When the ground gets closer

Extra-high-voltage lines as a danger to aviation

Author: Joshu Jullier


It’s a sunny spring day. The sky is full of round, fluffy cumulus clouds; each one looks a bit like an animal or a person. I board the glider. Once in the air, I hang from cloud to cloud and allow myself to be pulled upwards by their updrafts. I’m surrounded by paragliders and birds of prey circling the air with me. At 4 p.m., I feel the air becoming calmer, so I head towards the airfield. Suddenly I can’t find any more upwind. Quite the opposite, the plane just keeps on sinking. The large pointer on the altimeter falls below the 800-metre altitude mark. There are only 400 metres left between me and the ground below. My descent rate is two metres per second, so mathematically I have a flight time of just over three minutes. I urgently need to locate a landing field, a meadow with a length of at least 100 metres where I can land safely. I spot a suitable field within my range. During the final landing stage, I notice something I hadn’t seen until then, shimmering in the evening light in front of me in the field. There’s an extra-high-voltage line directly ahead of me, with pylons at a height of around 60 m. I’m flying too low to attempt a reverse loop. The procedure states that I should fly under the line, because if I try and fly above it, there’s a risk I won’t make it over the conductors. I push the nose of the plane down, the ground gets closer and my speed increases. I see the conductors hovering above my head through the glass canopy. Then the meadow is right there in front of me. I fully extend the air brakes and touch down gently. The plane comes to a halt just before the end of the meadow. I did it!

Gliders are pulled into the sky by a powered aircraft and then soar like birds of prey for hours, held up by nothing but thermals. If the thermals stop unexpectedly, having to make a landing in a field is not unusual. (Photo: areggfoto.ch)
Gliders are pulled into the sky by a powered aircraft and then soar like birds of prey for hours, held up by nothing but thermals. If the thermals stop unexpectedly, having to make a landing in a field is not unusual. (Photo: areggfoto.ch)

Fortunately, this has never happened to me in ten years of gliding. But I’m prepared for it. If something goes wrong, there’s no time to think. So as a pilot, you always have to have a plan B ready in advance, in case something unexpected happens. That’s the only way to be sure that you will react appropriately and quickly enough.

Extra-high-voltage lines: a barely visible obstacle

Unfortunately, time and again, pilots of paragliders, helicopters or aeroplanes don’t see extra-high-voltage lines or underestimate the danger they represent. After all, the pylons are green and well camouflaged, especially in forest areas. The conductors are only clearly visible when they reflect the sunlight in the precise direction of the observer, which only happens for a very short time on any given day. In addition, the chosen line route is adapted as closely to the landscape as possible to avoid any negative visual impact on the scenery. Extra-high-voltage lines near airfields and on flight paths have orange flight warning spheres on the earth cable, which is the uppermost cable. This makes the lines more visible to pilots. But even with this measure, it’s important for pilots to keep a special lookout for extra-high-voltage lines and overhead distribution lines when flying close to the ground.

«If something goes wrong, there’s no time to think. So as a pilot, you always have to have a plan B ready in advance.»

Joshu Jullier

Danger lurks near the ground and on slopes

Paraglider pilots should avoid flying over extra-high-voltage lines at low altitudes because valley winds or flying problems such as collapses can lead to rapid loss of altitude. Ejecting the rescue parachute can also result in an inability to steer the paraglider. A sufficient vertical safety distance must therefore be maintained from the line.

Extra-high-voltage lines should not be flown over at low altitudes.
Extra-high-voltage lines should not be flown over at low altitudes.

Extra-high-voltage lines also represent a danger for helicopters. Since helicopters can land wherever they like, they may come very close to an extra-high-voltage line when landing or taking off. In addition, helicopters often fly at very low altitude. This makes lines crossing a valley particularly dangerous.

What can I do as a pilot?

Before flying, especially in unknown territory, you should carefully study a map of your potential flight routes. Extra-high-voltage lines are marked in red on the glider map. These lines can sometimes help pilots to find their way. Overhead lines are also indicated on the aviation obstacle map provided by swisstopo and on OpenStreetMap maps. The planned route should stay as far away as possible from extra-high-voltage lines, especially when flying in mountainous areas or close to sloping terrain. It’s important to remember that in addition to the large high-voltage masts , there are also smaller distribution system pylons. Cable cars and transport ropes are in fact often more dangerous, because they are very hard to spot. It’s important to obtain detailed information about all these obstacles before flying, and to always fly at a safe distance from them.

Good flight preparation is the be-all and end-all. Extra-high-voltage lines are marked in red on the glider map. (Map: skyguide, swisstopo)
Good flight preparation is the be-all and end-all. Extra-high-voltage lines are marked in red on the glider map. (Map: skyguide, swisstopo)

The pilot can keep a careful lookout for pylons when flying. Pylons are much more visible than conductors. The airspace in the vicinity of extra-high-voltage lines must be kept under close observation. Flying at a sufficient distance from extra-high-voltage lines and other obstacles can help prevent critical situations. Tricks or manoeuvres should be avoided above extra-high-voltage lines. Paraglider pilots shouldn’t thermal or descend over extra-high-voltage lines at low altitude, as this greatly limits the possibilities for changing course at the last minute. The pilot should look for landing possibilities at an early stage so that they can take evasive action if necessary, for instance if an obstacle suddenly blocks their flight path or the altitude is no longer sufficient to return to the intended landing site.

But what if you need to land in a meadow?

Whether it’s a helicopter, glider, paraglider, delta glider or hot air balloon, the choice of landing field is crucial. The following points must be taken into account:

  • Is the landing field large enough?
  • Will the vegetation permit a safe landing?
  • Will the slope of the terrain allow a safe landing?
  • Are there definitely no obstacles to the approach, such as extra-high-voltage lines, distribution system lines, cable cars or animals?

The field is only suitable for a safe landing if the pilot can answer «Yes» to all the above questions.

When landing outside an airfield, the choice of landing field is crucial. There must be no obstacles to the approach, such as extra-high-voltage lines.
When landing outside an airfield, the choice of landing field is crucial. There must be no obstacles to the approach, such as extra-high-voltage lines.

Protection from danger of death has top priority

For Swissgrid, the safety of people and nature is paramount. Consequently, raising pilots’ awareness of the issue of extra-high-voltage lines is the best preventive measure to avoid accidents. It’s important for pilots to be aware of the dangers of extra-high-voltage lines, because electricity flows through them at 1,000 times the voltage of the electricity that comes out of the power outlets in our homes. In the event of a collision, there is a risk of suffering a life-threatening electric shock. An electric shock can occur even without touching the conductor. The extra-high-voltage line must therefore be switched off immediately if an incident occurs. Please alert us via our emergency number 0800 00 45 45.

On each Swissgrid pylon, just below the danger signal there is a plate indicating the emergency number, the pylon number and a QR code. If you need to call the emergency number in connection with an incident, please be sure to quote the pylon number printed on the plate. This will enable us to immediately switch off the affected line. The QR code takes you to information about the pylon and to important rules of conduct that should be observed in the vicinity of an extra-high-voltage line.



Author

Joshu Jullier
Joshu Jullier

Phone +41 58 580 21 11
info@swissgrid.ch


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