SOS

SOS is an internationally recognized distress signal, meaning an urgent request for rescue to save lives.

SOS

Overview

SOS is an internationally recognized Morse code distress signal (··· --- ···), used by ships, aircraft, and individuals to request rescue when life or property is threatened. It was officially adopted at the 1906 Berlin International Radiotelegraph Conference and remains widely used in emergencies through various communication means today.

Main Content

Historical Background

The SOS signal emerged with the development of wireless communication in the early 20th century. It was proposed by an Italian delegate in 1903 but rejected, and became an international standard in 1906 through a German proposal. The signal gained widespread public recognition during the sinking of the Titanic in 1912, when SOS was used. Previously, CQD (general call + danger) was used, but SOS became the standard due to its simplicity and ease of identification.

Meaning and Interpretation

SOS is not an abbreviation of any specific words. It is a pattern (··· --- ···) chosen for being the simplest and least confusing in Morse code. Popularly interpreted as "Save Our Souls" or "Save Our Ship," these are backronyms. Officially, it has no meaning and functions solely as a distress signal.

Usage Methods

SOS can be transmitted in various ways:

Radio communication: Repeat three short signals, three long signals, and three short signals in Morse code.
Visual signals: Use flags, flashlights, laser pointers, etc., to convey the light pattern.
Audio signals: Use whistles, horns, sirens, etc., to convey the sound pattern.
Ground signals: Write SOS large in snow or sand, or mark it with stones or branches.
Digital communication: Use the SOS keyword in emails, text messages, satellite phones, etc.

International Regulations

The International Maritime Organization (IMO) and the International Telecommunication Union (ITU) designate SOS as the official distress signal. Ships and aircraft are required to have SOS receiving equipment, and any vessel receiving an SOS must immediately proceed to rescue. False signals are subject to legal penalties.

Modern Applications

Smartphone SOS feature: Most smartphones offer an SOS feature that automatically sends location information to emergency contacts when the power button is pressed multiple times.
Apple Watch: Automatically sends SOS after fall detection or crash detection.
Vehicle SOS: Luxury cars like BMW and Mercedes are equipped with eCall systems that automatically send rescue requests upon collision.
GPS beacons: Personal Locator Beacons (PLBs) transmit SOS via satellite.

Latest Trends

As of 2024-2025, SOS systems are becoming more sophisticated through integration with digital technology. Since 2024, the European Union has mandated eCall systems in all new cars, which automatically send SOS signals. Additionally, AI-based distress signal analysis systems have been introduced to filter out false signals and identify real emergencies more quickly. The widespread adoption of SOS features in smartwatches and wearable devices has significantly improved personal safety. In particular, by 2025, the global SOS network utilizing satellite communication has expanded, enabling rapid rescue even in polar or mountainous regions. Furthermore, drone-based SOS signal detection and rescue systems have entered the practical stage.

SOS