Morse Code TranslatorHow SOS is sent
SOS is a prosign. That means the letters S, O and S are sent as one long signal with no gap between them. On paper you may see it with a bar on top or written as <SOS>. Here is how it compares to the three letters sent one by one:
- As one signal:
···−−−··· - As three letters:
··· −−− ···
In real life, both are understood. What matters is the rhythm: short short short, long long long, short short short. Then a pause, and again.
Morse code for help: how to signal SOS
Use whatever you have. The pattern works with sound, light or touch.
- Flashlight or phone light: three quick flashes, three long ones, three quick ones. Pause, then repeat.
- Whistle or horn: three short blasts, three long blasts, three short blasts.
- Knocking or tapping: tap three times fast, three times slow, three times fast.
- Mirror: catch the sun and flash the same pattern toward a plane or boat.
Make a long signal about three times as long as a short one. Do not rush. A clear, slow SOS is better than a fast one that no one can read.
In an emergency, call 911 in the US, or your local emergency number, if you can. Morse code is a backup, not a first choice.
The history of SOS
Before SOS, many radio operators used CQD. The Henry Ford museum says Marconi operators adopted CQD in 1904. Then on November 3, 1906, the International Radiotelegraphic Convention chose SOS as the world distress signal. Smithsonian Magazine says it was chosen because it is easy to send and easy to recognize.
The rule took effect in 1908, and ships took it up bit by bit, the Smithsonian Libraries note. The Henry Ford tells how the first SOS was sent on August 11, 1909. Theodore Haubner, the telegraph operator on the SS Arapahoe, sent both SOS and CQD when his ship was in trouble off Cape Hatteras. The ship got help about twelve hours later. In 1912, the Titanic sent SOS as it sank.
In 1999, a satellite based system replaced SOS on large ships. Even so, SOS is still the best known distress signal in the world.
What SOS means, and what it does not
You may have heard that SOS means "save our souls" or "save our ship". Those came later. SOS does not stand for any words. It was picked for its sound.
Want to learn more letters? See the Morse code alphabet, or read what Morse code is and whether it is still used.
Frequently asked questions
What is SOS in Morse code?
SOS is three dots, three dashes and three dots: ···−−−···. It is sent as one signal with no gaps between the letters.
What does SOS stand for?
Nothing. It is not short for "save our ship" or "save our souls". Smithsonian Magazine says it was picked because it is easy to send and hard to mistake for anything else.
When was SOS adopted?
The International Radiotelegraphic Convention chose SOS on November 3, 1906. The rule took effect in 1908, and ships began using it over the next few years.
How do I signal SOS with a flashlight?
Make three short flashes, three long flashes and three short flashes. Make the long flashes about three times as long as the short ones. Pause and repeat. You can also use the Light button above with Repeat turned on.
Is SOS still used?
Large ships switched to a satellite based distress system in 1999, Smithsonian Magazine says. But SOS is still known around the world, and a light, whistle or radio SOS can still get attention.