International Code of Signals (INTERCO)
The International Code of Signals (INTERCO) is an international communication system used by seafarers aboard ships to convey important information related to navigation, safety, and other operational matters. It is a standardized system using various signals and codes to help overcome communication barriers caused by language differences between seafarers of different nationalities.
This signaling system standardizes messages in nine languages: English, Japanese, Norwegian, Russian, Italian, Greek, French, Spanish, and German. Even if the sender and receiver speak different languages, each language has a corresponding message associated with the same code.
Signal Code
INTERCO is useful when seafarers aboard a ship can hear or see each other. The code also includes procedures for initiating calls and formatting messages.
This article details the International Code of Signals, its brief history, its importance, and how it is used by seafarers and maritime professionals.
First, let’s understand what maritime signaling is. Maritime signaling is a system of communication between ships or personnel operating at sea using radio, whistles, and flags.
Aside from communication barriers (cell phone networks may not work overseas), maritime signaling helps ensure smooth communication and avoid errors caused by misunderstandings. Different signals are used for various situations and emergencies, and seafarers should be familiar with them.
A Brief History of the International Code of Signals (INTERCO)
Before the advent of the International Code of Signals, various maritime and private signaling systems were in use, such as the Marryat Signal Code of the mid-1850s.
From the early to mid-19th century, Britain, France, and the United States developed their own signaling systems, and the Royal Navy also introduced a flag signaling method.
The British Board of Trade established the International Code of Signals in 1855 and published it as the Commercial Code in 1857. The Code provides common signals, primarily using flags to convey distress messages, navigation requests, and ship identification.
With the booming maritime trade and shipping in the 19th century, the need for such a set of rules arose. Previously, signals were limited to specific regions or countries, leading to communication difficulties. Over time, the Code was revised to introduce new signaling methods, such as Morse code.
After World War II, the International Maritime Organization (IMO) actively worked to standardize maritime communications. The code was further developed, retaining the flag system while incorporating modern maritime technologies such as radio signals.
Today, the International Code of Signals is administered by the IMO, with a new edition published in 2005. The code covers visual signals or flags, auditory signals (such as whistles or horns), and radio communication protocols. These signals are universally recognized by all maritime personnel.
Signals Used in the INTERCO System
Signals can be divided into three categories:
- Single-letter signals are used for important, urgent, and general information.
- Two-letter signals are used for other information and are sometimes followed by a numeric complement to complete the message.
- Three-letter signals beginning with M are medical signal codes.
1. Flag Signals (Using a Specific Flag):
As the name suggests, flag signals use flags or pennants to convey important information. Before the invention of radio, people used one or two flags to communicate over long distances. In flag signaling, each flag or group of flags has a predetermined meaning or symbol. INTERCO maintains a set of standard flags and corresponding international alphabets, as well as a set of symbols.
Purposes of flag signals:
International distress signals, for example, using a flag to indicate an emergency.
Issuing navigational warnings, such as indicating a ship’s course or position.
Sending requests for assistance, such as requesting medical assistance or a tow boat.
Because flags are brightly colored and have unique patterns, each signal is easily distinguishable from a distance.
2. Morse Code (via radio or light signals):
A signal lamp, also known as a Morse lamp or Aldis lamp, is an optical signaling device that uses flashing lights for communication, typically using Morse code. British Royal Navy Captain Philip Howard Columbus invented a scheme in 1867 using a lantern to emit flashing dots and dashes, although his code was not identical to Morse code.
During World War I, the Germans employed an optical transmitter equipped with a red filter to transmit Morse code over a range of approximately five miles.
Today, signal lights create concentrated pulses of light by opening and closing shutters in front of them.
2. Morse Code (via radio signals or lights)
A semaphore, also known as a Morse lamp or Aldis lamp, is an optical signaling device that uses flashes of light (usually in Morse code) for communication. British Royal Navy Captain Philip Howard Coulomb invented a scheme in 1867 using a lantern to emit flashing dots and lines, although his code was not identical to Morse code.
During World War I, the Germans employed an optical transmitter equipped with a red filter to transmit Morse code over a five-mile range.
Today, semaphores produce concentrated light pulses by opening and closing shutters or using concave mirrors. They are still used on warships and air traffic control towers when radio communication is disrupted.
