Turnstone, a new weapon in open source research

Bellingcat, an international media outlet specializing in investigative reporting, has unveiled ‘Turnstone’, a new tool for visualizing and analyzing aviation data. The tool is designed to detect unusual patterns and identify historical trends in global flight data of 100,000 flights per day.

Turnstone operates based on Automatic Dependent Surveillance Broadcasting (ADS-B) data. ADS-B is a technology installed on most civil aircraft, and transmits the aircraft's identification information, model, exact location, speed, and altitude in real time. However, there are differences in regulations by country, and in some cases, military aircraft are not sent.

Differences from existing tools

Existing flight tracking websites such as Flightradar24 or ADS-B Exchange only provide historical data for specific time periods or individual aircraft. On the other hand, Turnstone aggregates data from multiple aircraft over a long period of time and provides the ability to search two areas of interest simultaneously.

Users can filter data by various parameters, including aircraft type, geographic area, and flight direction. This will allow open source investigators to more accurately determine the context in which specific aircraft movements occurred.

Real life example: Signs of anomalies detected in a US tanker prior to the Iranian airstrike

There is a representative example that shows the potential use of Turnstone. On February 28, 2026, the United States and Israel carried out a joint airstrike against Iran, reportedly killing more than 1,000 people, including Iranian leadership. This marked a dramatic increase in tensions following the bombing of three Iranian nuclear facilities in June 2025.

Bellingcat used Turnstone to analyze aerial data prior to the two airstrikes. As a result of setting the North Atlantic region as the area of ​​interest, filtering the aircraft type as tanker and the flight direction as east, a pattern of mass movement of US military aerial refueling tankers such as KC-135 and KC-46A across the Atlantic toward Iran was detected. Aerial refueling tankers are essential aircraft for long-distance combat missions, and these abnormal signs can be interpreted as a sign of a large-scale military operation.

As a result of the search, more than 40,000 aircraft location data met the filter criteria, and it was also possible to extract only US tankers by entering "United States".

When did this trend start? The Rise of Open Source Intelligence

Open source intelligence (OSINT) began to receive international attention following the investigation into the downing of a Ukrainian-Malaysian plane in 2014. Bellingcat proved the Russian military's intervention by analyzing social media posts and satellite photos at the time, and has since established itself as a representative player in OSINT.

After Russia's full-scale invasion of Ukraine in 2022, the importance of OSINT has become more prominent. Ordinary citizens have also begun to play the role of ‘citizen information analysts’ who analyze military trends by combining publicly available aviation data, satellite images, and SNS information. The release of Turnstone is the latest step in the evolution of these OSINT tools.

Tool limitations and approaches

Bellingcat also specified some limitations of Turnstone. Claude Sonnet 4.0, a large-scale language model (LLM), was used to classify aircraft categories, but incorrect classification may occur due to the nature of LLM. Additionally, ownership data may be out of date and data may not be available for newly registered aircraft.

Turnstone's source code is open to the public on Bellingcat GitHub, so anyone can self-host it. A web-based version also exists, but access is granted selectively to journalists and academic researchers due to data hosting and processing costs. Priority will be given to researchers conducting open source research that aligns with Bellingcat's goals.

Future outlook [AI analysis]

The emergence of tools like Turnstone will likely further accelerate the democratization of open source research. Aviation data analysis, which was previously only accessible to intelligence agencies, is now available to journalists, researchers, and civic groups.

This has two-sided implications. Positively, it can contribute to monitoring power and enhancing transparency. By detecting signs of military operations or covert activities in advance, the media and civil society can conduct independent verification rather than relying solely on government announcements.

On the other hand, the proliferation of these tools may raise concerns from a national security perspective. Maintaining the security of military operations may become difficult, and the possibility of malicious actors using the same tools in reverse cannot be ruled out.

In the future, OSINT tools are expected to become more sophisticated through combination with artificial intelligence (AI) technology. It is highly likely that the ability to automatically detect patterns in large amounts of data and provide real-time notification of abnormalities will be strengthened. However, there are still challenges to be solved, such as accuracy issues in LLM-based classification, data access costs, and establishment of ethical use guidelines.