Rab TILT and beacon interference

A few days ago I read BD's QC lab article on beacon interference (https://www.blackdiamondequipment.co...-interference/) which is good and you should read it. Anyhow, somewhere down at the bottom in one of the little pictograms it had a note to avoid "apparel with heating function, metal foils…" and it clicked in my head that Rab's TILT (thermo ionic lining technology -- basically a scrim that has titanium bonded to the fabric to reflect heat back to the body) is a lot like a metal foil.

I've got their Mythic G jacket (and the Mythic Ultra that I use as a belay parka) that I keep in my pack as a safety/injury puffy quite often and I wondered if having a beacon under the jacket would be a problem. (I usually wear my beacon in my pant's hip pocket, but it seemed pretty easy to test this and something to keep in mind wherever one wears the beacon).

I drug my kids to the local park since I wasn't skiing today and they were being a pain cooped up in the house since it's really cold (for the Puget Sound) outside.

I didn't do the most thorough test in the world but the basic setup was:
- I used an old Mammut Barryvox (the semi-transparent red plastic model, I think I bought mine in 2007 or 2008) as the sender beacon since I theorized that technology has advanced the most in signal acquisition and sending technology hasn't changed much.
- I used a Pieps Pro BT as the search beacon (that I got in 2020 as a warranty replacement from Pieps at the beginning of the slide-recall debacle). It has the most up to date firmware and I held it the same full arm extension out from my body in all six searches. For both searches I also had my iPhone in my left hip pocket and my Garmin Instinct2 on my left wrist (notably, without GPS tracking or any extra functions active).

For the first test I put the Barryvox on the ground, walked a long ways away (later measured it at 62m) and turned my Pieps on. It had no signal, which was what I wanted. I started slowly walking towards the Barryvox and picked up a signal. I marked the spot with a glove, turned the Pieps off and repeated that three times. All three times it found the signal in almost the exact same spot, which I measured to be 57m later.

I then went to the Barryvox, placed it inside my zipped up Mythic G jacket and put it back on the ground in the same orientation that it had been for the first test. Went back to the same starting point and started walking toward the Barryvox with the Pieps in search mode. Again marked the spot where I picked up a signal with a glove, went back to the start and repeated it twice more. Each time it found the signal at approximately the same spot (within a 1m circle). I later measured the furthest spot where it picked up a signal to be 48m from the Barryvox.

Interestingly when the Pieps did get a signal for the TILT-wrapped-Barryvox it reported distances that were similar to the distances at signal acquisition to the naked Barryvox (usually 55-60m). I don't have a way to understand if that's related to the elliptical shape of the beacon signal or more generally related to the interference from TILT.

One of my kids (who had insisted on dressing themself for this trip) was getting very cold and so I didn't test out finer/closer searching to see if there was an effect there, but I probably will at a later time. The BD article would suggest that it's probably not an issue as most of the problems are at the edges of signal acquisition and getting closer attenuates the effects, but I don't know for sure.

I'll admit I was hoping there'd be no difference in this whole endeavor and that I'd be able to put it out of my mind.

Things I'll test in the future:
Does having the jacket next to the beacon affect anything (ie what if I don't put the beacon in the jacket but merely a foot or so away from it to more aptly compare to how I wear it in my pants)
Does having the beacon inside the jacket affect fine searching
I might compare one of Rab's TILT sleeping bags with the jacket (does the increased amount of TILT affect the signal degredation?)

Here's a tl;dr from my IG:
Attachment 482875

Thanks for trying that out!
UIAA guidelines for EMI also specifically call out foil-lined jackets.
knowing that, I find it really disappointing that RAB came out with these jackets, specifically marketed at winter time use, where you are pretty likely to have an avalanche beacon, and they don’t, at a minimum, have a giant warning on the webpage.

I hadn’t thought about the difference if you are a beacon-in-pants person, so that could be a solution, if they are far enough apart (low pocket)

Thanks for testing this out! I’m still very curious about this and also bummed that rab doesn’t mention anything about it. They even have another new model featuring TILT this season(cirrus ultra).

ME has a new jacket out with metal in the lining that mentions ski touring in it’s description:
https://www.mountain-equipment.com/p...ed-mens-jacket

Tried to send ME an email about it and they basically admitted to not having tested it, telling me that why would I worry about this when my phone would cause more interference and basically telling me to fuck off. Was quite off putting and has made me quite wary of any of these products now.

Definitely concerning since the Rab products are more popular and plenty of people are out there using them for ski touring in avalanche terrain and probably not aware of the grey area of use that it is in. Interference is sketchy shit and only gets worse the more beacons are in close proximity. If you ever did this again I’d love to see you try with to beacons, one in each of your jackets.