Radio mast inspection

A critical piece of harbour infrastructure

Cork Harbour is one of the busiest commercial ports in Ireland, handling a constant flow of vessel traffic. Every ship entering or leaving the harbour relies on communications routed through the client's radio mast in Cobh. Situated on a remote high point in the town — not at a building or facility, but at an elevated, isolated location — this mast is a lynchpin of maritime safety and port operations.

The mast itself is a relatively small stayed lattice steel structure: three sets of stays, each with a lower and an upper stay, supporting the mast and its antenna array. Despite its modest size, its operational importance meant that any downtime was out of the question. The client needed a full condition assessment of the structure — the lattice, the stays, the anchor points, and the antenna mountings — without interrupting a single transmission.

Inspecting a live radio mast without disruption

An engineering consultancy brought Engineers With Drones in to carry out the inspection. The brief was straightforward but demanding: produce a detailed condition report on every element of the mast while it remained live and transmitting.

Two constraints shaped the entire approach. First, the mast could not be taken offline — it handles all ship-to-shore communications for Cork Harbour, and any interruption would have immediate operational consequences. Second, flying a drone close to an active radio mast introduces a risk of radio frequency interference. The frequencies in use at the site were not in the same band as the drone's control and transmission frequencies, so there was confidence that the drone itself would not be affected. However, getting too close could still interfere with the mast's own transmissions.

The solution was to keep the drone at a safe standoff distance throughout the inspection — and this is where high-optical-zoom lenses made the difference.

Three-angle flight profile with high-optical-zoom photography

Because the mast was a stayed structure with three sets of stays, the flight profile had to be carefully designed to avoid any risk of the drone becoming entangled. The team planned a three-angle approach, with each flight path positioned between the stays and aligned roughly 120° apart around the mast.

On each of the three angles, the drone was flown from the base of the mast to the top, capturing the full height of the lattice steel structure in high-resolution detail. The high-optical-zoom lens allowed the camera to get right into the steelwork — individual lattice members, bolted connections, and surface corrosion — all from a safe distance that posed no risk to the mast's radio operations.

Beyond the lattice itself, the team also captured detailed imagery of every stay and anchor point, both on the mast and at ground level. The antenna array at the top of the mast was inspected in the same way, with particular attention to the securing points and fixtures that hold each antenna in place.

Heavy corrosion found in the lattice structure

The imagery revealed a number of issues that required attention. Most significantly, there was heavy corrosion in some of the lattice steel members. The lattice structure itself — the redundancy built into its triangulated design — was the only thing keeping the mast standing in those areas. Had the structure relied on individual members rather than a lattice, the corrosion would have posed an immediate structural risk.

The stays and anchor points were also documented in full, ensuring that the condition report reflected the entire mast assembly and not just the steel lattice. On the antenna array, one or two issues were identified with securing points and fixtures, and these were included in the report alongside the structural findings.

A full condition report with every defect classified

Once the field work was complete, all of the captured imagery was brought back to the office for processing. Each defect was isolated and documented individually: a text description of the issue, a classification level, a severity rating, and a unique reference ID. This meant that every finding could be referenced and tracked through to remediation by the client's engineering team.

The report gave the client a complete, prioritised picture of the mast's condition — which defects needed immediate attention, which could be monitored, and where the structure was in good health. Most critically, it identified the areas of heavy corrosion in the lattice before they could develop into a more serious structural failure.

What the client received