Tethered drones: the 24-hour eye in the sky (and when you actually need one)

Battery anxiety, solved. If your mission needs a stable camera or comms node that can stay up all day and all night, tethered drones fix the core limitation of normal aircraft by sending continuous power up a slim cable and, in many systems, returning data over fibre to the ground. That is how public safety teams keep a live aerial view running for 24 hours or more without a single battery swap.

What are tethered drones?

Tethered drones are multirotor aircraft connected to a ground station by a slender micro‑tether that carries power and, often, data. The tether makes the aircraft behave like a powered, mobile mast that you can reposition quickly and elevate within seconds, which is why you will see these systems at incidents, events, infrastructure sites, and temporary checkpoints where a continuous overhead view is valuable. In Australia they are still considered remotely piloted aircraft, so the usual responsibilities around safe operation, airspace and people on the ground remain in play.

Is a tethered drone still a drone? Yes. The presence of a cable does not turn it into a balloon or a kite. It remains a drone, operated by a pilot or an approved automated workflow, and it must meet the same expectations for airspace separation, weather limits and site risk controls. In short, it is a normal drone that draws its power, and sometimes its data, through a cable instead of relying only on onboard batteries and radio links.

How tethered drones work

The micro‑tether looks like a thin cable, yet it carries impressive power and data. A ground power station converts vehicle alternator or generator output to the voltage your aircraft needs, then sends it up the tether. Onboard, a compact power module replaces or supplements the flight batteries, which removes the main endurance limit of normal drones. Many modern tethers include fibre optic strands in the same jacket, giving a reliable, low‑latency data path that is resilient to congested radio environments. Where fibre is not used, systems may send data via broadband over the power conductors or maintain standard RF links as a fallback.

Launch is usually push‑button simple. A typical workflow is: park, secure the base, set a small safety cordon, connect the air module, press launch, and let the automated winch manage tension while the aircraft climbs to the preset height. That simplicity is the point. It lets a crew get a camera into the air within seconds and keep it there for an entire shift with very little pilot workload.

How long can a tethered drone fly?

With power from a vehicle, building mains or a generator, endurance is measured in hours rather than minutes. Many suppliers describe 24‑hour operation under typical payloads. The exact duration depends on your power source, payload draw, ambient temperature and cable losses, yet the practical outcome is the same. You can plan around hours of uninterrupted coverage and predictable shift changes instead of a constant cycle of battery swaps. For teams that have ever missed the key moment because a drone had to land for batteries, this is the killer feature.

What is the altitude and range of tethered drones?

Altitude is a mix of technical limits and local rules. Tether lengths of around 70 m to 100 m are common in compact stations, which sits comfortably under Australia’s standard ceiling of 120 m AGL for most operations. In practice, many teams choose 45 to 100 m for stable overwatch and clear sight lines, keeping within the tether’s rated length and any site‑specific approvals. Taller options exist in specialist systems, though portability and wind loading become the trade‑off.

Range is not like a free‑flying drone. The aircraft’s movement is constrained by the tether length and a safe operating bubble around the base. Think of it as a rapidly deployable mast that you reposition by moving the ground station rather than by flying long distances. For most overwatch jobs this is ideal, since you want a steady eye in a known small volume of airspace rather than a roving camera.

What is the difference between tethered and untethered drones?

The differences come down to endurance, mobility and spectrum. A normal drone uses onboard batteries, so endurance is typically 20 to 45 minutes with payload. It can roam freely across a site, but every extra minute is borrowed from the battery. A tethered system trades roaming range for persistent height and power. It can sit over a scene for hours, stream data over a shielded fibre link, and avoid the throughput limits or interference issues that affect some radio links. That is why you will find tethered drone systems outside stadiums, beside construction gates and at incident command vehicles that need a stable elevated viewpoint all day.

When you actually need tethered drones

Disaster connectivity. After storms, floods or bushfires, telcos and emergency managers have used tethered aircraft as flying small cells to restore coverage quickly while damaged ground infrastructure is repaired. A small cell payload lifted to tens of metres can provide a useful service footprint for communities and responders. The tether keeps it powered and precisely located for as long as required.

