TL;DR: Drones inspect confined spaces by flying a collision-tolerant, caged UAV into a tank, silo, duct, vessel or bin and capturing high-resolution imagery, 3D point clouds or thermal data without sending a person inside. On Australian sites this removes the confined-space entry — the single most heavily permitted, highest-risk task in any shutdown — while delivering condition and dimensional data referenced to the asset, captured in hours rather than the days a manned entry and access build demand.
Key takeaways
- A confined-space drone inspection eliminates human entry, removing the permit chain, standby personnel, gas testing cycles and rescue plan that make manned entry the slowest task in a shutdown.
- The right aircraft is a caged, collision-tolerant indoor UAV — typically a Flyability Elios 3 — not a standard outdoor survey drone; GPS does not work inside steel, so these craft fly on internal sensors and LiDAR-based SLAM.
- The Elios 3 builds a live 3D LiDAR point cloud as it flies, so a vessel or silo is mapped, measured and inspected in a single flight without scaffolding or rope access.
- Inspection by drone keeps the asset off the critical path: a tank that took 2–3 days to scaffold, enter and inspect is covered in a few hours, clawing back shutdown days worth six figures on a major processing train.
- All commercial flights run under CASA Part 101 with a licensed RePL operator on a ReOC, and confined-space drone work still requires a permit and atmospheric controls — the drone removes the person, not the procedure.
- Where millimetre dimensional control is needed, ISS pairs the drone with terrestrial laser scanning (FARO / Leica RTC360) or total-station work referenced to GDA2020/MGA2020 and AHD.
Why confined-space entry is the cost you want to avoid
A confined space — a process tank, a clinker silo, a coal bunker, a ball-mill shell, a boiler, a flue duct, a pressure vessel, a sewer wet well — is the most dangerous place to put a worker on any Australian industrial site. Safe Work Australia consistently records confined-space entry among the leading causes of multiple-fatality workplace incidents, usually from oxygen deficiency, toxic atmosphere or engulfment. Every entry is governed by AS 2865 (Confined spaces) and the WHS confined-space regulations, which means a written entry permit, continuous atmospheric monitoring, a standby person, a documented rescue plan and, frequently, breathing apparatus.
That procedure is correct and non-negotiable — but it is also slow and expensive. Before anyone climbs inside a clinker silo at a cement works or a coal bunker in the Hunter Valley, the asset must be isolated, purged, ventilated, gas-tested and access-built. A surveyor or inspector then works inside a hot, dusty, poorly lit, oxygen-controlled enclosure, frequently from scaffolding or a rope-access rig erected purely to reach the walls and roof. The measurement might take four hours; the entry sequence around it takes two or three days.
This is precisely where drones earn their keep. A confined-space drone inspection reaches the same internal surfaces without putting a person inside. There is no body in the hazard, so the rescue plan, the standby resourcing and the breathing-apparatus logistics shrink dramatically, and the scaffolding or rope-access build is removed entirely. On an operating asset where a single lost production day on a large Pilbara iron-ore train or a Bowen Basin coal-prep plant runs well into six figures, removing days from the entry sequence is the whole point.
The right aircraft: why a caged indoor drone, not a survey drone
The drones that map a stockpile or a tailings dam — a DJI Matrice 350 RTK on RTK/PPK photogrammetry — are useless inside a steel vessel. They navigate by GNSS, and there is no satellite signal inside a tank. They have exposed rotors that snag on internal steelwork, and they need open sky and daylight. Confined-space inspection uses a fundamentally different machine.
The industry-standard tool is the Flyability Elios 3: a compact UAV inside a protective carbon-fibre cage that lets it bump structure and keep flying. It navigates without GPS, using onboard inertial sensors, optical-flow cameras and a Bayesian flight controller, and it carries a survey-grade LiDAR payload that builds a live SLAM point cloud (Simultaneous Localisation and Mapping) as it flies. Add a 4K camera with a powerful onboard lighting array for visual condition, and an optional radiometric thermal sensor for hot spots, and a single aircraft maps, measures and inspects a dark internal void in one flight.
The practical consequences are large. The cage means a pilot can fly close to — and gently against — corroded plate, ladder rungs, internal baffles and roof structure without crashing the aircraft or damaging the asset. The SLAM LiDAR means the inspection is not just imagery: it is a measurable 3D record of the inside of the space, so wall thickness loss, deformation, build-up volume and clearances can be assessed from the data after the flight. No person has entered. No scaffold has been erected.
How a confined-space drone inspection works, step by step
A confined-space drone inspection follows a disciplined sequence. The drone removes the entry, but it does not remove the planning — and shortcutting any of these steps is how a job goes wrong.
Step 1: Scope and atmospheric assessment (before mobilisation)
Define the asset, the internal surfaces of interest and the deliverable: visual condition, a 3D point cloud, build-up volumes, thermal mapping, or a defect register. Confirm the confined-space classification, the isolation state and the atmosphere. Even though no person enters, the operator must understand whether the space is purged, inert or live, because that drives the entry strategy for the aircraft and the permit conditions.
