How to signal for rescue, offline on iPhone
Last updated 2 June 2026
If you need rescue, signalling is how you get found: a repeated pattern that reads as 'help', not noise. The universal call is SOS (three short, three long, three short), by light, mirror, whistle, or sound. On the iPhone, Ferdinands Outdoor Companion (FOC) carries a Morse and signalling reference, fully offline and free.
Signals that read as 'help'
Rescuers look for things that are clearly human and repeated: three of anything (three whistle blasts, three fires, three flashes) is a recognised distress sign. SOS in Morse is the same idea encoded: di-di-dit, dah-dah-dah, di-di-dit. A mirror or phone screen can flash sunlight a surprising distance; a whistle carries far further than your voice and costs no breath.
Signalling in FOC
FOC includes a Morse code reference (SOS plus the full alphabet) and signalling guidance, alongside more than 40 survival and outdoor articles, all stored on the device. It works in airplane mode by design, has no ads, no in-app purchases, and no tracking, and reads in German, English, or Danish. A reference is a companion, not a substitute for telling someone your plan.
How it compares
| What helps | FOC | A signal you half-remember |
|---|---|---|
| The SOS pattern, exactly | Yes | Maybe |
| Full Morse alphabet | Yes | No |
| Works with no signal | Yes | n/a |
| No ads or tracking | Yes | n/a |
| Reads in DE, EN, DA | Yes | n/a |
Frequently asked questions
What is the universal distress signal?
SOS: three short, three long, three short, sent by light, sound, mirror, or whistle. More generally, three of anything (three blasts, three fires) reads as a call for help.
Does FOC work without signal?
Yes. FOC stores everything on the device, so its Morse and signalling reference works in airplane mode, exactly when you have no bars.
How do I signal with no equipment?
A whistle, a mirror or phone screen flashing sunlight, or three of any repeated sign. FOC's reference covers SOS and Morse so you can send a clear, recognised pattern.
Is FOC free?
Yes. FOC is free, with no ads, no in-app purchases, and no tracking, and it works fully offline.
Related
Sources
This is general reference, not medical, safety, or professional advice. Skills like first aid and foraging carry real risk. In a real emergency, call your local emergency number (112 in the EU, 911 in the US).