Public safety overwatch. Fire and police departments worldwide use actively tethered systems to put an eye over a cordon within seconds. Continuous RGB and thermal video assists with perimeter safety, crowd flow and hotspot detection at night. The long‑duration view is the differentiator, since nothing needs to land for batteries and the perspective stays consistent for video review.

Events and venues. For stadiums, festivals and parades, a tethered drone provides a stable 70 to 100 m aerial camera that can sit in a safe box and watch entrances, queues and choke points. With the fibre option, your operations room gets a hard‑wired feed for recording, analytics and distribution to multiple screens without saturating local RF.

Construction and inspection. On large sites, a mobile mast that goes up in under five minutes is useful for daily logistics, crane movements and gate management. It also avoids delays and constraints associated with fixed masts or cherry pickers for many line‑of‑sight observation tasks. Some users rotate a tethered unit between gates through the day to match traffic peaks.

Broadcast and production. A persistent, high‑angle shot that never needs a battery change is a dream for time‑lapses, arrival sequences and crowd‑safe establishing shots. A tethered configuration can feed SDI or IP video into a truck while the free‑flying camera drone captures cutaways and tracking shots.

Types of tethered drone systems

Purpose‑built, actively tethered platforms. These are designed from the ground up for constant overwatch, with one‑button launch, automated winch control and ruggedised power electronics. Public safety models focus on portability and minimal training. Defence‑oriented versions lift heavier payloads from vehicle mounts and emphasise survivability and jam resistance.

Conversion kits for normal drones. If you already operate commercial DJI aircraft, you can add a power‑tether station and a small air module that integrates with the drone’s power bus. This is a common path for teams that already fly DJI in production. The appeal is obvious. You keep your existing pilot training, spares and gimbal cameras, then extend endurance dramatically for static tasks.

Telecom‑specific payloads. Some builds combine a tether station with a small cell or eFemto in the air. These special payloads are tied to mobile operators and integrators, and they shine during disaster response and temporary capacity boosts for major events.

Key components at a glance

Component	What it does	What to look for
Ground power station	Converts generator or vehicle power to stable DC sent up the tether	Peak output in watts, IP rating, portability, automatic winch control, swappable reels
Micro‑tether cable	Carries power and often data between base and aircraft	Length 70 m to 100 m, fibre optic option, abrasion resistance, weather sealing
Air module	Interfaces tether power to the drone and manages battery fallback	Drone compatibility, mass, heat management, redundant comms paths
Software or app	Controls winch tension, monitors power, integrates the tethered drone app with your flight app	Telemetry overlays, alarm thresholds, remote control from a command post, audit logs

Modern stations offer features like automated winch tensioning and dual‑comms, where fibre and broadband over powerline operate in parallel for data redundancy. These details matter if your site has heavy RF congestion or multiple competing radio systems.

Advantages of tethered drones

Endurance and predictability. Continuous power means continuous coverage. Crews can plan around hours, not minutes, which reduces staffing for battery swaps and eliminates gaps in recorded footage. That single advantage settles the endurance question for most use cases.

Stable comms. Fibre data links inside the tether give you a direct pipe that is largely immune to local interference. Where standard radio control links can get saturated at crowded events, fibre keeps throughput and latency consistent. If fibre is not available, a powerline modem can maintain a robust link for command and telemetry.

Safety and control. The aircraft is leashed to a known volume of airspace, with software managing cable tension. Many systems include a battery in the air module so the drone can land safely if ground power is lost. A bright, visible tether and well‑placed cones reduce the chance of anyone wandering into the line.

Compliance support. Because the aircraft sits near a fixed point, risk assessments and site plans are often simpler than for roving free‑flight. That does not remove regulatory duties, yet it can make crowd and vehicle separation planning more straightforward for certain jobs where a set position is acceptable.

