Wireless 911 call location data not always accurate

More than 215,000 emergency calls were made to the Kern County communications center in 2016. Out of those, 89 percent were made from cellphones.

How do dispatchers know where those 911 calls are coming from? It’s complicated.

Tami Kimbrell, a senior dispatcher and 911 coordinator at the Kern County communication center says, “I don’t know where to send help unless they tell me, and I’m not always going to know where they're at 100 percent.”

That’s not to say they don’t get any information regarding a caller’s location. It's just not as accurate as you might think.

Dispatchers receive two phases of information. The first "phase" is the location of the cell tower that routes the call. This will get a call routed to a nearby dispatch center, though not always one in the correct jurisdiction.

Even when it does get to the right center, it’s not specific enough to allow dispatchers to accurately send resources.

The second phase of information is more specific and usually includes an approximate address, as well as two numbers, a distance and a percentage.

For example, Eyewitness News was allowed to do a test call from within the facility. The system was 90 percent certain we were within an 11 meter radius of the address it provided. While the address was off by a few numbers, our crew was within the 11 meter radius.

Kimbrell says that’s “pretty good” for the system. The only thing that is better is a verbal description of the location from the caller. But in emergency situations, that isn’t always an option.

“I would say the most difficult time we have is usually with the rescue calls,” says Kimbrell. “If they're up in a lake area or mountain area, those are giving huge ranges and percentiles, so it’s not really accurate."

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