Accidental PLB activation

View previous topic View next topic Go down

Accidental PLB activation

Post  Col Douglas on Sun Aug 06, 2017 8:15 am

Had an incident yesterday that is worth reporting.

We are detecting in the Pilbara area at the moment, and while out in a semi-remote area my PLB activated. This was unknown to me at the time because my PLB in kept in a case on my harness and the flashing strobe was not visible. The emergency services contacted my son who is second on the notification list, because they couldn’t contact my wife (first on the list). She is out here too.
Naturally the call frightened the hell out of my son, who asked the ES to delay the search until he could contact his mother (he knew that we were out here with another couple, and were all in constant radio contact, and I would only activate the PLB as the absolute last resort). They were not happy to wait but they gave him a few minutes and he managed to contact my wife (back at our camp) who was then able to radio me and I turned off the PLB.

The device is a KTI SA2G with GPS. KTI says that there have been other cases of PLBs being activated by metal detectors, but only if the device gets too close to the coil, especially underneath it. They say that the only way to prevent this is to wrap the device in some sort of ferrous foil. The issue apparently applies to all brands of PLBs.

After thinking about what may have caused the issue, I realised that when I’d finished detecting in one area, and prepared to move to another area I had inadvertently either not turned off the ZED (or accidentally switched it on again) when it put it in the back of the Landcruiser; then when throwing my harness on top of the machine the PLB must have been near the coil (possibly on top of it).

I’ve heard of GPSs being destroyed by getting too close to a coil, but was unaware of this potential problem with PLBs.

What did impress me about all this was how quickly the Emergency Sevices responded and how accurately they were able to pinpoint my position. My son and wife also commented on their calm and helpful professionalism when they were contacted.

Hope this is of interest.

Col

Col Douglas
New Poster
New Poster

Number of posts : 15
Registration date : 2009-10-25

Back to top Go down

Re: Accidental PLB activation

Post  goldtalkleonora on Sun Aug 06, 2017 8:57 am

Hi Col, that's a very interesting post. How could we confirm the detector setting off the PLB??...Minelab perhaps?? Just something i would like to follow up and get the word out to people.
avatar
goldtalkleonora
Seasoned Contributor
Seasoned Contributor

Number of posts : 163
Registration date : 2015-06-01

http://www.goldtalkleonora.com.au

Back to top Go down

Re: Accidental PLB activation

Post  Guest on Sun Aug 06, 2017 9:19 am

Certainly handy to know. Will be sure to keep them seperate where needed.

Guest
Guest


Back to top Go down

Re: Accidental PLB activation

Post  Col Douglas on Sun Aug 06, 2017 9:38 am

goldtalkleonora wrote:Hi Col, that's a very interesting post. How could we confirm the detector setting off the PLB??...Minelab perhaps?? Just something i would like to follow up and get the word out to people.

G'day Tony,

I'm almost certain the metal detector was the cause, because when I moved to the new site to detect, and I took the Zed out of the vehicle, it was turned on. At this stage of course I didn't know that the PLB had been activated but I just reprimanded myself for not turning off the machine.

When the PLB is activated there is a flashing strobe, but I have it stored in a little case so I couldn't see that. I have since wrapped it in aluminium foil. The KTI tech said this was not sufficient and that it need to be wrapped in a ferrous type foil. I still think the aluminium foil, although maybe not preventing it from activating, would (you would think) attenuate its transmission signal.

I think it has to be very close to the coil for an activation to occur. However the KTI tech seemed to be well aware of the problem, though no one seems to have mentioned it. Maybe one solution would be for KTI to line the little case that they provide with the device with an appropriate foil.

Col

Col Douglas
New Poster
New Poster

Number of posts : 15
Registration date : 2009-10-25

Back to top Go down

Re: Accidental PLB activation

Post  Digginerup on Sun Aug 06, 2017 10:17 am

Good post, any issue with accidental activation of PLB by metal detector operation is a subject that certainly requires investigation, other than the fact accidental activation's would be a waste of valuable resources and must be a real pain in the ass for emergency services what happens in terms of charges and costs in an accidental/false activation, please keep us posted if you can get any info from the PLB people or minelab.

