1. How AIS Devices Share a Ship's Location by Radio Waves
Many modern ships are equipped with a device called AIS. This device automatically sends out radio waves containing the ship’s name, current location, speed, direction, and destination to other nearby ships [1]. Because of this, even if it is raining or dark and you cannot see with your eyes, you can know where nearby ships are and which way they are heading.
2. How the Titanic Disaster Led to Ship Safety Rules
The creation of these safety devices was influenced by a major accident in the past. In 1912, the large ship Titanic hit an iceberg on its first voyage and sank, causing many deaths. After this disaster, countries around the world discussed creating rules for ship safety and signed the first treaty in 1914 [2]. This meeting, attended by 13 major maritime nations from Europe and America, established rules requiring lifeboats and 24-hour listening on distress radio frequencies. This event is the starting point of the International Convention for the Safety of Life at Sea, known as SOLAS, which continues to this day [2].
3. How AIS Was Developed and Added to the Rules
Long after the early treaties, technology for ships to exchange information via radio waves developed in the 1990s. In 2000, the use of AIS was added to the rules for ship safety [3]. The technology was reviewed by the International Maritime Organization (IMO) as an amendment to Chapter V of the SOLAS Convention. It was adopted at the 73rd Maritime Safety Committee (MSC73) in December 2000 [3].
4. Why a Specific Event Moved the Deadline for Installing AIS
Originally, the rules were meant to prevent accidents. However, the purpose later expanded. The requirement to install AIS had already been decided in 2000. But in 2001, a major terrorist attack occurred in the United States. After this, the idea that "we must prevent bad things done with ships" became stronger. As a result, the rules were revised in 2002, and the deadline for ships to install AIS was moved up [4]. While SOLAS was originally a treaty for "Safety" to prevent maritime accidents, this revision marked the start of its role in "Security" to prevent crime and terrorism.
5. How Far AIS Radio Waves Can Reach Over the Sea and Upwards
When AIS radio waves travel horizontally over the sea, they reach about 74 kilometers (about 46 miles). However, if the same radio waves are sent upwards, they can reach the International Space Station (ISS), which is at a height of 400 kilometers (about 249 miles) [5]. In fact, a machine to catch these waves is installed on the ISS, and research is being done to find the location of ships at sea from space [5]. It is like how your voice might not carry over a mountain, but if you shout from a high tower, it can be heard over the mountain. Note that radio waves and sound work differently, but the idea of height helping the signal travel is similar.
6. Which AIS Information Anyone Can See on Internet Maps
Not all information sent by AIS is restricted to special people. On internet map sites, anyone can see what kind of ships are currently sailing [6]. This means that a device meant for safety has also helped make some parts of sea traffic visible to the public.
7. Why Some Ships Do Not Appear on AIS Maps
AIS is very useful, but it is not the only thing used to prevent ships from colliding. According to guidelines from the International Maritime Organization (IMO), AIS is meant to add clues for navigation. It is not a replacement for radar, but a helper [7]. Also, not all ships have AIS. Pleasure boats, fishing boats, and warships may not have it. Even on ships required to have it, the switch might be turned off in certain situations [7]. Therefore, just because a ship does not appear on an AIS map, it does not mean there is no ship there. People working on ships use multiple clues, such as visual lookouts, radar, and AIS, to check the ships around them [7]. They are advised not to rely on AIS as the only source of information. Using AIS does not change the responsibility of the watch officer to follow the International Regulations for Preventing Collisions at Sea (COLREG) [7].
8. How You Can Look at Ships Near You on an Internet Map
Try opening an internet map site that shows ship locations with your family. Look for what ships are currently in the sea near where you live.