02 Feb Asset condition inspection: Why the grid needs more than one approach

Keeping the electricity network reliable has always depended on a careful balance of experience, planning, and the right tools. For transmission and distribution network operators managing high-voltage overhead line infrastructure, asset condition inspection is not about choosing one ‘best’ method, but about using the right combination of approaches to protect people, maintain performance, and use resources wisely.

Today, three core inspection methods work together across the grid:

• In-person foot patrols and climbing teams
• Helicopter-based aerial surveys
• Drone-based aerial inspections

Each plays a distinct and valuable role.

In-person inspections: essential where action is required

Climbing teams remain critical to grid operations. When physical work must be carried out – repairs, component replacement, fault response or detailed mechanical assessment – there is no substitute for skilled engineers on the structure.

They are essential for:

• Physical intervention, repair and component replacement
• Detailed mechanical inspection that can only be carried out hands-on
• Fault response and safety-critical work on live or high-risk assets

But grid operators are increasingly moving towards a “climb to do, not to view” approach. The principle is simple: limit time spent at height to tasks that genuinely require hands-on intervention. Towers are complex and potentially hazardous environments, so protecting experienced people and using their skills where they add most value is essential.

With an expanding grid, an ageing workforce and fewer engineers entering overhead line roles, making the best use of specialist time has become a growing priority. These specialist teams bring a rare combination of skills: working safely at height, operating in close proximity to live cables, and applying engineering judgement built over years of experience. Their expertise is a constrained and highly valuable resource, and inspection strategies that enable them to focus their time on the work that genuinely requires human intervention play an important role in protecting both people and network reliability.

Helicopter surveys: rapid, wide-area situational awareness at scale

Helicopter surveys remain essential where speed, scale and system-wide situational awareness are required. They are ideally suited to long-range overview inspections, enabling large sections of the network to be assessed quickly and supporting rapid response following major weather events. While they are not suited for close-quarter inspection or detailed underside views, this defines their strength: delivering fast, wide-area intelligence that guides where more targeted inspection methods should be applied.

They are particularly valuable for:

• Rapid corridor-wide assessment of large network sections
• Post-storm and emergency response inspections
• High-level identification of emerging risks and anomalies
• Carrying multiple sensor types for strategic condition monitoring

Drone inspections: bringing close-quarter insight without climbing

Drone technology adds something different: detailed, close-range condition data without placing people at height. While basic drone operations rely on manual piloting and line-of-sight constraints, highly autonomous systems unlock capabilities that change what’s operationally feasible at network scale. They allow inspection teams to:

• Capture high-resolution, close-quarter imagery of individual components and connection points
• Access detailed inspection angles that cannot be achieved from manned aircraft (including underside and oblique views)
• Reduce the need for non-essential climbs by providing visual condition data remotely
• Build consistent, repeatable digital records of asset condition that can be compared over time

What makes highly autonomous inspection different

Highly autonomous drone operations represent a step change from manually piloted systems. Rather than requiring skilled pilots on-site for every flight, advanced autonomy allows inspections to be carried out in a consistent and structured way while responding in real time to the environment and the asset itself. Rather than simply following fixed routes, advanced autonomy can sense and adapt to actual network conditions, including complex scenarios such as inspecting components on moving conductors. It enables repeatable, high-quality data to be captured and compared over time (increasingly by AI and Machine Learning algorithms), supporting trend analysis rather than one-off observations.

BVLOS capability extends this further by removing the constraints of short-range, line-of-sight flying and unlocking far greater operational efficiency. It can allow multiple towers and longer sections of network to be inspected within a single flight, reduce dependency on repeated land access permissions, and enable inspection operations to be coordinated from a central control room.

This means the most valuable resource – the autonomous system supervisor – can remain highly utilised, potentially overseeing multiple missions rather than spending time travelling between sites, helping scale inspection activity without proportionally increasing cost or complexity.

Together, autonomy and BVLOS operations transform drone inspections from isolated tasks into a network-ready inspection method that can be planned, repeated and scaled in line with operational demand. Manual drone operations remain valuable for targeted investigations and specialist surveys – but for routine, large-scale asset inspection programmes, highly autonomous systems enable consistency and efficiency that would be impractical to achieve manually. This is where drone inspection becomes a powerful complement to existing methods. It does not replace helicopters or climbing teams; it strengthens both by improving the quality of information used to decide when and where physical intervention is needed.

A joined-up inspection toolbox and its benefits

The most effective inspection strategies do not treat these methods as competitors. They treat them as a coordinated system:

In-person: Physical intervention, fault repair, specialist engineering tasks.

Helicopter: Rapid network-wide situational awareness and corridor assessment, carrying multiple sensors including thermal (infrared) for hotspots and abnormal heating, LiDAR for vegetation encroachment and clearances, standard visual imagery (RGB) for visible defects, third-party activity and environmental risks, and ultraviolet (UV) for corona discharge and insulation issues.

Drone: Granular, close-quarter condition analysis for targeted asset assessment. Autonomous systems excel at capturing structured, repeatable datasets – ideal for AI/ML analysis, pre-tender contractor briefs, assurance requirements, and maintenance baselines. Drone operations reduce unnecessary climbs, improve precision, and lower environmental impact through minimal noise, emissions, and site access needs.

Together, they allow operators to:

• Improve health and safety by reducing unnecessary exposure to hazardous environments
• Make the best use of highly skilled resources that are in short supply
• Use aviation resources efficiently and safely
• Improve asset condition intelligence
• Plan development and maintenance programmes with greater confidence

In an environment where electricity networks are under increasing pressure to perform, these complementary approaches help ensure inspection remains resilient, scalable and responsible.

Supporting the people who keep the lights on

Grid operators face mounting pressure to deliver reliability with constrained resources and an ageing workforce. Autonomous inspection systems don’t replace expertise – they amplify it. By providing detailed, structured asset intelligence, these systems enable skilled teams to focus where human judgment and intervention matter most: complex diagnostics, repair planning, and physical remediation.

The goal isn’t to do less with less. It’s to do more with what we have – improving safety, precision, and network resilience while respecting the environment and communities we serve.