Limitations and trade‑offs to consider

• Mobility. You give up long‑range roaming. If the task involves tracking moving subjects across a wide area, a free‑flying aircraft is still required.
• Line management. The tether is live infrastructure. Plan routing carefully, keep it clear of vehicles and the public, and brief all crews. Add lighting for night work.
• Wind loading. A long cable in strong wind adds drag and sway. Choose realistic heights for the day’s conditions and use weather forecasts to plan shifts.
• Obstructions. Cables, poles and trees become genuine hazards when you have a line attached to the aircraft. Site walks and clear launch boxes matter.
• Power logistics. Generators, inverters and alternators need fuel and cooling. Budget for the full power chain, not just the tether station.

Weather and operating limits

Tethered drones handle light to moderate winds well when flown at sensible heights. As wind increases, the cable behaves like a long, thin windsock and places continuous load on the aircraft and winch. Most teams publish conservative wind limits for rooftop or vehicle‑mounted use and a slightly higher limit when operating from open ground. Rain resistance depends on the IP rating of the ground unit and air module. Plan for safe recovery if gusts exceed limits, which can be as simple as winching down to a lower height until conditions settle.

Set‑up workflow that busy crews can trust

1. Pick a launch site with clear air above and a clean cable path to the aircraft.
2. Park safely, chock wheels if on a slope, and establish a small exclusion zone with cones or tape.
3. Power the station, confirm voltage and temperature readings are nominal.
4. Attach the air module, check quick‑release fittings and strain relief, then perform a controls check.
5. Press launch and allow the winch to pay out to the preset height. Set a height limit matching the site plan.
6. Route the cable away from feet and tyres. Add a visual marker on the line if operating near foot traffic.
7. Monitor power draw, tether tension and video health from the app, and log key events for the job record.
8. On recovery, winch down steadily, disconnect, coil any loose line and complete a quick tether inspection.

Costs and budgeting

Pricing varies widely because configurations do too. Budget lines typically include the station itself, one or two tether reels, the air module for your aircraft, a transport case, and optional extras such as fibre data, roof mounts and remote control panels. Add a power solution, whether that is a vehicle alternator upgrade, a pure sine wave inverter, or a compact generator. Consumables include spare tether sections, strain‑relief parts and filters for any onboard cooling. Service plans cover winch calibration, bearings and power electronics. A tethered drone kit that converts an existing platform can be more economical than a purpose‑built system if you already own compatible drones, though you should account for downtime during integration and testing. Total cost of ownership is influenced by duty cycle, cable replacement intervals, environmental exposure, and the level of redundancy you build into comms and power.

Military and government users

The phrase Tethered drone military usually refers to persistent ISR over a base, border or convoy. Vehicle‑mounted masts can loft electro‑optical, infrared, comms relay and signals payloads to useful heights within a few minutes. Although these platforms target defence and public safety, design ideas like robust winches, cable management, and jam‑resistant command links have influenced commercial models and raised reliability across the board. In humanitarian operations, a similar setup can serve as a temporary relay or overwatch node to coordinate convoys and protect field hospitals.

Answers to common questions

• What are tethered drones? Multirotors fed by a ground power station through a micro‑tether, often with fibre data inside the same cable. This is why they can operate continuously.
• How do tethered drones work? Continuous power goes up the cable, data comes down by fibre or powerline comms, a smart winch manages tension, and a small air module powers the aircraft and handles safe landing if the base loses power.
• What is the difference between a tethered drone and a normal drone? Endurance versus mobility. Tethered wins for persistence and interference‑resistant links, normal wins for roaming, mapping and tracking tasks.
• What is the range of a tethered drone? Effectively the tether length and a safe radius around the base, commonly 70 m or 100 m vertical, with lateral movement kept to a small box.
• What is the altitude of tethered drones? Usually set by the tether length and local rules. In Australia the standard maximum for many operations is 120 m AGL unless you have an approval.
• How long can a tethered drone fly? Hours, often a full day or more when powered from a vehicle or generator, provided cooling and payload draw are within limits.
• Are fibre optic drones tethered? Yes. When people use this phrase they usually mean a tethered setup that uses fibre in the cable for the data link.
• Tethered drone DJI. Commonly refers to conversion kits and air modules that integrate with DJI Matrice series and similar platforms.
• Tethered drone uses. Disaster connectivity, public safety overwatch, traffic and crowd management, construction logistics, television and events, and temporary security posts.
• Tethered drone systems. The combined ground station, cable and air module, sold either as purpose‑built platforms or as upgrade kits for existing aircraft.
• Tethered drone app. The companion software that runs the station and winch, shows power and tension, and integrates with your flight control app for height limits and alarms.
• Tethered drone kit. A bundle that converts a standard drone into a tethered unit, typically including the station, a reel, the air module and cables.

