The runway is 3,543 feet of asphalt on the Welsh coast, straight and flat, open to the Irish Sea wind.
Halfway down it, two white turbines spin in that same wind, about 98 feet from the runway edge.
Each blade tip reaches 152 feet above sea level.
An incoming pilot lines up, descends, and passes a turning rotor off the wingtip.
What that placement did to the runway’s paperwork is the part every visiting pilot now has to plan around.
What a turbine inside the runway strip does to a licence
A licensed runway in the United Kingdom sits at the center of a set of protected invisible surfaces: a cleared strip of ground flanking the pavement, and sloping planes that rise from the edges of that strip and from each threshold. Nothing solid is meant to break through them. The regulator’s job is to be satisfied that a licensed aerodrome is safe for civil aircraft given the physical characteristics of the field and its surroundings.
So an obstacle standing inside that geometry cannot simply be noted and left. That is precisely the situation at Caernarfon Airport in Gwynedd, on the northwest coast of Wales.
The main runway, 02/20, lost its licence because of two wind turbines reaching 152 feet above sea level, installed roughly halfway along its length and about 98 feet from the runway edge. Airfield data puts the towers around 130 feet east of the centerline. The consequence was not closure. The strip became something rarer: a runway you may still use, but only by invitation.
What the airport put beside the runway, and why
Caernarfon Airport lies four nautical miles southwest of the walled town of Caernarfon, on flat coastal land at Dinas Dinlle that was once a wartime Royal Air Force station. Runway 02/20 runs roughly north to south into the prevailing sea breeze, making it the longer of the airfield’s two paved strips.
The crossing runway, 07/25, is 3,058 feet long and remains the field’s single licensed runway, which is why the airfield did not shut. The machines the airport’s directors applied to build were rated at 250 kW each, sited east of 02/20.
Regional coverage of the application reported that an earlier scoping exercise had considered 14 turbines before the scheme was cut to two placed east of the strip to reduce bird collision risk. The stated aim was to safeguard the airport’s future, protect jobs and cut the site’s carbon footprint. Objectors noted before construction that towers inside the runway strip would leave 02/20 unlicensed. That is exactly what the published information now records.
The information pack every pilot now carries
Civil light aircraft began using the old wartime runways in growing numbers from the end of the sixties, and the aerodrome gained a full operating licence in 1976. That is the standing the main runway no longer has.
The airport publishes an information pack for visiting pilots. Runway 02/20 may be used only on the understanding of the stated conditions and with advance permission from the airport manager. The official aeronautical data carries the same point plainly: the strip is unlicensed and unavailable for any aircraft requiring a licensed runway.
The data also carries a restriction written around the towers themselves: no helicopter movements within roughly 1,000 feet downwind of the wind turbines. Helicopters are not incidental traffic here. Air ambulance and coastguard operations work from Caernarfon, large S92 search and rescue helicopters are based at the field, and light aircraft must keep at least four miles of separation behind an S92 in the air and three minutes on the ground.
Why runway wind turbines keep appearing beside active strips
Caernarfon is not alone in mixing runway wind turbines with active flying. The airport on Baltra in the Galápagos runs on solar panels and three large wind turbines and has been described as the only airport working exclusively on renewable energy. Two 148 foot turbines went up at East Midlands Airport, considered a first for a UK airport, and a fleet of small wall mounted turbines was installed at Boston Logan.
The pattern holds because airport land is flat, windy and already owned by an operator looking for revenue that needs no extra ground. What separates Caernarfon is location: the towers sit inside the runway strip itself, the protected band that must stay clear for an aircraft drifting sideways in a crosswind. By contrast, a turbine in extreme terrain contends with permafrost and access roads, not landing clearances at a working general aviation field.
At 250 kW apiece, these are modest machines, a small fraction of the output of a modern onshore turbine rated in megawatts. The revenue case was real. So was the permanent cost to runway availability.
What the numbers mean in the air
Runway 02/20’s 3,543 feet is just over two thirds of a mile, tight but usable for most light piston aircraft at sea level. The turbines stand halfway along it. A pilot landing on 02 sees them early and passes them close on the right; landing on 20, a pilot passes them on the left with the same lateral exposure on approach.
Ninety eight feet of separation from a turning rotor is not a clearance any certificated runway would normally be held to. That is what the permanent unlicensing records: tower placement arithmetic is normally finished before the foundations are poured, and here the runway’s status changed to fit the towers.
The airfield remains open, with an aviation museum and café on site, and a licence that still covers flying instruction on 07/25. The two turbines keep turning in the sea wind off Caernarfon Bay. The runway beneath them carries a condition of use instead of a licence, which means one more call to the airport manager before every approach on 02/20.
