TL;DR: A drone inspection survey uses a remotely piloted aircraft carrying high-resolution and zoom cameras to capture close-range imagery of structures and equipment that would otherwise require scaffold, elevated work platforms or rope access. For Australian mining, processing and infrastructure operators it removes people from height and confined spaces, shortens the inspection window from days to hours, and produces a geotagged photographic record that supports condition assessment, defect tracking and AS-aligned reporting. This guide covers what visual inspection involves, the process, equipment, accuracy, when you need it, deliverables, cost factors, and how ISS delivers it.
Key takeaways
- A drone inspection survey replaces working-at-height access on assets such as conveyors, headframes, stacks, tanks, transmission towers and TSF embankments, typically cutting inspection time by 60-80% and eliminating the highest-risk access tasks under the WHS Regulations 2011.
- ISS captures imagery at a ground sampling distance (GSD) of 1-3 mm/pixel on close-range work, resolving hairline cracks, weld toe defects, coating breakdown and corrosion to the level expected of a hands-on visual inspection under AS 3788 and AS 4100.
- Every image is geotagged and, where geometry is required, tied to ground control so defects can be located to within 20-50 mm on a 3D model or orthomosaic for repeat monitoring.
- The work is regulated by CASA under CASR Part 101; ISS operates under a Remote Operator Certificate (ReOC) with licensed RePL pilots, registered aircraft and aviation-endorsed public liability cover.
- Cost is driven by asset height and complexity, airspace and exclusion-zone requirements, image volume, and whether you need raw imagery, a defect register or a fully georeferenced 3D inspection model.
What is visual inspection
A drone visual inspection is the systematic capture of close-range optical imagery of an asset using a UAV, so that an inspector can assess condition without physically touching or accessing the structure. It sits alongside photogrammetry and LiDAR within UAV surveying, but the goal is different: photogrammetry and volumetric work measure geometry, whereas a drone inspection survey is about seeing detail — cracks, corrosion, coating failure, deformation, blocked drainage, missing fasteners, vegetation encroachment and the dozens of other defects that drive maintenance decisions.
The problem it solves is access. On a 60 m alumina calciner stack, a stacker-reclaimer boom, a conveyor gantry running for kilometres, or a tailings storage facility (TSF) embankment, a conventional close visual inspection means scaffold, an elevated work platform, or rope-access technicians — all slow, expensive, and high-risk. A drone reaches the same surfaces in minutes, flies a repeatable path, and brings the inspector a sharper view than the naked eye from a cherry picker.
Technically, the aircraft carries a high-resolution RGB sensor — and often a long-range optical zoom or a thermal payload — and is flown at a controlled stand-off distance from the surface. The pilot or an automated mission maintains overlap and consistent stand-off so that every square metre is captured at a known GSD. The output is reviewed by a competent person, not the drone: the UAV is a remote-sensing tool, and the engineering judgement stays with the inspector.
Key point: A drone inspection survey is not a replacement for a structural engineer's assessment — it is a far better way to feed one. The deliverable is evidence, captured safely and repeatably. The value comes from pairing that evidence with a competent person who can classify defects against the relevant standard.
Why drone inspection matters
The safety case is the strongest one. Falls from height remain one of the leading causes of workplace fatalities in Australian heavy industry, and the WHS Regulations 2011 place a clear duty on operators to eliminate the risk of a fall so far as is reasonably practicable before relying on controls such as harnesses or platforms. A drone inspection removes the person from the hazard entirely for the data-capture phase. On a live processing plant, it also avoids the production interruption and confined-space permits that hands-on access to chutes, bins and ductwork would demand.
The commercial case follows close behind. Unplanned downtime in mineral processing routinely runs to tens of thousands of dollars per hour, and a structural defect found early — a fatigue crack at a conveyor truss node, coating breakdown on a stack liner, settlement on a TSF crest — is a planned repair rather than a forced outage. A drone inspection survey lets you inspect more assets, more often, for less, which shifts maintenance from reactive to condition-based.
