Every layer of your comms plan I write about, GMRS, ham, mesh, still depends on a working radio and a charged battery. It is worth having something that depends on neither, for the moment both of those fail at the same time.
Radios Fail, Batteries Die, Plan for Both
A dropped radio, a dead battery with no way to charge it, or simply being separated from your gear during an evacuation are all realistic ways your primary plan stops working at the exact moment you need it most. A non-verbal fallback costs nothing and never runs out of charge.
A Simple Whistle Code Anyone Can Learn
Three short blasts is a widely recognized distress signal, and building two or three more simple patterns on top of that, one for I’m okay, one for come here, one for stay put, gives your family a working vocabulary that carries much further than a shout and needs no equipment beyond a cheap whistle in every go-bag.
Mirror and Flashlight Signals for Line of Sight
A signal mirror can be seen for miles in the right conditions, and a flashlight works the same way after dark. Three flashes repeated is a simple, memorable distress pattern that anyone in the family, including young kids, can learn and use without any radio knowledge at all.
This Is a Supplement, Not a Replacement
None of this replaces the actual radio-based plan I lay out in what a real SHTF communications plan actually looks like. It is the layer underneath the layer, the thing you fall back on only once your real plan has already failed, and it is worth five minutes of practice so it is not being learned for the first time in an actual emergency.
For the fuller picture on building real emergency communications capability, see my Emergency Communications and Preparedness pillar page.