What time did the 911 call come in? Attorneys and legal nurse consultants investigating the details of an incident may find this detail crucial. There are two main sources of keeping accurate time.

The U. S. Naval Observatory maintains the Official U.S. Time for the Department of Defense and for Global Positioning Systems (GPS). This agency performs this function through a series of atomic time clocks synchronized within 10-nanoseconds. Most state police, air medical units, and cell phone services use the Official U.S. Time for their recordkeeping.

Greenwich Mean Time (GMT) sets the time of day. GMT is the mean (average) time that the earth takes to rotate from noon-to-noon.

GMT is international time and the basis for world time zones. The atomic time clock is adjusted by leap seconds to maintain synchronicity with GMT (Greenwich Mean Time, 2009). Agencies that do not use the Official U.S. Time use GMT.

Upon reviewing recorded 911 calls and records, the attorney or LNC will observe that some dispatchers verbalize the time of day. Dispatchers are trained to include verbal time, using military time as part of their conclusion to a statement; however, many do not. When dispatchers do provide a time they tend to use whatever clock means they have available, (e.g., a digital watch, a wall clock, an electronic clock) which invites the question as to how the clocks are synchronized.

Some dispatchers do not verbalize the time, but instead rely on the PSAP to imprint an electronic time stamp on the recording. This method of documentation can have its own flaws.

When the PSAP is activated from the 911 caller, an internal log that can be printed out is maintained which uses the Official U.S. Time. However, if the dispatcher types in a text note, the PSAP will not capture the Official U.S. Time until the dispatcher touches the “Enter/ Return” key.

At that moment, the Official U.S. Time is electronically imprinted onto the recording. The flaw occurs when the dispatcher becomes busy and is unable to touch the Enter/Return key, over a period of time, which keeps the clock ticking.

It is not uncommon to see a 5–10-minute discrepancy when reviewing PSAP records. Telephone records, including cell phones, text messages, and landlines, use the Official U.S. Time, sometimes rounded up to the next minute. The attorney will need to contact the telephone provider for the precise methodology used as illustrated on the itemized telephone bills.

Regardless of the time variables identified, specific questions must be asked and answered to assist the attorney or LNC in determining the timeline of the events:

• How is the time determined? (clock, watch)
• How accurate is the time?
• Are the clocks synchronized? How often?
• Is there supporting documentation maintained to determine when the clocks were last synchronized?
• When was this performed? Who performed that task?
• What reference source is used to synchronize clocks (Official U.S. Time or GMT)?

Modified from Enhance your Investigations Using Technology, The Journal of Legal Nurse Consulting, Fall 2011

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