There is also a coverage advantage that is easy to underestimate. A two-person rope-access crew might cover one stack in a shift; a single drone sortie can image the same stack, the adjacent transfer tower and the conveyor run back to the next drive in the same window, producing a complete, time-stamped photographic record. That record becomes the baseline for the next inspection, so deterioration is measured rather than guessed.
The drone inspection survey process
ISS follows a structured inspection workflow refined across mining, processing, ports and infrastructure assets. A typical single-asset inspection — a stack, a headframe, a transfer tower — takes half a day on site plus one to three days of review and reporting. The process is non-contact and, for most assets, can be done while the plant is running.
Step 1: Scoping and risk assessment
Before mobilisation, ISS reviews the asset, the airspace and the site hazards. We confirm the defects of interest (cracking, corrosion, coating, deformation), the required GSD, and whether photogrammetric geometry is needed. A JSA and a CASR Part 101 airspace assessment are completed, including any controlled-airspace or aerodrome proximity issues and the exclusion zone around people and live plant.
Step 2: Ground control and reference (where required)
If defects must be located on a 3D model or compared between inspections, ISS establishes ground control points using a Leica or Trimble GNSS receiver and total station. For pure condition imagery this step can be omitted, but georeferencing is what turns a folder of photos into a measurable, repeatable inspection.
Step 3: Flight planning
The inspection is planned as a series of controlled passes at a fixed stand-off — typically 3-10 m from the surface — to hold a consistent GSD. For complex geometry, ISS uses automated terrain- and structure-following missions so coverage and overlap are guaranteed rather than left to the pilot's eye.
Step 4: Data capture
The aircraft flies the planned mission while the payload captures high-resolution stills and, where required, zoom detail and thermal imagery. The pilot maintains visual line of sight and the exclusion zone throughout. On a 50-60 m structure, full close-range capture is usually complete within one to two hours.
Step 5: Image quality assurance on site
Before demobilising, the crew reviews imagery on site for focus, exposure, coverage and overlap. Re-flying a missed face costs minutes on site and avoids a return mobilisation — so a coverage check against the asset map is done before the aircraft is packed.
Step 6: Processing and defect review
Imagery is processed into the agreed deliverable — a tagged image library, an orthomosaic of each face, or a textured 3D model. A competent inspector then reviews the imagery, marks defects, and classifies them by type and severity against the relevant standard (for example AS 4100 for steel, AS 3788 for pressure equipment external condition, or asset-specific criteria).
Step 7: Reporting and handover
ISS delivers a defect register with location, photographs, severity rating and recommended action, alongside the raw geotagged imagery and any 3D model. Where the inspection is a repeat, defects are compared to the previous baseline so change is reported, not just current state. Reports are typically delivered within three to five business days.
Equipment and technology
A drone inspection survey is only as good as its optics, its stability in wind, and the discipline of the flight. ISS operates survey-grade and inspection-grade aircraft and calibrates measurement equipment to traceable standards.
Inspection aircraft and RGB payload
ISS flies high-stability multirotor platforms carrying mechanical-shutter RGB sensors in the 20-45 MP class. At a 5 m stand-off these resolve a GSD of roughly 1-1.5 mm/pixel — fine enough to identify hairline cracking, weld defects and early coating breakdown. Obstacle sensing and precise position hold allow safe close-range work near steelwork and live conductors.
Optical zoom and thermal payloads
For assets where stand-off cannot be reduced — energised switchyards, hot stacks, restricted exclusion zones — a long-range optical zoom payload captures detail from a safe distance. A radiometric thermal sensor adds anomaly detection: overheating bearings and motors, blocked or wet refractory, lagging defects, and electrical hot spots on transmission and switchgear.
Survey control: Leica and Trimble
Where geometry is required, ISS uses Leica and Trimble GNSS and total station equipment to place and observe ground control, the same instrumentation behind our photogrammetric and engineering survey work. This is what allows defect positions to be tied to real coordinates for monitoring over time.
