The difficulties of wireless calls
Wireless calls have profoundly changed the 911 sector’s landscape. In the beginning, there were addresses associated with landline devices. These addresses weren’t perfect but they were specific. In contrast, location information from wireless devices—referenced by latitude and longitude—often is lacking. Indeed, the emergence of wireless technology has challenged PSAPs in numerous ways and the debate over wireless location accuracy has ensued for years. The fact remains that today more than 80% of 911 calls in our area come from wireless devices, and that number continues to grow.
The original scenario for wireless 911 involved calls that were made outdoors and usually from a moving vehicle. Currently the demographics are shifting toward indoor calls made from homes and businesses, as more and more citizens are giving up their landline phones and becoming wireless-only households. New technology becoming available may boost that shift considerably. That is a significant change for PSAPS trying to locate wireless callers.
The next shift in demographics no doubt will be related to new devices from which 911 can be accessed. Each step in this wireless development curve means PSAPs have to assess, adjust and compensate. Even with advanced tools and supplemental information, the fact remains that wireless calls take more time and introduce more risk. PSAPs have to compensate with staffing, procedures and budgets. Emergency response requires a location and when that location comes from a wireless device, how close is close enough?
Figure 1 depicts an image of a residential neighborhood. The larger circle has a radius of about 100 meters. The smaller circle has a radius of about 50 meters. A few meters one way or the other in areas like this makes a big difference in the ability to locate a caller inside a residence who can’t verbally provide a location.
FIGURE 1
While new opportunities exist for supplemental information, locating a caller inside a building still is not an exact science. Tighter accuracy certainly enhances and expedites the process. Devices we’ve tested recently deliver accuracy in the 6-10 meter range. Figure 2 below displays a circle with a radius of about 6 meters over a parking facility. It’s easy to imagine how this would impact the time required to find a caller.
FIGURE 2
Meanwhile, Figure 3 below depicts the same parking facility, indicating multiple floors below the upper level. Currently, there is no effective way to pinpoint wireless 911 calls along the “Z” or vertical axis, which is a limitation that vexes PSAP managers. While we can locate a vehicle in this facility based on longitude and latitude, we have no way of knowing what floor the vehicle is on. That adds precious time to emergency response.
FIGURE 3