Report: Cellular E911 location information inconsistent
ORLANDO—Public-safety answering point (PSAP) managers should work with cellular providers in an effort to improve the location data the carriers provide when their customers make emergency calls, Association of Public-Safety Communications Officials (APCO) representatives said during the APCO Winter Summit yesterday.
This recommendation coincided with a summary report about Project LOCATE, APCO’s study of location data from cellular carriers that was funded with a $750,000 grant from the Public Safety Foundation of America. Provided in detail to APCO board members this week, an overview of the report was the subject of a session yesterday afternoon led by Nancy Pollock, chairperson for Project LOCATE.
Conducting the tests—seven PSAPs across the nation receiving 203 calls per carrier in their territory—was an eye-opening experience for APCO, which learned a great deal about the factors that can generate a wide variance in the accuracy of wireless E911 location data, Pollock said.
“The carriers can do a very good job of providing location information—it depends on the conditions and a whole litany of variables,” she said. “For me, the disappointing piece of that is that it wasn’t always consistently provided. That’s the thing we have to learn to deal with and try to understand what conditions [get it] into that inconsistent area.”
Factors that can impact the accuracy of the location data include the type of handset, the type of network, tower density and PSAP rebid timing, Pollock said.
For a dispatcher, that inconsistency can be problematic, because inaccurate E911 location information can result in deployment of personnel and equipment to a site where there’s no emergency, said Bill Cade, APCO’s subject-matter expert on E911. To help address this situation, Cade recommends that PSAPs conduct their own low-cost testing programs to identify trends in the accuracy of the location data from various locations.
“What you don’t know is the value of that location information, unless you do performance testing,” he said. “If I have done performance testing, and I know that calls in this general area were normally not more than several hundred meters off, that’s helpful to me—it gives me a smaller circle to send [responders] to.”
Although the entire report was not shared with attendees, several examples cited showed that the carriers did not meet FCC accuracy guidelines during the tests. However, Pollock emphasized that the FCC guidelines let carriers average data from all areas of the nation—typically, location data is more precise in urban areas that have greater tower density—and that Project LOCATE was not designed to be a compliance test.
“We’re not going to indicate that Verizon did this and Sprint did this—that’s not our purpose,” she said. “Our purpose is to help the PSAPs understand that there can be differences in [cellular location accuracy] … to help them make good dispatching decisions.”
Pollock acknowledged that the Project LOCATE team members were apprehensive about working with the cellular carriers, who could have perceived the study as a threat. But such concerns were quickly dismissed, as the carrier representatives cooperated with the project in an exemplary manner, Pollock noted several times.
“One of the things that we have learned is that working with the carriers is better than not working with the carriers,” she said. “Forging that partnership is important. The improvement of service is possible, and we’ve certainly been able to demonstrate that in some of the test areas.”
To facilitate such relationships, PSAP managers should appoint a lead contact within their organization to serve as a liaison with the cellular carriers in the area, Cade said.