Processing and modelling software
Imagery is processed in industry-standard photogrammetry software to produce orthomosaics and 3D models, with point clouds exported to common formats (LAS, LAZ, E57) when the inspection is paired with as-built or terrestrial laser scanning data.
Key point: Stand-off distance, not just sensor megapixels, sets the achievable detail. A 45 MP sensor flown at 15 m resolves less than a 24 MP sensor flown at 4 m. The skill in a drone inspection survey is flying close and steady enough, safely, to capture the GSD the defect actually requires.
Accuracy and standards
Two kinds of accuracy matter in a drone inspection survey: how small a defect the imagery can resolve, and — where geometry is captured — how precisely a defect can be located in space. The table below summarises what ISS achieves and the benchmarks for comparison.
| Parameter | ISS specification | Typical benchmark | Notes |
|---|---|---|---|
| Image GSD (close range) | 1-3 mm/pixel | 5-10 mm/pixel | At 3-10 m stand-off |
| Smallest resolvable defect | ~0.5 mm crack width | ~2 mm | Subject to lighting and surface |
| Defect location (georeferenced) | 20-50 mm | 100 mm+ | With ground control |
| Thermal sensitivity | <0.05 °C NETD | 0.1 °C | Radiometric payload |
| Coverage completeness | 100% of nominated faces | Spot checks | Verified against asset map |
The inspection itself is conducted against the standard relevant to the asset — AS 4100 for structural steel, AS 3788 for in-service pressure equipment external inspection, AS 1418 and AS 2550 for cranes and runways, and dam-safety guidelines such as ANCOLD for TSF embankments. CASA airspace and operational compliance is governed by CASR Part 101 and the associated Manual of Standards. ISS records the standard applied, the inspector's competency, and a measurement-confidence statement with every report.
When you need a drone inspection survey
A drone inspection survey earns its place wherever access is the bottleneck or the hazard.
Mining and mineral processing
Conveyor gantries and transfer towers, crusher and mill structures, stacks and ducting on calciners and smelters, TSF embankments and spillways, and headframes. Across the Pilbara, Bowen Basin, Kalgoorlie Goldfields and Mount Isa, ISS uses drone inspection to cover remote, high and live assets without standing down production.
Ports and bulk handling
Ship loaders and unloaders, stacker-reclaimers, conveyor runs and wharf superstructure. Marine and bulk-handling structures combine height, corrosion and constant operation — exactly where a drone inspection survey removes risk while keeping the berth working. See our ports and maritime industry page for related services.
Power, energy and infrastructure
Transmission towers and lines, switchyards, boiler houses and stacks at power stations, solar farms, and bridges. Thermal payloads add electrical and mechanical anomaly detection to the visual record.
Shutdowns and turnarounds
In a planned outage, a drone inspection survey captures asset condition faster than scaffold can be built, feeding the scope before the shutdown and verifying work after it. This pairs directly with shutdown and turnaround surveying.
⚠️ Watch out: A drone inspection does not by itself satisfy every mandated inspection regime. Some pressure-equipment and crane standards still require hands-on or NDT inspection at defined intervals. Used well, a drone survey extends the interval between intrusive inspections and targets them — it does not blindly replace them. Confirm the regime that applies to your asset.
Deliverables
What ISS hands over is scaled to the decision you need to make.
| Deliverable | Description | Typical format |
|---|---|---|
| Geotagged image library | Every captured image, organised by asset face | JPG/TIFF + position data |
| Defect register | Located, photographed, severity-rated defects with recommended action | PDF + spreadsheet |
| Orthomosaic of each face | Flattened, scaled image of each elevation | GeoTIFF |
| 3D inspection model | Textured model with defects pinned in 3D | OBJ/FBX + web viewer |
| Thermal report | Anomalies with radiometric temperatures | PDF + radiometric imagery |
| Comparison report | Change against the previous baseline inspection |
For most clients the core deliverable is the defect register plus the raw imagery; the 3D model and comparison report add the most value where the asset is inspected repeatedly and deterioration needs to be tracked.
