Spot 911 Activation Navigation Homework Assignment

Here's a real-world navigation challenge for you to consider and work through.

We had a very small call-out this evening (2009-04-19) in response to a Spot 911 activation in Teller County.  The subject activated his Spot's 911 feature in the general area of Signal Butte along Trailcreek Road (Teller County 3).  Mike Smith (#54) was activated as the IC, and Ray Bernhardt (#84), Mike Symes (#128), and Don Johnson (#106) were called out to get to the subject using the snowcat.

A sheriff's deputy reached and extracted the subject while we were still hooking up the snowcat.  We received the stand-down order before we even pulled out of the parking lot.

Still... the data reported by the subject's Spot unit and the way it was communicated by the Sheriff's Department posed certain challenges.  Since we're likely to receive future call-outs based on Spot 911 activations, all SARTECH I and SARTECH II members should work through the following navigation challenge.  Consider how you would do this in the field.

The subject's location reported by his Spot unit was relayed by the Sheriff's Department as:

39.4 min 43.8 sec 105.12 min 36 sec

Your challenge is to navigate to the subject's location.  Here's your homework assignment:

1. What datum does Spot use?

2. Translate these geo coordinates to UTM/NAD 27 CONUS.

3. How far apart are the NAD 27 CONUS and WGS 84 coordinates for this location?

4. Find this location on your map and describe it.

Here are the answers I got:

A1.  Spot uses WGS84.

See this web page:

http://www.findmespot.com/en/spotlight/index.php?option=com_content&view=article&id=90:tech&catid=12:faq&Itemid=22

A2. The geo coordinates translated to UTM/NAD 27 CONUS coordinates are: 13 S 0481885/4325338

I did the conversion using my Rino by:

1. Initially setting the units to Position Format = "hddd mm'ss.s" and  Map Datum = "WGS84"
2. Entering a waypoint with the given coordinates realizing that "39.4 min 43.8 sec" should be "39 deg 4 min 43.8 sec" and that "105.12 min 36 sec" should be "105 deg 12 min 36 sec"
   
3. Changing the units to Position Format = "UTM UPS" and Map Datum = "NAD27 CONUS"
4. Viewing the converted geo coordinate data for the waypoint.
   

I determined this by doing the conversion twice and measuring the distance between the 2 results.

A4. The subject's reported location is just east of Trailcreek Road about one half mile south of the intersection with Road 367.

Go to http://maps.google.com/ and enter this location in the search box: "+39 4 43.8 -105 12 36"

 These are the answers I got.  Please let me know if you got something different!!!