Wayne. cheers
avatar
Digginerup
Management

Number of posts : 2361
Registration date : 2012-05-17

Back to top Go down

Re: Accidental PLB activation

Post  peterinaust on Sun Aug 06, 2017 7:46 pm

Wow, thanks for posting. I keep my PLB at the back of my harness in the little pouch that comes with the harness, the battery carrier for the GPX I think.
I'll will be following this post if any more comes out. In the mean time will be extra care full. I would never have thought that this could happen!

peterinaust
Good Contributor
Good Contributor

Number of posts : 114
Age : 69
Registration date : 2012-01-21

Back to top Go down

Re: Accidental PLB activation

Post  Nightjar on Mon Aug 07, 2017 3:03 am

Maybe this very important post should be pinned until such time as a positive solution is found to prevent this happening?
avatar
Nightjar
Contributor Plus
Contributor Plus

Number of posts : 2009
Registration date : 2008-10-25

http://s4.zetaboards.com/Gold_Detecting/index/

Back to top Go down

Accidental PLB activation

Post  Col Douglas on Tue Aug 08, 2017 6:51 pm

I have contacted KTi and have received a response.

This is what I asked:

Several days ago while prospecting with a metal detector in the Pilbara in the north of Western Australia my PLB (a KtiSA2G) activated without any input from me. Fortunately the Emergency Services was able to ascertain that the activation was accidental before launching a rescue operation.

I contacted KTi by phone after the event for advice on what I should do. The tech advised me that activation of a PLB with a metal detector is quite possible and that KTi in fact had done some tests using a metal detector confirming this and he further said that the only solution was to wrap the device in a ferrous type foil (aluminium foil is not sufficient).

I've posted the incident on several prospecting forums and it has generated quite a bit of interest.

For the purpose of accuracy could you give me the latest information that you have regarding the possible activation of a PLB by a metal detector. In particular:

1. How close can the PLB be to the metal detector coil (above and underneath) without the possibility of activation?

2. What is the best way of protecting the PLB?

3. Any other information that would be of interest to a metal detector operator when using a PLB.

I will post your responses so that prospectors carrying a PLB and using a metal detector are aware of the precautions that they have to take.

Thanks for your anticipated response.

Col



This is the response from KTi:


Hello Col,

We have not conducted detailed research into this matter however we are happy to provide some assistance.

The safe distance from metal detector equipment will depend on the emitted field strength, pulse width and pulse rate. It appears that some modern metal detectors emit extremely strong magnetic fields and we understand that all three of the above factors are user-programmable in some devices.  Also the field directionality may vary significantly between devices as will stray radiation along wiring to other parts of the metal detector and battery.  Our very limited testing of one specific model did demonstrate that the field strength was considerably stronger 'beneath' the search coil than 'above' or to the sides. Field alignment is also a very significant factor and worst case must be considered for reasons of practicality.  We have no knowledge of the emission characteristics of specific devices and recommend you refer to data applicable to the equipment you use.  The one particular Codan unit we tested was capable of activating a PLB within 300mm beneath the search coil with factory default settings.

In terms of our general recommendation for this class of equipment: Considering a worst case scenario where pulses are repetitive and where pulse width / repetition rate fall in the region of 4.5 microseconds to 35 microseconds we recommend a maximum field of 50 microtesla.  Pulses outside this window are far less likely to be problematic however we recommend avoiding exposure to alternating fields exceeding 1 millitesla and static fields exceeding 10 millitesla. Whilst these figures tend toward conservative it should be noted that magnetic fields can easily be distorted and thus effectively magnified by the presence of other nearby metallic objects, including non-ferrous materials.

Enclosing a PLB within a magnetically shielded container should provide significant improvement however we have no numeric values to offer.

Regards,

Mark
.


Make of it what you wish, but in summary, there is no doubt that a metal detector can accidentally activate a PLB, and I can only suggest we should keep our PLB as far away from the coil as practicable.

Col

Col Douglas
New Poster
New Poster

Number of posts : 15
Registration date : 2009-10-25

Back to top Go down

Accidental PLB activation

Post  sandy2010 on Wed Aug 09, 2017 1:08 pm

Interesting post.......
Surely it would be easy to install an audible alarm system similar to what we have on our mobile phones ????

sandy2010
Contributor Plus
Contributor Plus

Number of posts : 794
Age : 76
Registration date : 2010-06-25

Back to top Go down

Re: Accidental PLB activation

Post  GoldnQuartz on Wed Sep 06, 2017 10:33 am

Very interesting for sure.

Placing the PLB in an iron cage with stop the electro-magnetic effects of the pulse induiction EM machines. This shielding is called a "Faraday Cage"

You should be able to fashion one easily by getting a thermo-insulation bag, the shiny foil-lined type for cold storage from supermarkets etc, and cutting and fashining something out of that but it will need to enclose the PLB completely.
Another alternative - also light weight, is to use some wire fly screen mesh, stainless steel, or whatver, you'll have to sew the panels together using a strand or two of the wire, and I would then line it so the device dsoesnt contact the sides, but you should be able to make it so you can still clip it on.

