Air Safety

The fact is that powerlines proliferate throughout rural Australia and if you fly low without knowing what you’re about, you’ll sooner or later hit one. You might be lucky and get away with it with no more than the fright of your life. But statistically the chances are that you won’t have to worry any more – about wires, flying, or anything else. The rest will be up to your executor.

The problem is not so much those strings of mighty steel pylons that march over hill and dale carrying hundreds of thousands of volts between major centres of population. Nor even the familiar three-wire high tension lines that parallel major roads throughout much of our settled areas.

No, the great snare for unwary aviators is the humble singlewire powerline used almost universally in rural areas to bring the benefits of civilisation to farm houses, shearing sheds and other isolated country buildings. Not only do such lines have extremely long single-wire spans between poles, being “earth return” systems that create an electrostatic field in their vicinity they are deliberately routed across country and away from roads to minimise electrical interference.

These two characteristic make them extremely hard to detect from the air. The distance between the poles precludes any impression of “a line of poles” – the best visual cue to the presence of a powerline, and as often as not the poles themselves may be hidden by stands of trees. The nett result is that for a lowflying aircraft there may be an invisible wire where it is least expected.

Let’s look at some actual examples:

• A young farmer was harrowing a paddock on his father’s property. Suddenly the how: of an aero engine drowned out the noise

of his tractor and an Airtourer flashed across his path a low level.

The unexpected beat-up came as no great surprise; it had happened several times before – its pilot was engaged to the young farmer’s sister. But as he watched the Airtourer zoom up and bank away this time, he was horrified to see its port wing slice into the nearby single wire powerline that ran towards the homestead.

The wire snapped, the port wing dropped and hit the ground, and the aircraft cartwheeled: as it did so, the starboard wing crumbled and the nose slammed into the paddock. In moments the wreckage was engulfed in flames . .

• The owner of a Tiger Moth took off from a country aerodrome to fly to a friend’s farm.

Once clear of the circuit area he descended and flew cross country to the property at low level. The pilot knew the layout of powerlines on the farm, and sighting his friend driving a tractor, he dived the Tiger at it, waving vigorously as he flew past.

Zooming up over two sets of powerlines, he dived again, this time towards an adjoining paddock where a second tractor was being driven by his friend’s brother.

Again he climbed, circled back towards the first paddock and dived a third time, passing very low in front of his friend’s tractor. In his exhuberence, he had completely forgotten the single wire powerline that now lay directly across his path.

Suddenly sighting the wire, he gave the engine full throttle to try and lift the aircraft over it, but the undercarriage caught on the line. The Tiger continued ahead for about 50metres, decelerating rapidly as the wire stretched. Then the wire recoiled, flicking the aircraft around in the opposite direction, and it fell heavily to the ground with almost no forward speed.

Miraculously, though the port wings were crumpled, the fuselage buckled, the engine dislodged and the propeller splintered, the pilot clambered out of the wreckage with only scratches. • Making a local flight in a hired Cessna 172, an earth moving contractor who held a private licence flew his three passengers low over a property to point out the dam that he had just built. Climbing to clear a powerline, he then closed the throttle and descended again to a height of about 30feet. As he did so, the undercarriage struck another powerline which ran along the paddock boundary, pulling the aircraft into a steep dive. Hitting into the ground nose-first, it somersaulted, breaking off the engine and tail structure.

All four occupants suffered serious injuries and the pilot died several days later.

• Towards the end of a training flight, a young “C” rated instructor’s Piper Cherokee was seen returning from the training area at low level. Flying at an average height of around 15feet which varied only enough to clear occasional trees, the aircraft flew into an unseen single wire powerline.

Taking the wire with it, the Cherokee nosed up steeply into a vertical attitude, stalled, fell over on to its back, and crashed to the ground upside down. The aircraft burst into flames and both the instructor and his pupil were killed.

