top of page
  • Writer's pictureTravis Turgeon

Advantages and Limitations of AIS (and How to Bridge the Gaps)

Updated: Jan 19

"The easiest way to manipulate AIS data is to simply turn off the transponder. Once the system is switched off, it no longer sends or receives AIS data, allowing vessels to operate as dark ships."

earth from space automatic identification systems

We’ve talked about it time and time again. Automatic Identification Systems (AIS) are valuable tools in the shipping industry. But while AIS systems and the data they produce are helpful, they have some limitations and drawbacks to be aware of.

One of the most significant AIS limitations is how easy they are to manipulate, and they can simply be switched off when a ship’s operator wants to operate undetected. But that’s not all.

Below, we look more at the advantages and limitations of AIS in shipping and talk about some of the solutions to help bridge those AIS gaps.

But first, here's an infographic giving a high-level overview of the advantages and disadvantages of AIS.

advantages and limitations of AIS infographic

Advantages of AIS

Let’s start by taking a look at the biggest advantages of AIS.

Tracking and Collision Avoidance

AIS systems were first developed as a tool to help ships avoid collisions at sea. These systems send and receive location data (and other data) with AIS transponders to nearby vessels and coastal authorities.

As long as the system is activated, the system will send and receive data. So, regardless of weather or other obstacles like ships, islands, or land bends, an operator can know what lies around the corner before it’s in sight. It also works in the dark, so it provides enhanced safety during the night.

Long-Term Data Storage

AIS tracking data is also collected by satellites, which is ultimately relayed to their associated ground stations, where the data is cataloged and stored. This data can be referenced to help verify a ship's movements, location, or activity, and while certain data may be proprietary in some cases, most Automatic Identification System data is considered public domain.

Largely Unaffected by Inclement Weather

Another strong advantage of AIS is that these systems continue to work in the rain, under cloud cover, or throughout other severe weather conditions, making it a great alternative and solution that solves some of the challenges associated with radar.

Automation and Ease of Use

AIS systems are simple to use. Since these systems ping and collect location and other vessel data automatically, there really isn’t any legwork that goes into using it in real time. However, AIS systems do require some manual pre-journey input - although limited.

Limitations of AIS (AIS Gaps)

While AIS is undoubtedly useful, there are some severe AIS limitations that must be considered.

Potentially Inaccurate Information

The potential of receiving inaccurate AIS data from a ship is among the biggest limitations of AIS systems. At times, ships will show incorrect destinations or, at some points, might not even appear on AIS at all. This is typically due to a manual error - maybe a case where an entry was input incorrectly or the operator forgot to make an update after a long anchor period.

Still, most crews update their AIS systems manually as part of a pre-departure task list, so it’s not always a problem. The issue is that trusting AIS 100% for tracking is not as cut-and-dry as we would like it to be.

Easily Manipulated

Some would argue that since AIS tracking data is so easy to manipulate, it should only be used alongside other tools to monitor, track, and investigate suspicious vessels or events.

Another limitation of AIS and the easiest way to manipulate AIS tracking data is to simply turn off the transponder. Once the system is switched off, it no longer sends or receives AIS data, allowing vessels to operate as dark ships. While this method of manipulation is obvious and clearly signals the potential of nefarious activity, it is a commonly used tactic for quick calls to port or STS transfers.

Another method of AIS manipulation is called “spoofing.”

AIS spoofing is a technique used by ships that, rather than turning off their AIS transponders and operating in the dark, broadcast false signals and location data to mask their actual movements. This is beneficial for ships looking to offload things like sanctioned cargo, as they can make a transfer or call to port before the manipulation event is identified.

Data Interpretation Challenges

Pinging and receiving location data and other identification data is great, but the user needs to know how to assess and interpret the data accurately to be truly useful. And knowing that Automatic Identification System data is sometimes inaccurate or even manipulated, it can be tricky to assess specific data or events correctly. In these cases, visually plotting the data can help reduce the risk of misinterpretation.

How to Solve the Most Common AIS Manipulation Challenges

Verify AIS Gaps with RF and Space-Based Tracking Data

Tracking vessels using AIS tracking data can be a good way to understand movements and intentions, but without other technology to accompany it, it has too many AIS gaps to remain reliable.

Radio Frequency (RF) data, sometimes called radar emissions data, is data from radio waves emitted from machinery, ships, cars, and other technology. Every vessel operating at sea emits a significant amount of RF data, which can be used for geolocation validation and to investigate an AIS gap. Today, companies with the appropriate resources offer numerous geolocation validation services. These companies typically specialize in these services and commonly use small satellite constellations to record vessel movements. Since RF data reliably shows ship movement in an area of the ocean, it can be paired and analyzed alongside AIS data to verify vessel location and journeys. This technology fills a significant gap in the capabilities of AIS tracking, which is particularly useful in monitoring and mitigating things like IUU fishing, sanctions avoidance, and more.

Pairing Earth Observation Data and Earth Intelligence Data for Vessel Monitoring

Earth observation data and Earth intelligence data can also be used to verify the quality of the AIS data a ship is transmitting, or validate an AIS gap.

When a vessel is operating as a dark vessel or spoofing its AIS position, specific parameters can flag Automatic Identification System data as invalid. This is typically done through satellite monitoring from companies that offer AIS solutions like Spire Global or Planet Federal, each of which offers services to help identify vessels acting suspiciously.

AIS data providers like those listed above are a great partner in managing and securing the maritime domain, so further investigation should be executed by those with stake in the sector.

These services allow maritime authorities to track vessel activity in real time, which is logged and filed for future reference. From there, if a vessel is suspected of acting illicitly, those with interests can search back in time and see when and where an AIS gap or inconsistency has occurred - allowing for more informed management and enforcement.

1,632 views0 comments

Recent Posts

See All


bottom of page