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Personal Locator Beacons from the Rescuer’s Perspective

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Offline DesertRatShorty

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Personal Locator Beacons from the Rescuer’s Perspective
« on: October 10, 2017, 07:11:17 PM »
Interesting albeit somewhat dated article on Personal Locator Beacons from the Rescuer’s Perspective, that sheds some light on the issue of PLB vs two-way communicators. Some interesting points:

"The fundamental problem is that neither coordinate came with an estimate of the certainty, or possible error." -- The PLB was off by up to 1 km and the rescuers did not know which side of a swollen creek the subjects were on.

"In the face of uncertainty about the position of the subjects, the team fell back on good SAR training – cover all the bases" -- The implication is that had the rescuers known the subjects' location with more certainty, the rescue would have been more targeted and efficient, not to mention economical.
I roamed and rambled, and I foller'ed my footsteps
   To the sparkling sands of her diamond deserts
   And all around me a voice was a'sounding
   This land was made for you and me

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Offline CC

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Re: Personal Locator Beacons from the Rescuer’s Perspective
« Reply #1 on: October 10, 2017, 10:42:35 PM »
Thanks!  That was an interesting read, and a nice dose of reality after reading the marketing copy from the makers and sellers of the PLB. 

I think that while the location function of their device failed the subjects of this article, the important thing to note is that without a PLB, their need for rescue could have gone unknown for a much longer time that the 24 hours that it took for them to be found with the PLB.  Assuming they had filed a trip plan with someone, it would not be until they were overdue for a period of time until the search would be initiated.

It's also notable that filing a detailed trip plan with the contact person listed on the PLB registration is important, so the SAR team can quickly learn who and what they are looking for, and where they might expect to find them.

-Chris

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Offline House Made of Dawn

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Re: Personal Locator Beacons from the Rescuer’s Perspective
« Reply #2 on: October 10, 2017, 11:44:46 PM »
Interesting albeit somewhat dated article on Personal Locator Beacons from the Rescuer’s Perspective, that sheds some light on the issue of PLB vs two-way communicators. Some interesting points:

"The fundamental problem is that neither coordinate came with an estimate of the certainty, or possible error." -- The PLB was off by up to 1 km and the rescuers did not know which side of a swollen creek the subjects were on.

"In the face of uncertainty about the position of the subjects, the team fell back on good SAR training – cover all the bases" -- The implication is that had the rescuers known the subjects' location with more certainty, the rescue would have been more targeted and efficient, not to mention economical.

Yep. I've been following that author for awhile now. His skillset is amazing and his blog is excellent: it's informed by real world experience and it's extremely well-articulated.

One weakness of emergency beacons that crops up again and again in actual SAR reports is the unreliability of ALL these units' initial location fixes. The first report comes from radio triangulation using 406MHz signals, next comes the GPS fix.  The radio fix, which is dependent upon how many and what type of satellite is communicated with at any given transmission, almost always gets more accurate with each iteration. The GPS fix is highly susceptible to interference from impermeable landscape features, or moisture, or even a poorly positioned human body. Some units have separate low-power homing beacons that work pretty well in all conditions, but they have a range of only about 2-3 miles, so even if your unit is equipped with one, a SAR team needs to get at least that close to find you using the homing beacon. The problem lies in the fact that, even if your unit has a homing beacon, the initial 406 MHz and GPS fixes can be inaccurate by a factor greater than the range of that beacon. And in some cases, it's taken SAR teams almost 24 hours worth of 406 MHz and GPS interations to get an accurate location fix on a sheltering-in-place subject.  Which means the initial search can be significantly misdirected. One recent improvement: units that allow for an higher quality external GPS (which many hikers are already carrying) to be mated to the PLB. Theoretically, that might improve the reliability of the GPS signal.

So with the unreliability of initial fixes in mind, one question I've often asked myself is: how valuable would the messaging capability be in a SAR situation? Let's say, like the climber who found himself cliffed out on Elephant Tusk a few years ago, or in a situation where one was envenomated by a dangerous animal or poisoned by something else, would it be useful to be able to text someone the specific location and nature of the emergency? What if you could inform the SAR team from the get-go that air-evac was necessary? Even if the message took a few hours longer to reach the relevant local rescue authority? What if it took 8 hours longer to reach people that could do something about it? 12 hours? Tricky questions, those.

Some of the answers may depend upon what kind of emergency you think you'll get yourself into. Getting lost or stranded by field conditions, breaking a bone or otherwise damaging your body in an accident, suffering an animal attack (what kind?), or some internal pathology like severe giardia or heat stroke or heart attack, the list goes on. And the answers may differ for each kind of distress and for each person doing the answering.

The choices involve the type of beacon signals that the unit can send (406 MHz triangulation, GPS, 121.5 MHz homing beacon, original text message via satellite, pre-programmed text messages by satellite, emergency strobe light), the type of sateIlite network used (COSPAS-SARSAT vs. commercial networks like Iridium), the entity which will be receiving your signal (government vs. corporate), and whether the unit requires a time-sensitive fee-based service plan. 

Personally, I've been using a McMurdo FastFind 210 for over a decade. It's registered with NOAA in perpetuity (as long as I update my registration) and I know my SOS will go straight to Langley if I ever activate it. I've thought a lot about the alternatives, but so far I've stuck with the McMurdo PLB because it cost me a pretty penny when I bought it and it can do most of what I think I need. 95% of my wilderness travel is done solo, so I also carry three 90-second red smoke signals (less than half an ounce each). And a Petzl e+LITE with a red strobe on it. And a mirror (on my compass). And a whistle. And I know how to make and use various international rescue signs and administer wilderness first aid. And I never leave camp without carrying all those things, plus an emergency metallized bivy. And, as CC wisely recommended, I always leave detailed copies of my plans and maps of my intended routes with my wife and brother, both of whom are listed as contacts in my NOAA registration. The point being, if an emergency hits, I'm prepared to survive and make myself easy to be found for as long as I'm conscious.

But in the final analysis, each person needs to make their own very personal choices about the risks they're willing to undertake, and which exact safety measures give them comfort.
« Last Edit: October 11, 2017, 12:37:35 AM by House Made of Dawn »
"The trick, William Potter, is not minding that it hurts."

 


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