To signal for help without a phone, send SOS with a light, ...---...: three short flashes, three long, three short, then a pause, and repeat. With a whistle, a horn or anything that makes noise, use groups of three blasts with a one-minute pause between groups. In daylight, a mirror can flash sunlight at an aircraft or ship many kilometres away.
First: if you have any signal at all, call your local emergency number. These methods are for when you cannot.
SOS with a flashlight
SOS is the one Morse signal recognised almost everywhere, and a flashlight is the easiest way to send it.
- Three short flashes. About as long as it takes to say "dit".
- Three long flashes. About three times as long as the short ones.
- Three short flashes again.
- Pause for a few seconds, then repeat.
Send the nine flashes as one run, without longer gaps between the groups: ...---.... That unbroken form is the correct distress signal. Tap the code to hear the rhythm.
The most common mistake is making the long flashes too short. If short and long look alike, nobody will read SOS. Count in your head: short is "one", long is "one, two, three".
A car's headlights, a phone screen or a camera flash will do. MorseBeep's phrases page has an SOS button that turns your screen into a flashing signal, and on many Android phones it can flash the camera light too. Switch on "Repeat until stopped" in the settings so it keeps going.
Signals in threes
Mountain and wilderness distress signals are based on groups of three: three blasts on a whistle, three flashes of light, three shots, or three fires or piles of rocks laid out in a triangle. Send the group, wait one minute, and repeat until you get an answer.
A whistle is worth carrying for exactly this reason. It is louder than a voice, carries further, and takes far less energy than shouting.
The Alpine distress signal
In the Alps and in some other mountain regions, including the United Kingdom, the signal is six instead of three:
- Distress: six signals within a minute, one every ten seconds, by whistle, light or anything else. Then a minute's pause, then repeat.
- Answer: three signals within a minute, then a minute's pause, then repeat. If you hear three, you have been heard.
The Alpine distress signal was introduced in 1894 at the suggestion of Clinton Thomas Dent, and was soon adopted internationally. It is worth knowing both versions: whatever the count, a regular, repeated signal with pauses is clearly not natural noise.
Signalling with a mirror
On a sunny day, a mirror reflecting sunlight can be seen from very far away, which is why lifeboats and survival kits carry purpose-made signal mirrors with a sighting hole to aim them.
The difficulty is aiming. The reflected beam is narrow, less than a degree across, so you must point it precisely:
- Hold the mirror near your eye and look at the target, such as an aircraft or a ship.
- Stretch out your other arm and make a V with two fingers, framing the target.
- Tilt the mirror until the spot of sunlight lands on your fingers, then sweep it gently across the target.
Aiming with your fingers is less accurate than a proper sighting mirror, but it works. Even if you cannot flash SOS, a series of bright flashes towards a searcher will draw attention. Ordinary mirrors do not meet the requirements for lifeboat equipment, so if you spend time at sea or in remote places, a real signal mirror is a cheap and wise purchase.
Other ways to send SOS
- On the ground: stamp or lay out SOS in large letters in sand, snow or with stones, for searchers in the air.
- Sound: a car horn or a pot and spoon can send
...---...too. - Radio: on a marine radio, use the distress procedures you were trained for, starting with Mayday on voice.
Practise before you need it
The time to learn this is now, not in an emergency. Flash SOS on your screen once with the phrases page so you know how long "long" really is, and read what does SOS stand for for the story behind it.