In my experience, they are never dispatched to GPS coordinates. The PSAP gets the coordinates automatically pulled up in their mapping system showing the closest address. The only time I've ever exchanged raw GPS coordinates was in ~2003 when the Garmin was out of batteries, and the spare was missing from a rescue vehicle and we were trying to tell a helicopter where we were. I had 1/16th of a bar of service and managed to hit the neighboring 911 center. I asked them for my coordinates. They had to go to some special screen to give them to me, and then I relayed them to Life Flight. They were off by about 500 feet, but there was only one clearing in a sea of trees, and we had flares. -A On Mon, Sep 27, 2021 at 2:18 PM Jay Hennigan via VoiceOps < voiceops at voiceops.org> wrote:
On 9/27/21 13:34, Mark Lindsey via VoiceOps wrote:
In the top 25 cellular market areas, nationwide cell phone providers are already required to provide Z-axis (elevation) data within 3 meters for 80% of calls [for compatible devices]. The requirements increase each year; by 2026, /all/ cellular providers are required to provide z-axis precision for dispatchable location of +/- 3 meters everywhere in the US.
This is all in addition to providing +/- 50 meter horizontal (x, y axis, also known as latitude and longitude) precision for 911 calls.
Interesting as elevation accuracy for GPS is worse than lat/long.
So when first responders get dispatched to 34.2270545 degrees north, 117.6422397 degrees west, 538 meters AMSL, where do they go? (I just randomly typed those numbers so if it's under a mountain don't blame me.)
Considering just the x/y axis, determining the right room or suite in a large single-story office building, factory or warehouse is going to be a challenge. In a huge multi-story high-rise with poor to no internal GPS reception it's going to be nearly impossible. Especially if it's in the middle of a bunch of other high-rise buildings with corresponding multipath and reflections.
-- Jay Hennigan - jay at west.net Network Engineering - CCIE #7880 503 897-8550 - WB6RDV _______________________________________________ VoiceOps mailing list VoiceOps at voiceops.org https://puck.nether.net/mailman/listinfo/voiceops