared the incident scene.Last Unit Cleared Date and Time does not reflect an “in service” time, nor does it include the time spent transporting a patient to a hospital facility or transit back to the station.An Arrival Date and Time is not required for calls where the fire department was cancelled prior to arrival, since no units from the department arrived on the scene of the reported incident.The times entered on the Apparatus Module should be unit specific.See More here.... https://www.usfa.fema.gov/data/nfirs/support/nfirsgrams/nfirsgram_dates_times.html