News Highlights:
- We have achieved the world's first successful lightning triggering and guiding using a drone by harnessing electric field fluctuations.
- We developed and validated a lightning protection cage design that prevents malfunction or damage even when the drone is struck directly by lightning. This design can also be implemented on commercial drones.
- In the future, we aim to protect cities and infrastructure with "lightning drones," working toward a society free from lightning-related damage.
TOKYO - April 18, 2025 - NTT Corporation (Headquarters: Chiyoda, Tokyo; President and CEO: Akira Shimada; hereinafter "NTT") has become the first in the world to successfully trigger and guide lightning using a drone. This experiment also demonstrated, under natural lightning conditions, the effectiveness of both the drone's lightning protection technology and the electric field-based lightning triggering method. These results are expected to contribute to further research on the still-mysterious mechanisms of lightning and to help reduce lightning-related damage to cities and people.
Background
Lightning strikes are one of the most destructive natural phenomena affecting human society. While the NTT Group has implemented various lightning protection measures for critical infrastructure—including telecommunications facilities—lightning-related damage remains a persistent issue. In Japan alone, the estimated annual cost of lightning damage ranges from 100 to 200 billion yen1. Building on its long-standing expertise in protecting communications equipment from lightning, NTT is now working to advance this technology further, with the aim of eliminating lightning strikes on infrastructure and urban areas altogether.
Traditionally, lightning protection has relied heavily on lightning rods. However, their protective range is limited, and in some cases—such as wind turbines or outdoor event venues—it may not be feasible to install them. At NTT, we are exploring the use of rapidly advancing drone technology to create a new approach: "drone-triggered lightning"2. This method involves flying drones into optimal positions beneath thunderclouds to actively trigger lightning strikes, and then guiding the discharge safely away from vulnerable areas.
Overview and Key Findings of the Experiment
From December 2024 to January 2025, a lightning-triggering experiment using drones was conducted at an elevation of 900 meters in a mountainous area of Hamada City, Shimane Prefecture. In this experiment, a device called a field mill3 was used to monitor the electric field at ground level. When the electric field strength increased due to the approach of a thundercloud, a drone equipped with a custom-designed lightning protection cage was launched to attempt lightning triggering (Figure 1).
Figure 1 Lightning Protection Drone
On December 13, 2024, during the approach of a thundercloud, the electric field strength observed by the field mill increased. At that moment, a drone equipped with a conductive wire was flown to an altitude of 300 meters. The drone was then electrically connected to the ground via a switch installed on the ground (Figure 2). As a result, a large current was observed flowing through the wire, accompanied by a significant change in the surrounding electric field strength (Figure 3).
Just before the lightning strike, it was confirmed that a voltage of over 2000 volts had developed between the wire and the ground. This rapid increase in local electric field strength triggered a lightning strike directed at the drone. This marks the first successful case in the world of triggering lightning using a drone.
At the moment of the strike, a loud cracking sound was heard, a flash was observed at the winch, and partial melting occurred in the drone's lightning protection cage (Figure 4). However, the drone equipped with the protective cage continued to fly stably even after the lightning strike.
Figure 2 Experimental Setup for Drone-Based Lightning Triggering
Figure 3 Observed Waveforms During Lightning Triggering
Figure 4 Flash Emission from the Winch During Lightning Triggering
Technical Highlights
To successfully trigger lightning using a drone, the drone must remain operational even after being struck. Moreover, simply flying a drone under a thundercloud is not sufficient to attract lightning; an active triggering method is required. To address these challenges, we proposed and demonstrated the following two key technologies:
(1) Lightning Protection Technology for Drones
We developed a lightning protection cage design that prevents malfunction or damage even if the drone is directly struck by lightning. This cage, which can be mounted on commercially available drones, is made of conductive metal and functions as a shield. It redirects the high current from the lightning strike away from the drone's internal components, preventing it from flowing through the drone itself. Additionally, the cage is designed to distribute the lightning current radially, which cancels out the strong magnetic fields generated by the current and minimizes electromagnetic interference with the drone (Figure 5).
Furthermore, we conducted artificial lightning tests on drones equipped with the lightning protection cage. The results showed that the system withstood artificial strikes of up to 150 kA—five times greater than the average natural lightning strike—without any malfunction or damage, covering over 98% of naturally occurring lightning conditions.
Figure 5 Lightning Protection Design for High Current and Strong Magnetic Fields
(2) Electric Field–Based Lightning Triggering Technology
To actively trigger lightning, we devised a method in which a conductive wire connects the drone to the ground, with a high-voltage switch installed on the ground side. By operating this switch at the optimal moment, we can rapidly change the electric field around the drone. This sharp increase in local electric field strength encourages a lightning discharge to occur toward the drone (Figure 6).
Figure 6 Principle of Electric Field–Based Lightning Triggering Technology
Outlook
NTT aims to protect cities and people from lightning damage by flying drones—designed to withstand direct lightning strikes—to accurately predict lightning-prone locations, actively trigger strikes, and safely guide them away. To improve the success rate of drone-based lightning triggering, we will continue to advance research and development in two key areas: high-precision lightning location prediction and a deeper understanding of lightning mechanisms. In addition, we aim to not only trigger and control lightning, but also to harness its energy. Future efforts will focus on developing technologies for capturing and storing lightning energy for potential use (Figure 7).
Figure 7 NTT's Vision: Protecting Cities from Lightning and Harnessing Its Energy Using Drones
[Glossary]
1The Institute of Electrical Engineers of Japan, Technical Report No. 902, 2002.
2Lightning triggering: The active process of "initiating" lightning and "guiding" it safely to a target location.
3Field mill: A device used to measure atmospheric electric fields.
About NTT
NTT contributes to a sustainable society through the power of innovation. We are a leading global technology company providing services to consumers and businesses as a mobile operator, infrastructure, networks, applications, and consulting provider. Our offerings include digital business consulting, managed application services, workplace and cloud solutions, data center and edge computing, all supported by our deep global industry expertise. We are over $92B in revenue and 330,000 employees, with $3.6B in annual R&D investments. Our operations span across 80+ countries and regions, allowing us to serve clients in over 190 of them. We serve over 75% of Fortune Global 100 companies, thousands of other enterprise and government clients and millions of consumers.