Step 2: Isolation, ventilation and permitting (site, day of)
The site isolates and, where required, ventilates and gas-tests the space to the same standard it would for a manned entry, and issues a confined-space permit covering drone operations. The aircraft is launched from an open access point — a manway, a roof hatch, a inspection port — so the pilot and ground crew remain outside the space at all times. This is the structural advantage: the hazard boundary is the manway, and nobody crosses it.
Step 3: Pre-flight, lighting and flight planning (on the manway)
The pilot powers the Elios 3, confirms the LiDAR and camera feeds on the ground-station tablet, sets the lighting and plans the internal route — typically a systematic sweep of floor, walls and roof so no surface is missed. Battery management is planned around the void size; a large silo or tank is flown in multiple battery cycles.
Step 4: The flight (the few hours that replace days)
The pilot flies the aircraft into the void through the access point and works it methodically around the internal geometry, keeping a live view of every surface on the tablet and letting the LiDAR build the point cloud in real time. The cage allows controlled contact with structure, so tight corners, behind baffles and around internal columns are all reachable. A typical tank or vessel is covered in one to a few flights across a single shift.
Step 5: Processing and reporting (after demobilisation)
The captured imagery and LiDAR data are processed into the agreed deliverables: an inspection report with geo-located defect imagery, a registered 3D point cloud of the internal space, deformation and clearance measurements, build-up or residue volumes, and thermal maps where flown. Where the job needs sub-millimetre dimensional certainty on specific features, those are picked up separately by terrestrial scanning or total station and tied into the same coordinate framework.
What a confined-space drone inspection delivers
The aircraft is only the sensor platform; the value is the processed output. Depending on payload and asset, an ISS confined-space inspection produces:
- High-resolution internal imagery and video — 4K visual condition of walls, roof, floor and internals, lit by the onboard array, with defects located within the space.
- 3D LiDAR point clouds — a measurable, registered record of the internal geometry for clearance, deformation and as-built assessment.
- Defect registers — geo-located images of corrosion, cracking, lining and refractory wear, missing fasteners, weld defects and erosion, positioned on the asset.
- Build-up and residue volumes — quantified material accumulation in silos, bins and hoppers to support cleaning scope and reconciliation.
- Thermal imagery — refractory hot-spot and insulation-failure mapping on furnaces, boilers and kilns where a radiometric payload is flown.
This data does what a torch-and-clipboard manned entry never could: it produces an objective, repeatable, measurable record that the next inspection can be compared against directly.
Accuracy, standards and what to expect
A confined-space drone inspection is excellent for condition assessment, internal geometry and relative measurement, but it is not a metrology instrument. Understanding the accuracy envelope is how you match it to the right job.
| Method | Typical accuracy | Best use inside a confined space |
|---|---|---|
| Caged UAV LiDAR SLAM (Flyability Elios 3) | 20–50 mm relative | Condition, internal mapping, clearance, build-up volume |
| UAV visual photogrammetry (close flight) | mm-relative on defect detail | Corrosion, cracking, weld and lining condition |
| Terrestrial laser scanning (FARO / Leica RTC360) | 1–3 mm | Shell ovality, flange faces, precise as-built geometry |
| Total station (Leica / Trimble) | 2–5 mm | High-precision dimensional control and deformation |
The practical point: for the questions confined-space inspections usually ask — Is this tank corroding? How much build-up is in this silo? Is the refractory failing? Has this duct deformed? — the drone answers them fast, safely and to sufficient accuracy. Where a job demands millimetre dimensional control, such as a mill-shell ovality survey or a flange-face check, ISS scans those features once the space is safe to scan, or picks them up by total station, and references everything to GDA2020/MGA2020 horizontally and AHD vertically so the records are auditable and repeatable.
Two regulatory frameworks govern the work in Australia. CASA Part 101 sets the flight rules: commercial operations require a Remote Pilot Licence (RePL) operator working under a Remotely Piloted Aircraft Operator's Certificate (ReOC). Indoor flight inside an enclosed structure is outside controlled airspace, but the operator still works to their ReOC procedures and the site's drone rules. AS 2865 and the WHS confined-space regulations govern the space itself: the permit, isolation, atmospheric monitoring and rescue arrangements remain in force. The drone removes the person from the hazard; it does not remove the procedure that protects anyone who might still need to approach the manway.
