FindMeSAR - For anyone calling 911 with a cell phone

[Joseph Elfelt]

FindMeSAR (http://findmesar.com) is a ‘no cost’ public service browser app that is intended to be very basic. Many of you that read this forum will have no use for this app since your phone already has a full featured navigation app that can display your coordinates. But this very basic app might be useful for people you know who are clueless about coordinates.

Caution! You should never rely on an app that displays coordinates but does *not* display the related accuracy value. How do you know the accuracy is not 1,000 meters or more?

I developed this app after learning a great deal about what happens when a cell phone calls 911. Here is the short version. Within 30 seconds the carrier handling the call (might be *any* carrier) is supposed to make reasonably good “Phase 2” coordinates available to the dispatcher. Sometimes that technology simply does not work for various reasons. The FCC regulations also allow large exemptions from the “Phase 2” requirement.

If the dispatcher does not have “Phase 2” coordinates then they will still have “Phase 1” coordinates. Unfortunately the “Phase 1” coordinates are for the cell tower that is handling the 911 call and the caller can easily be several miles away.

And of course if someone with a cell phone calling 911 can adequately describe their location by giving a street address or by other means, then coordinates are not really needed. But it is easy to think of situations where the caller is not going to be able to describe their location specifically enough in order to minimize response time.

My conclusion is that anyone who calls 911 with a cellphone from *anywhere* (backcountry or frontcountry) should have a way to provide accurate coordinates to 911 just in case (1) the carrier does not provide “Phase 2” coordinates that have good accuracy and (2) it is not possible to give a specific verbal description of the location. I developed FindMeSAR as a backup plan to meet that need.

Sometimes the 911 dispatcher might have “Phase II” coordinates but they have a large “uncertainty” (i.e. accuracy) value. If the “uncertainty” value on the 911 screen is 1,000 meters then you need to know that because you can probably provide coordinates with an accuracy value of less than 10 meters. If you ever have to call 911 you should speak their language and ask: “Do you have Phase 2 coordinates and what is their uncertainty value?”

Note that if the call is not exempt from the “Phase 2” requirements, then per FCC regulations the carrier handling the call has 30 seconds from when the call starts to make reasonably good coordinates available to the dispatcher. In many call centers the dispatchers have to ask (“re-bid”) to have the “Phase 2” coordinates updated on their screen.

FindMeSAR is intended for smartphones. It will also work well on tablets that have a GPS chip. It includes an icon that you can save on your home screen. Or you could save a bookmark in your browser. Yes, you can open the app with the browser on desktops/laptops but the results are unpredictable.

The "Next Format" button will loop through four different colored screens. Each screen shows your location using a different coordinate format. Most 911 call centers likely use latitude longitude expressed as decimal degrees (yellow screen).

Each screen displays (1) your coordinates, (2) an accuracy value and (3) a timestamp. FindMeSAR will continue to update your location. Typically if you are outside your location will be fixed to less than 10 meters in well under a minute. If you give this information to 911, then give all 3 pieces. The timestamp tells responders this is your current location and not any kind of cached (i.e. old) coordinates from earlier in the day.

If your browser is online then the “Display map” button will open Gmap4 (I am the developer) and show your location on the Google aerial. The circle on the map was drawn using the accuracy value as the radius. There is supposed to be a 95% likelihood that you are inside that circle.

FindMeSAR gets your location from your browser. Your browser gets your location from your phone’s location services which may include GPS, cell towers, wi-fi, etc. You can test the accuracy of your phone’s location services simply by standing someplace that you can see on the Google aerial, running FindMeSAR, turning on the map and seeing if the circle includes your location.

Android users: If you go to location services in your setup, then you can pick from:
1. High accuracy (uses GPS, cell tower, wi-fi, etc)
2. Power saving (ignores your GPS!)
3. GPS only (also called Device only)
I recommend #3 since there are multiple reports that #1 is less accurate. YMMV.

For the most accurate coordinates you should be outside with a reasonably good view of the sky. If you are inside you could stand by a window. In a car you could place your phone under the windshield.

Documentation is also online at:
http://findmesar.com/p/911-wireless-loc ... uracy.html

FindMeSAR works online and offline. For more information on offline use please see the additional documentation link just above and click "Read FindMeSAR part 3". That webpage also has other useful information.

Finally, if you think this post is particularly useful and would like an easy way to tell others, feel welcome to share the April 15, 2016 post I made on the Gmap4 facebook page.
https://www.facebook.com/Gmap4/

[forestkeeper]

Does this work in all lower 48 states? Hiking/photographing solo in Yosemite and the Olympic National Parks during the last two weeks of May.

[Joseph Elfelt]

Works worldwide.
Just like a GPS (Garmin, etc)

But note that the newest version of Chrome (v50) does not support browser geolocation for HTTP websites. For that reason I am in the process of converting my websites to HTTPS. Hopefully I will be able to complete that task in the next few days.