3. Flag Signaling
Flag signaling is another effective communication system when two parties are separated by a considerable distance. It uses visual signals, such as flags raised by hand, disks, paddles, poles, and other methods.
This signaling system became widely used in the 19th century and is still used today for refueling operations at sea, daytime emergency communications, and nighttime flares in lieu of flags.
4. Sound Signaling (Using a Ship’s Horn or Whistle)
Sound signaling, including the use of a horn or whistle, falls under the International Regulations for Preventing Collisions at Sea and can be used in situations where flag signals are not possible. In bad weather or low visibility at sea, the use of sound signals is essential to avoiding collisions and ensuring safe navigation.
5. Voice Communication (via Radio)
Voice communication via radio is the simplest form of communication. Many standard maritime communication phrases can be used to convey information to other crew members. This method of communication is very convenient and can be used even over long distances.
Components of the INTERCO System
The international signaling system uses a combination of signal flags, letters, and alphabetic symbols and includes the components listed below.
Alphabetic Code
Each letter of the alphabet has a specific flag that can be used alone or in combination to convey information.
For example, the A flag has vertical white and blue stripes, while the B flag is all red.
Twenty-six naval flags, each beginning with a new letter, represent a new message.
For example:
Alpha – “Diver, please stand down.”
Bravo – “I am receiving, disembarking, or loading hazardous cargo.”
Charlie – “Yes” (confirmation).
Whiskey – “I need medical assistance.”
Number Codes
There are 10 flag numbers, from 0 to 9, used to help identify ships. This system is used to distinguish between ships with similar names or to help identify ships within the same fleet class. This system also helps convey information such as coordinates, time, and speed.
Message Codes
These messages include predefined messages for specific situations, ranging from simple messages like “I am disabled and need assistance” to more complex messages that help quickly convey emergency information.
Special Signals
These signals indicate specific requests or actions, such as a vessel undergoing a tow operation or a vessel requiring medical assistance.
Collective Signals
These signals require the simultaneous hoisting of multiple flags to form a group signal representing a complete message. For example, “I’m in distress” can be represented by a group of flags, each representing a portion of the message.
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The Importance of the International Code of Signals
INTERCO establishes a global communications system that ensures the safety of seafarers and ships by enabling clear and rapid communication between ships or port authorities around the world. In emergencies such as collisions, medical emergencies, and groundings, accurate signaling is crucial to preventing accidents and saving lives.
The INTERCO system is comprehensive. It is not limited to a single communication method but provides multiple ways to signal ships, coastal stations, or authorities, including the use of flags, lights, radio, whistles, and more. Therefore, if one method fails, many others are available.
The International System of Signals (INTERCO) enhances maritime safety by ensuring consistent interpretation of symbols across the global shipping industry. In the event of a maritime threat, incident, or cybersecurity issue, if a ship is unable to communicate with nearby port authorities, contingency plans can be exchanged as necessary.
INTERCO also improves efficiency and streamlines operations within the shipping industry. It is also used for day-to-day operations, such as signaling maneuvers, reporting navigational hazards, and providing updates on vessel status.
Today, INTERCO is often integrated into navigation and communication systems, such as the Global Maritime Distress and Safety System (GMDSS), which automates most functions. However, INTERCO is a crucial component of safety training and emergency procedures.
Challenges of Using INTERCO
Despite its widespread use in the maritime sector, INTERCO still faces some limitations.
In rough seas with low visibility, visual signals can be difficult to interpret, and even radio signals are susceptible to interference.
All seafarers must be trained in the correct use of codes to ensure effective communication. Using the wrong code or signal in an emergency can have disastrous consequences.
Conclusion
INTERCO is an integral part of the maritime landscape; without it, the smooth flow of global maritime trade would be impossible. It enables seafarers and maritime professionals at coastal stations or ports to communicate effectively and clearly with vessels at sea and quickly dispatch assistance when needed.
By understanding and learning various signaling methods, such as the use of flags, Morse code, and radio, maritime professionals can improve emergency preparedness, enhance operational efficiency, and contribute to a safer maritime environment. This can be achieved by participating in INTERCO’s training exercises, which cover a range of scenarios from daily operations to emergencies.