I'm confused. At first you say don't use grid references then you say do.
"mountain rescue services". Not relevant to all of us and W3W is easier to use. Let Mountain Rescue convert it, they're far less likely to muck it up than someone who doesn't use lat/long on a regular basis. In fact I'd wager that if you took several 'Joe Bloggs' out of their home ground, put them somewhere wet, cold and windy and getting dark. Threw in an emergency involving blood and lots of screaming then asked them to note and convey a collection of twenty characters over a bad mobile phone connection not many would get it right first time. Lat/long is not an intuitive system for the uninitiated.
This was done to death a few months ago. Many if not most emergency services have or are moving to to W3W which being a collection of words rather than an unfamiliar string of digits (to most) is LESS likely to get mixed up. I use lat/long for a living so think I've a good idea of what comes more naturally, proper words or trying to 'chunk' 20 numbers and letters that have no mnemonics or other aides memoir to keep them clear.
Sorry who mentioned lat/long???
Ud have to be crazy to ever think that would be very clever idea.
I was talking a 6 figure grid ref, 8 digits is all u need 2 intials for sheet and 6 figures.
I'd say fairly idiot proof, it took u 4 digits to unlock ur phone and u manage that.
If u really can't cope with that I'd be surprised if u can tie ur shoe laces.
Using w3w u will likely have to spell every word phonetically, many off he words have more than 8 letters.
Also the accuracy off w3w actually plays against u, stand in same spot and hold phone full reach either side probably a good chance ur w3w 'code' will have changed.
completely and that's u standing in the same spot.
if ur walking about to try and get the strongest signal ur 'reference' will be constantly changing.
i just refreshed my +F recently with a very good instructor who specialises in forestry training and ex mountain rescue member and he was pretty scathing about w3w in a remote forestry environment, fine in more urban areas.
Each to here own thou
Sorry but w3w, did seem a handy thing at 1st, but with modern phones with GPS apps I really can't understand why ud pass on 6 numbers ( so six words) for 3 words ( so 12 words at a minimum possibly 20+)
Plus as stalkers if u wanted to record culled deer a 6 or 8 figure grid reference is far handier u can see straight away deer shot close together or even how far apart by the 1st 2 numbers off each sequence.