Tokyo Drone Catching: How It Works & Rules
- Max range at 10 min
- m
- Result
- Flight time of interceptor
- 10 min
- You entered
- Distance to target drone
- 100 m
- You entered
Yes, Tokyo uses drones to catch other drones. The Tokyo Metropolitan Police deploy interceptor drones equipped with nets to capture unauthorized or rogue drones, a practice that has been in place since 2016. This article explains how the system works, why it exists, and what the real-world limitations are.
Formula
The calculator estimates how long an interceptor drone takes to reach a target and how far it can fly given its flight time and speed. The formula for time is time = distance / speed, where speed is entered in km/h but converted to m/min. The formula for range is range = flight time × speed, with flight time in minutes and speed in m/min.
Variables:
- t – flight time of the interceptor (minutes)
- d – distance to the target drone (meters)
- speed – assumed 10 km/h (typical for a small quadcopter)
Worked Example
Using the default values: t = 10 min, d = 100 m. Speed = 10 km/h = 10,000 m/h = 166.67 m/min.
Time to reach = 100 / 166.67 = 0.60 min (about 36 seconds).
Max range = 10 × 166.67 = 1,667 m.
So the interceptor can reach a drone 100 m away in about 36 seconds, and can fly up to 1.67 km before battery runs out.
Why Tokyo Uses Drone-Catching Drones
Tokyo is one of the most densely populated cities in the world, and its airspace is crowded with buildings, power lines, and people. A rogue drone – whether from a hobbyist, a prankster, or a malicious actor – poses a serious risk of collision, injury, or disruption. The Tokyo Metropolitan Police began deploying interceptor drones in 2016 after a drone carrying radioactive material was found on the prime minister’s office roof in 2015. That incident highlighted the need for a rapid, safe response to unauthorized drones.
The chosen solution was not to shoot drones down – bullets would fall back to the ground and could hurt people – but to catch them with nets. A larger drone carries a net underneath, flies above the rogue drone, and drops the net to ensnare its propellers. The captured drone is then brought to the ground, often dangling beneath the interceptor.
How the Interceptor Drones Work
The interceptor drones used by Tokyo police are essentially custom-built quadcopters, larger than typical consumer models. They carry a net that is about 2 meters by 3 meters, with weights at the corners to help it drop quickly. The procedure is:
- The police spot the rogue drone via radar or visual observation.
- An interceptor drone is launched from a nearby police vehicle or station.
- The pilot flies the interceptor above the rogue drone, aligning the net over it.
- The net is released, enveloping the rogue drone and tangling its rotors.
- The interceptor then descends, carrying the captured drone to a safe location.
This method avoids shooting, which could cause the rogue drone to crash unpredictably. It also avoids jamming signals, which could make the drone fly erratically. The net approach is considered safer for bystanders and property.
Legal and Operational Context
Japan’s aviation law (the Civil Aeronautics Act) and the Small Unmanned Aircraft Act restrict drone flights over crowded areas, near airports, and above 150 meters. The police have the authority to intercept drones that violate these rules. However, the use of interceptor drones is not a routine patrol activity; it is a response to specific incidents. The police typically warn the operator first if possible, and interception is a last resort.
Since the 2016 deployment, there have been few publicly reported interceptions in Tokyo. The system is more a deterrent than a frequently used tool. The Japanese government has also invested in other counter-drone measures, such as jamming devices and drone-detection radar, but the net-carrying interceptor remains the most visible.
Common Misconceptions
One common misconception is that Tokyo police shoot down rogue drones with guns. In fact, they use nets to avoid collateral damage. Another is that the interceptor drones are autonomous; they are manually piloted by trained officers. The net drop requires precise timing and a skilled pilot, especially in windy conditions.
Another misunderstanding is that this technology is unique to Tokyo. Other countries, including the Netherlands and the UK, have experimented with net-carrying drones for counter-drone operations. However, Tokyo is often cited as a pioneer because of its early adoption and the high-profile incident that prompted it.
Limitations and Challenges
Interceptor drones have several limitations. They can only fly for about 10–15 minutes, so they must be launched quickly. They are also vulnerable to wind and rain, which can make net deployment inaccurate. If the rogue drone is flying very fast or very high, the interceptor may not be able to catch up. Additionally, the net can only capture one drone at a time, so a swarm attack would overwhelm the system.
Another challenge is legal: the interceptor drone itself is a drone flying in restricted airspace, so it must be operated under special permission. The police are exempt from some restrictions, but they still must avoid endangering people on the ground.
Alternatives to Net-Catching
Other counter-drone methods include:
- Radio jamming: Disrupts the drone’s control signal, forcing it to land or return home. This is effective but can cause the drone to crash unpredictably.
- GPS spoofing: Sends false GPS signals to trick the drone into flying elsewhere. This is complex and may not work on drones with advanced navigation.
- Kinetic projectiles: Shotguns or nets fired from the ground. These have limited range and accuracy.
- Laser weapons: Can disable drones by burning their components, but are expensive and not widely deployed.
- Trained eagles: Some police forces have trained birds to catch drones, but this is experimental and risky for the bird.
Tokyo’s net-carrying interceptor is a middle ground: it is reusable, relatively safe, and does not require specialized ground equipment.
Frequently Asked Questions
Can I fly a drone in Tokyo?
Yes, but only in designated areas and below 150 meters, and you must avoid crowded places, airports, and government buildings. You also need to register your drone if it weighs over 100 grams. Always check local rules before flying.
What happens if my drone is caught by police?
You will likely be questioned by police, and your drone may be confiscated as evidence. You could face fines or even criminal charges if you violated aviation law. The police will typically return your drone after the investigation, but that is not guaranteed.
How fast do interceptor drones fly?
Most consumer quadcopters fly at 30–60 km/h, but police interceptor drones are often slower, around 10–20 km/h, because they carry a net and need stability. They are not designed for high-speed chases; they are designed for precision capture.
Are interceptor drones used outside Tokyo?
Yes, other Japanese cities and some countries have adopted similar systems. However, Tokyo is the most famous because of its dense population and the 2015 incident. Many police forces now use a combination of detection radar, jammers, and net-carrying drones.
Is it legal for police to fly drones over Tokyo?
Yes, police are exempt from many drone restrictions when performing official duties. They must still follow safety protocols and avoid endangering people. The exact rules are outlined in Japan’s Small Unmanned Aircraft Act.