Cost factors
Pricing is project-specific; ISS provides a fixed-price quote after a short scoping call. The main drivers are below.
| Factor | Impact on cost | Typical range |
|---|---|---|
| Asset height and complexity | More faces and tighter geometry mean more capture and review | $2,000-$6,000 per asset |
| Airspace and exclusion zones | Controlled airspace or live-plant approvals add coordination | +$500-$2,000 |
| Required GSD | Finer detail means closer, slower flying and more images | Baseline to +30% |
| Deliverable depth | Raw imagery vs defect register vs georeferenced 3D model | +20-60% |
| Thermal payload | Adds capture and a second analysis pass | +$800-$1,500 |
| Travel and remote sites | FIFO and mobilisation outside major centres | At cost |
ROI context: A single rope-access campaign on a major stack can run well past $30,000 once access, standby and downtime are counted, and it puts people at height. A drone inspection survey covering the same asset typically costs a fraction of that, captures more, and removes the fall risk — so the payback is usually realised on the first inspection, before any defect is even found.
How ISS delivers it
ISS is an independent industrial surveying firm: we are not tied to any aircraft brand or maintenance contractor, so the inspection serves your asset, not an upstream agenda. We operate under a current CASA Remote Operator Certificate with licensed RePL pilots, registered aircraft and aviation-endorsed public liability insurance, and we manage all CASR Part 101 airspace compliance on your behalf.
Crucially, the same team that flies the UAV and aerial surveys also runs our engineering and mechanical surveying work — so when a drone inspection survey finds something that needs measuring, we can bring a total station, laser scanner or photogrammetric capability to bear without re-engaging a new contractor. The drone inspection becomes the front end of a complete condition and dimensional picture, with a competent person classifying defects against the right standard at the end of it.
Frequently asked questions
How accurate is a drone inspection survey?
For condition assessment, ISS captures imagery at 1-3 mm/pixel GSD on close-range work, which resolves hairline cracking, weld defects and early coating breakdown — comparable to a hands-on close visual inspection. Where geometry is required, ground control lets us locate defects to within 20-50 mm on a 3D model for repeat monitoring.
Can the inspection be done while the plant is running?
Usually, yes. The capture is non-contact and most live assets can be inspected without standing down production, provided an exclusion zone can be maintained around people and operating plant. Energised switchyards and very hot surfaces are flown from a safe stand-off using an optical zoom or thermal payload.
Does a drone inspection satisfy mandatory inspection requirements?
It satisfies many condition-monitoring and visual-inspection needs, but some pressure-equipment, crane and dam regimes still require hands-on or NDT inspection at defined intervals. A drone inspection survey is best used to extend those intervals and target intrusive inspections where they are needed. ISS will confirm the regime that applies to your asset during scoping.
How long does it take and what do we receive?
A single asset is typically half a day on site plus one to three days of review. You receive geotagged imagery, a defect register with severity ratings and recommended actions, and — where required — an orthomosaic, 3D model or thermal report. Reports are usually delivered within three to five business days.
Do we need our own CASA approval?
No. As the operator, ISS holds the Remote Operator Certificate and manages all CASR Part 101 compliance, airspace approvals and insurance. You simply need to provide site access and the relevant site inductions.
Request a quote
If access, height or downtime is making your structural and asset inspections slow, expensive or hazardous, a drone inspection survey is very likely the safer and cheaper path — and the payback usually lands on the first inspection. Tell us the asset, the location and the defects you care about, and ISS will scope a fixed-price drone inspection survey, recommend the right payload and deliverables, and manage every part of the CASA compliance. Call 0407 057 015 or visit industrialspatial.com to discuss your requirements. We are CASA-certified and operate across Australia.