• The owner-pilot of a Cessna 150was taking a passenger for a flight. Sighting a farmhouse where a friend of the passenger lived, the pilot descended, as he put it later, “to allow him to have a good look at the property. ”

Approaching the house at low level, the Cessna was converging at an acute angle with the unseen single wire powerline that supplied the building. The undercarriage caught on it and the aircraft skidded along the wire, lifting it off its closer poles.

The pilot attempted to put the aircraft down straight ahead in a paddock beyond the house, but the Cessna, still restrained by the wire, fell heavily to the ground and cartwheeled.

Although the wreckage did not burn, the aircraft was damaged beyond repair and both occupants received·severe-injuries.

The forgoing accidents all happened because the pilots involved made hasty, ill-considered decisions to descend to extremely low levels without heeding the possible dangers of doing so. But sometimes even “safe” low flying is not immune from the danger of unseen wires. Nor are those “easy to see” major powerlines totally exempt in particular circumstances. Consider these two instances: soon after taking off from a private airstrip in hilly country on a day of rain and low cloud, two private pilots in an Auster Aiglet decided that as the cloud lay close to the hilltops on their proposed track, it would we safer to divert via lower country in a nearby river valley. Turning to fly through a saddle in the hills to reach the valley, the Auster flew directly into a powerline which spanned the saddle 150feet above its lowest point.

The impact shattered the wooden propeller and snapped the power cable in two places some 30metres on of the impact point. With the long section of wire tra1hng from the engine cowling, the pilot in command had only limited control, but he managed to forced-land in a ploughed paddock that lay directly ahead.

On touch-down the undercarriage dug into the furrows and the Auster somersaulted on to its back. Fortunately, neither pilot was injured.

• Making a local flight from a training aerodrome near the coast, the restricted private pilot of a Cessna 152 flew for a time in the designated training area. Throwing caution to the winds, he then decided to follow the coast where timbered ranges rose steeply from the water’s edge. Flying at about 500feet just to seaward of the beach, he continued until he reached a river valley almost a kilometre wide which joined the coast at right angles. On either side of the valley the terrain rose above the height at which the aircraft was flying, and the pilot decided it would be interesting to return some of the way to the aerodrome up the river valley.

Turning into the valley, he noticed that its floor rose as it continued inland and he applied power to climb. No sooner had he done so than there was a frightening metallic bang on the starboard wing. Even so, the aircraft continued to handle normally and the pilot was able to reach the aerodrome and land safely.

Have you an air safety story to tell? Particular: one a lesson that might save other pilots from making a similar error of judgement? If you have, write to Macarthur Job, cl- Australian Aviation, PO Box 3105, Weston Creek, ACT 2611. Contributors to this series are assured their anonymity will be fully respected!

After he had done so, he found there was a massive gash in the leading edge of the wing where the metal skin had been torn back as far as the main spar.

It was found later that the Cessna had struck one cable of a major powerline spanning the valley from pylons on the hilltops on either side. The pilot said he did not see the powerline at any time. This was hardy surprising -the line spans a distance of 650 metres and the point where the aircraft struck itwas actually 250 feet above the valley floor.

From the air the only cues to the presence of the powerline were the steel pylons on which it was carried. The two that supported it on either side of the valley were surrounded by tall trees and would not be visible from an aircraft flying in the valley below their level.

So what are we to learn from all this?

The instances quoted surely speak for themselves. Would-be low flyers would do well to cash in on other people’s costly experiences while they can -the price of learning the same lessons first hand could be more than any pilot would want to pay!

Spur-of-the-moment impulses to fly low in any circumstances are a proven recipe for disaster. Even taking chances where there is little real possibility of encountering wires is simply not worth the risk.

Powerlines today are literally everywhere there is habitation.

They span rivers, often far above the water, and cross valleys from hilltop to hilltop. In mountainous country wires can be found at heights as much as 300or 400feet above the ground.

You just cannot be too careful!