The UK's National Grid has a fleet of helicopters to monitor the transmission network. These helicopter teams are part of a 4,000-strong field workforce keeping the grid wires in prime condition.
The helicopters patrol pylons and power lines across the country – a high wire act they have been performing for over six decades to keep the electricity network in functioning all year round. These aircraft have special permission to fly nearer high voltage cables than is normally allowed.
With so much important infrastructure being monitored each year, the aircraft collectively cover around 32,000 miles of network annually on their patrols. The company operates eight helicopters across its networks – three to monitor the 22,000 pylons, 300 substations and 4,500 miles of high voltage overhead line that make up the transmission network in England and Wales; and five to cover the 60,000 miles of lower voltage overhead line on its distribution network that connects to homes and businesses.
The distribution network helicopters operating in the Midlands, South West and South Wales are bright yellow, and the transmission network helicopters covering all of England and Wales are in National Grid’s white and blue livery.
A skilled team in each helicopter is looking for damaged parts, wear and corrosion on the pylons and cables – but they’re also looking for other potential issues in the area like vegetation growing too close to a line. They have even helped rescue livestock they have spotted stuck in bogs and ditches, by calling it in to local landowners.
An experienced pilot keeps the helicopter’s movements steady while specialist observers gather the imagery needed by network engineers by flying close to overhead cables and pylons.
John Rigby is chief pilot at National Grid covering the transmission network, bringing to the role 32 years’ flight experience with the Royal Air Force, Air Ambulance and National Grid. He said: “Our priority is to check the condition of the network’s overhead lines and substations to confirm they are shipshape all year round.
“That means flying closer to the electricity infrastructure than general aviation are allowed, which concentrates the mind – but it’s a very safe and controlled operation, one that our experienced teams have been carrying out for decades.”
The teams also have advanced electro-optics such as thermal imaging cameras and LiDar systems at their fingertips to help identify issues like ‘hot spots’ on overhead lines – a rare occurrence but an indication of an overheating joint that will need fixing to avoid future faults.
National Grid finds that aerial surveys are safer, more cost-effective and less resource-intensive than climbing the entire network of pylons or inspecting the wood poles by foot. It might take three lineworkers on the ground several days to carry out inspections on a handful of towers that would take an airborne observer just hours to inspect.
Crucially the helicopter teams’ work can spot potential issues before they go wrong, feeding back information for National Grid’s overhead line maintenance teams to take action on if needed.
It is estimated that for the cost of running the transmission network’s helicopters, there’s a tenfold cost saving in refurbishment and fault prevention on the high voltage grid.
In some cases pylons and lines can’t be inspected closely by helicopter, for example those in heavily built up areas or where there are significant numbers of people or livestock around. In that case National Grid will use its fleet of drones – and a team of skilled operators – for use in these situations. The drones are equipped with similar technologies to the helicopters to help identify issues on the network. Now the company is even trialing autonomous drones. While drones have benefits in terms of cost and efficiency, helicopters have their own advantages – they can cover longer distances, and they don’t require access to the land close to powerlines. Overall this fleet of helicopters and drones is essential to the maintenance of the UK National Grid.