If that helps.

Cheers, GnQ

GoldnQuartz
Contributor
Contributor

Number of posts : 28
Registration date : 2016-04-07

Back to top Go down

Re: Accidental PLB activation

Post  Lindt on Thu Sep 07, 2017 12:34 am

I have a KTI PLB for kayaking. What's reassuring is the fact that you received a detailed response from KTI rather than a generic "Every customer is important to us.........." palm off. An Australian company as well.

You'll probably want to take the PLB out of it's shielded case if you decide to use one before activating as the signal to the satellite may also be blocked.

Lindt
Contributor
Contributor

Number of posts : 77
Registration date : 2013-11-21

Back to top Go down

Re: Accidental PLB activation

Post  adrian ss on Wed Sep 13, 2017 9:54 pm

Hmmmm. I just read this topic.
I purchased a KTI SA2G-GPS a while ago, Has not arrived yet.
So did I choose incorrectly?
avatar
adrian ss
Contributor Plus
Contributor Plus

Number of posts : 1312
Age : 71
Registration date : 2015-07-03

Back to top Go down

Re: Accidental PLB activation

Post  Lindt on Wed Sep 13, 2017 10:14 pm

adrian ss wrote:Hmmmm. I just read this topic.
I purchased a KTI SA2G-GPS a while ago, Has not arrived yet.
So did I choose incorrectly?

I looked at other units and decided the KTI was a good choice. Other brands may have the same sensitivity.

Lindt
Contributor
Contributor

Number of posts : 77
Registration date : 2013-11-21

Back to top Go down

Re: Accidental PLB activation

Post  adrian ss on Thu Sep 14, 2017 8:00 am

Just received word from AUPost that it will be delivered today.
This thread has been useful in that I now know to be wary of inadvertent activation due to EMI. scratch


PS:
Well there ya go; 5 mins after I posted,  AUpost delivered it to my door.

Hmmmmm ?
Somebody had  partially opened the box at one end without breaking the seal.

Double Hmmmmm :
The whistle is missing. Not a world ending disaster but annoying
avatar
adrian ss
Contributor Plus
Contributor Plus

Number of posts : 1312
Age : 71
Registration date : 2015-07-03

Back to top Go down

plb

Post  bowerbird on Fri Sep 15, 2017 5:39 pm

Hi Adrian ,did you get the lanyard with it ? the whistle is in the snap connector, very small , cheers BB

bowerbird
New Poster
New Poster

Number of posts : 9
Age : 66
Registration date : 2014-02-26

Back to top Go down

Re: Accidental PLB activation

Post  adrian ss on Sat Sep 16, 2017 7:46 am

Well there ya go. Yep it is small allright.
Thanks BB
avatar
adrian ss
Contributor Plus
Contributor Plus

Number of posts : 1312
Age : 71
Registration date : 2015-07-03

Back to top Go down

Re: Accidental PLB activation

Post  mintcar on Wed Oct 04, 2017 6:30 pm

Hi all I have only just arrived at this post sorry for delay, I have had a Kti plb since May 2015 in June 2016 in back country the rescue chopper arrives I was using a 7000 the plb was in my backpack it had activated its self, I contacted kti and returned it to them in Aust and they contacted minelab to do some tests they returned it to me and said the kti should not do that again I am very careful not to have them close to each other hope this helps

mintcar
New Poster
New Poster

Number of posts : 14
Age : 74
Registration date : 2009-11-23

Back to top Go down

Re: Accidental PLB activation

Post  adrian ss on Wed Oct 04, 2017 9:00 pm

Be handy to know what frequency and field strength EMI is required in order to activate this unit. I mean just having it in the car is subjecting it to some pretty severe low frequency magnetic fields.......Easy enough to run some tests I guess.

Also If you are out in the scrub and have a PLB with you then you should have it within reach and where you can see it. That way you will know if it activates inadvertently and will be able to switch it off before emergency services mobilise.


The next day 05/10/17

My Infinium, Sand Shark, SDC2300, CS4PI, did not set it off with the plb positioned a few inches from the coils.

The Inf field strength measured approx 450mG three inches from the centre of the 8 inch mono.
The 2300 measured approx 200mG three inches from the centre of the coil.
avatar
adrian ss
Contributor Plus
Contributor Plus

Number of posts : 1312
Age : 71
Registration date : 2015-07-03

Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum