"Cable clutter" as an underestimated risk

Flying in cable-rich regions such as the Swiss Alps is one of the most challenging tasks for helicopter pilots. Especially for pilots who mostly fly in the less cable-infested lowlands, train mainly in the simulator or have only a few hours of flight time.
If you make external landings, specific preparation is important.   

Authors: Claudia Zürcher, Samir Ulrich, SHeV

The danger posed by obstacles such as power lines, cable cars or hay ropes is omnipresent. Often overlooked or misjudged, cables can have fatal consequences for helicopters and their crews. There are many reasons for this:

• Inadequate flight preparation
• Incomplete maps or missing updates
• Poor visibility and optical contrasts
• Excessive demands or negligence
• Lack of assessment of the cable hazard

Particularly for pilots who complete their training on the Central Plateau, in simulators, abroad or around airfields, specific additional training on cable hazards is an important part of further training. A mandatory training module on cable risks when obtaining a private pilot's license (PPL H) or specific training units, such as those offered for Alpine flights, could make a decisive contribution here.

Tactics for safe flying

Successful management of flights in cable-rich areas requires adapted flight tactics. The key points are

• Approach and departure: The approach angle should always be adapted to the cable situation. The take-off should always follow the same route as the approach - regardless of the wind conditions.
• Visibility of cables: Power lines should preferably be crossed directly above the pylons, as visibility of wires between the pylons is often poorer.
• Landing sites behind huts: There is an increased risk here, as wires are often stretched from these.
• Valley flights: It is safer to approach a site from the center of the valley rather than from the side of the valley, as this provides a better view of taut cables.
• Navigation technology: Modern apps such as AirNavPro, ForeFlight or Swisstopo can be a valuable aid. SplitView views on the EFB make it possible to detect cables close to the ground at an early stage and still navigate cleanly.
• Adjust flight speed: In cable-rich areas, the speed should be reduced in order to be able to react to suddenly visible obstacles.

The limits of cable cards

Cable maps are important tools, but they are not without their pitfalls. Incorrect entries, unreported or newly installed cables and incorrectly marked or long-removed cables are common problems. Cables below a height of 25 meters above ground do not have to be reported and are therefore not marked on the official FOCA obstacle map. New obstacles are announced by NOTAM, but even these are not always complete. A personal reconnaissance of the area with today's standard aids, especially shortly before the flight, is crucial.

Prevention through technology and collaboration

Auxiliary devices: GPS systems with obstacle maps or FLARM/FLOICE  can detect cables and help to avoid collisions. However, even these systems are not always up-to-date or comprehensive.

Markings: Ball markings or cones can provide clues to cables, but few cables are marked.

Maintenance and reporting: Faulty signal balls or unused cables should be reported by owners or pilots to obstacles@bazl.admin.ch.

Cooperation with regional pilots can be helpful. They are often familiar with temporary obstacles such as roadworks or cable cars and can provide crucial information. Pilots should never rely blindly on maps and should always use several sources of information. Regularly updating databases and reports from the aviation community can also contribute to improvements.

During transport flights, experienced flight assistants who scan the approach and departure axis for possible cables on site are an enormous safety benefit. In many cases, farmers or employees of electricity companies and railroad systems also know the cable situation and can provide information about it.

If, despite the available aids, the risk of landing is still too high for the pilot, a reconnaissance on foot or by car shortly before the flight is still one of the safest methods of gaining a personal impression of the situation.

Education and cooperation are key

The dangers posed by aviation obstacles are too great to be neglected. More intensive training, the use of modern technologies and increased cooperation between aviation stakeholders, map manufacturers, aviation obstacle owners and the aviation authority can help to significantly increase safety in cable-rich areas.

Ultimately, only those who rely on experience, knowledge and technology in equal measure can minimize the risk of cable accidents in the long term.