SOS at a glance
- One signal:
...---...with no pauses between the letters. Use this when you signal for help with sound or light. - Three letters:
... --- ...with a space after each letter. This is SOS written as text, the way the Morse code translator shows it.
In both forms S is three dots and O is three dashes, so you only need to remember one pattern: short, short, short, long, long, long, short, short, short. You can check every other letter on the Morse code alphabet chart.
How to signal SOS
If you can call or text emergency services, do that first. A signal is for when you cannot, and it can also help rescuers find you. The player on this page only plays the pattern on your device; it does not contact anyone.
- With a light: a flashlight, a phone torch or a car's headlights. Three short flashes, three long, three short, then pause and repeat. A phone torch drains the battery you may need for a call, so use it sparingly. If your car is stuck in snow, keep the exhaust pipe clear and run the engine only in short spells; the headlights and horn also drain the battery.
- With sound: a whistle carries farther than your voice and takes less effort. Blow three short blasts, three long and three short. In the mountains, the usual distress call is six blasts or flashes spread over a minute, then a minute's pause; rescuers answer with three.
- By tapping: knocks are all short, so they cannot make a clear dash. Tap in groups of three instead, then pause and repeat: three of anything is a widely used call for help. If you are trapped, tapping on a pipe or a wall is better than shouting, which makes you breathe in dust.
- On the ground: write the letters SOS as large as you can in an open space, with rocks, branches or by stamping in snow, so it can be seen from the air.
Keep repeating the signal with a pause between rounds, which tells anyone watching or listening where the pattern starts. Repeat above plays it the same way, with a two-second pause.
Why SOS is three dots, three dashes, three dots
SOS was adopted as the international distress signal at the International Radiotelegraph Convention in Berlin in 1906, and took effect on July 1, 1908. It replaced several older calls, including CQD, which stayed in use for several more years, especially among operators working for the British Marconi company.
The pattern was picked for how it sounds, not for what the letters spell. Nine elements with short, even gaps between them, in a short, long, short rhythm, are easy to recognize and hard to confuse with ordinary messages. Because it is sent as one unbroken signal, radio operators write it as SOS with a line over the letters to show the letters run together.
When the Titanic sank in April 1912, its radio operators sent both CQD and SOS. The disaster greatly increased public awareness of SOS, which had already been the international standard since 1908.
Is SOS still used?
On February 1, 1999, the Global Maritime Distress and Safety System (GMDSS) came fully into force for ships covered by the SOLAS convention, mainly passenger ships and cargo ships of 300 gross tonnage or more on international voyages. Those ships now call for help with satellite beacons and digital radio instead of Morse code, and voice radio uses the spoken call Mayday.
SOS itself is still an official distress signal. The international rules for preventing collisions at sea (COLREGs) list SOS in Morse code, sent by any signaling method, as a distress signal, and forbid using it for anything else. Survival and outdoor guides still teach it because it works with almost anything that can make a flash or a sound. Only send it in a real emergency.