Cost considerations
Confined-space drone inspection costs are modest set against the entry sequence and downtime they remove. The factors below drive the price — all of them dwarfed by a single avoided shutdown day.
| Cost factor | Impact | How to manage it |
|---|---|---|
| Asset size and internal complexity | Larger or more obstructed voids need more flight cycles and processing | Define scope tightly so the flight plan matches the deliverable |
| Payload required | LiDAR and thermal add cost over visual-only inspection | Match the payload to the question, not the most capable option |
| Isolation and ventilation | Purging, inerting and gas testing are site costs, not survey costs | Plan isolation early so the drone is not waiting on a permit |
| Processing depth | A registered point cloud and defect register cost more than raw video | Order only the deliverables that drive your decision |
| Remote mobilisation | FIFO travel to a Pilbara or Bowen Basin site adds cost | Batch multiple assets into one mobilisation |
A typical Australian confined-space drone inspection runs from roughly AUD $2,500 for a single visual tank or vessel inspection to AUD $8,000–$12,000 for a multi-asset LiDAR and thermal programme with full 3D deliverables and defect registers. Set that against six-figure downtime on a major processing train — and against the irreplaceable cost of a confined-space incident — and the return is unarguable.
Common mistakes to avoid
Mistake 1: assuming the drone removes the confined-space procedure
It removes the person, not the permit. The space still needs isolation, atmospheric assessment and a permit, and anyone approaching the manway is still working at the boundary of a confined space. Avoid it: treat the inspection as a confined-space job that happens to use a drone, and keep AS 2865 controls fully in force.
Mistake 2: using the wrong aircraft
A standard outdoor survey drone cannot fly inside a steel vessel — no GPS, no collision tolerance, no internal lighting. Trying it ends in a crashed aircraft inside the asset, which is a far worse problem than the inspection you started with. Avoid it: specify a caged, GPS-denied SLAM platform such as the Elios 3 for any internal void.
Mistake 3: expecting millimetre metrology from the flight
The drone's LiDAR is superb for condition and 20–50 mm relative mapping, but it is not a 1–3 mm scanner. Specifying a drone for a precision shell-ovality or flange survey delivers data that looks impressive and misses tolerance. Avoid it: state the required accuracy up front so the right tool is matched to each feature.
Watch out: the most expensive error is treating "drone" as "no planning". A confined-space inspection still needs scope, isolation, a permit, the right aircraft and the right payload. Get those wrong on a remote FIFO site and you mobilise twice — and a return trip to a Pilbara or Goldfields asset erases every hour the drone was meant to save.
Frequently asked questions
How does a drone actually fly inside a sealed tank with no GPS?
It uses a GPS-denied navigation system. The Flyability Elios 3 flies on internal inertial sensors, optical-flow cameras and a LiDAR-based SLAM controller that maps the space and tracks the aircraft's position within it in real time. The protective cage lets it touch and bounce off internal structure without crashing, so the pilot can work it methodically around the entire internal geometry from outside the manway.
Does using a drone mean we no longer need a confined-space permit?
No. The space remains a confined space under AS 2865 and the WHS regulations, so it still needs isolation, atmospheric assessment, a permit and the relevant controls. What changes is that no person enters the hazard — the pilot and crew stay outside the access point — which removes the in-space rescue exposure and the access build, and dramatically reduces the time and resourcing the entry sequence demands.
Is a confined-space drone inspection accurate enough to base decisions on?
Yes, for the questions these inspections ask. The LiDAR SLAM delivers 20–50 mm relative accuracy for internal mapping, clearance and build-up volumes, and millimetre-relative detail on corrosion, cracking and lining wear when flown close. For sub-millimetre dimensional control on specific features, ISS pairs the drone with a FARO or Leica scanner or a total station referenced to GDA2020/MGA2020 and AHD.
What kinds of confined spaces can be inspected this way?
Process and storage tanks, clinker and grain silos, coal bunkers and bins, hoppers, pressure vessels, boilers and furnaces, flue and HVAC ducts, mill and crusher shells, surge bins, sewer wet wells and pipelines — essentially any enclosed void with an access point large enough to launch the aircraft. ISS confirms suitability during scoping based on the access geometry and internal conditions.
How much downtime does a drone inspection save versus manned entry?
The saving comes from deleting the access build and shrinking the entry sequence. A tank that needs 2–3 days to scaffold, ventilate, enter and inspect is typically covered by drone in a single shift, because the slow items — scaffolding, rope access, in-space rescue standby — are removed. On an operating asset that often means 1–3 shutdown days returned, each worth six figures on a major train.
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Confined-space inspection is the highest-risk, most heavily permitted task on any industrial site — and the one a drone is built to eliminate. By flying a caged, collision-tolerant LiDAR aircraft into a tank, silo, vessel or duct, a confined-space drone inspection captures measurable condition and 3D data without sending a person into the hazard, collapsing a multi-day entry sequence into a few hours of flight while keeping your people safe and your asset producing. Industrial Spatial Solutions runs CASA Part 101 confined-space drone inspections across Australian mines, cement works, ports, power stations and processing plants, pairing aerial capture with laser scanning and total-station work wherever millimetre control is needed. To scope your next inspection and keep people out of the space, call ISS on 0407 057 015 for a fixed-price quote.