Ambulance, fire, and police dispatch times compared with the atomic clock

To quantify any differences between the times used by public safety answering points (PSAPs) in a multijurisdictional county compared with the atomic clock and to determine whether there was consistency in any time differences.

All 25 ambulance, fire, and police PSAPs were contacted by telephone. The current time in hours, minutes, and seconds on the dispatch center's timepiece was requested. The atomic clock time was simultaneously recorded. Time differences between the reported and atomic clock times were calculated and the absolute values were used to calculate the mean difference. The procedure was repeated one week later. Consistency in time deviation was evaluated by subtracting the time differences between weeks 1 and 2 for each center.

All 25 centers were contacted and three declined to participate. Time differences ranged from -551 to 117 seconds (mean difference: 61.2 +/- 120.3) for week 1 and -103 to 79 seconds (mean difference: 36.9 +/- 33.4) for week 2. Time deviations between weeks 1 and 2 were: 0 seconds for one center, 1 to 30 seconds for 12 centers, 31 to 60 seconds for four centers, and more than 60 seconds for five centers.

The maximum time difference between dispatch center and atomic clock times was 551 seconds. This difference may be clinically significant for time-dependent research, quality improvement tasks, or medical legal reviews when multiple PSAPs are involved. Lack of consistency in time deviation over one week suggests systematic adjustment for these differences may not be possible.