Electrical wires and other cables are statistically one of the most significant hazards for helicopter especially for Low Altitude Helicopter Operations (LALT) and may result in fatal accidents. This article presents the EASA animation “Helicopter wire strike avoidance – Wires in the helicopter environment” and develops the good practices introduced in this video that can help you avoid striking cables.
Striking wires may have critical consequences: it results in fatalities in approximately 30% of the accidents and up to 60% when operating in Instrument Meteorological Conditions (IMC) or at night. Wire and obstacle strike is one of the top operational causes of fatal Rotorcraft accidents, as rotorcraft fly approximately 90% of their time in LALT operations in the wire environment.
Besides, number of flight hours is not a guarantee for avoiding wires, as most wire strike accidents statistically occur to experienced pilots with more than 2000 flight hours and good knowledge of the area. As reported by numerous accident investigations, even very experienced pilots, to avoid IMC flight conditions and looking for visual contact with the ground, forget to ensure that no wires are in the area.
In the video, a student pilot is on a Visual Flight Rules (VFR) training flight with a flight instructor in a Cabri G2 helicopter. The flight takes place in a mountainous environment in VFR conditions: it is a sunny day with no clouds in sight. The flight instructor advises the trainee to keep flying above 500 ft. in compliance with the Standardised European Rules of the Air (SERA) and to use visual cues and landmarks to help navigating. The trainee asks to have a closer look at a castle over a hill and while ascending to fly over the castle, he becomes blinded by the sunlight.
Inadvertently the helicopter descends below the minimum altitude over the hillside and gets dangerously close to electrical wires ahead. The student pilot is instructed to climb and turn right to avoid striking the wires. Even in Visual Meteorological Conditions (VMC), it might be difficult to see wires in the flight path and collisions with cables are usually critical and lead to fatal accidents. The video mentions two examples of accidents: Airbus AS 350 BA helicopter of 30 July 2015 in Canada and EC 120 of 3 March in Slovakia.
There are a number of things that you can do to help mitigate the risks.
Analysis of helicopter occurrence data has identified a number of accidents and incidents where loose items in the cabin have exited the helicopter and contacted the tail rotor. In some cases this has resulted in a complete loss of control of the helicopter. Pilots and crews must ensure that all items in the cabin are securely stowed before take-off, even if operating with all doors fitted. Passengers must be briefed on the dangers of loose items in and around the vicinity of helicopters.