Choosing between options

If your team already operates DJI Matrice aircraft, a conversion path keeps training and spares simple. Look for air modules certified for your exact model and battery generation, and check the vendor’s compatibility notes. If you want the fastest deployment in a single‑operator workflow, consider a purpose‑built unit with one‑button launch and an integrated roof or boot mount, especially if your crews are used to CCTV rather than RC. Telco and command‑post builds are specialist work, typically done in partnership with carriers and systems integrators.

Risk and practicalities

A micro‑tether is not a benign shoelace. Treat it as live infrastructure. Plan where the cable runs, stake the base securely, and separate the public from the line. Keep the cable out of vehicle routes and pedestrian flow, especially at night. Most stations include alarms for power, tension and thermal limits. Build those into your SOPs with clear abort and recovery actions. Add simple touches like a bright sleeve on the lower section of tether to improve visibility and a safe‑to‑touch sign to discourage curious hands.

A comparison you can share with stakeholders

Scenario	Tethered choice	Untethered choice	Why
Multi‑day festival perimeter	70–100 m tethered overwatch beside the main gates	Backup free‑flight unit for roving safety checks	Persistent eyes at fixed points, roving coverage fills blind spots
Storm response with mobile coverage outage	Tethered small cell platform with fibre data to base	Free‑flight mapping missions after comms are restored	Keep people connected first, then inspect and map
Busy construction gate and crane moves	Portable tether station on a ute with roof mount	Spot free‑flight shots for progress stills	Continuous situational awareness, minimal staffing
TV event with predictable arrivals	Tethered high‑angle establishing shot feeding the OB truck	Free‑flying tracking drone for dynamic cutaways	Unbroken master shot plus dynamic inserts

Final checklist before you buy

• Confirm compatibility with your aircraft and payload, especially for DJI Matrice generations and battery types.
• Pick a tether length that suits your sites. Seventy metres improves portability, one hundred metres improves vantage. Both sit within Australia’s 120 m default ceiling for many jobs.
• Decide if you need the fibre optic option for congested RF environments or long high‑bitrate streams.
• Plan power. Vehicle alternator, inverter or generator sizing is a real design choice for day‑long operation. Check cooling and ventilation for hot Australian summers.
• Write SOPs for tether handling, exclusion zones and cable recovery, then train to them. Include night procedures with lighting and reflective markers.
• Think through data pathways. If you intend to broadcast or analyse in real time, design for reliable backhaul from the ground station to your control room.

Quick glossary in plain English

Power‑over‑tether. The ground station sends DC power up the cable to the aircraft, enabling hours of flight without swapping batteries.

Fibre data link. Glass fibres inside the tether carry command and video with low latency and high immunity to interference, ideal for stadiums and disaster zones where RF is crowded or unreliable.

Tethered drone systems. The combined ground station, cable and air module, sometimes sold as a tethered drone kit for your existing platform.

The bottom line

If your mission is more about being there than flying around, tethered drones are your 24‑hour eye in the sky. They are ideal when persistence, reliable bandwidth and predictable safety footprints matter more than long range. For Australia, keep the 120 m rule, local airspace considerations and robust tether procedures front of mind. Get those right, and you have a simple, repeatable way to give your team stable aerial intelligence whenever they need it.