Beware of cables


  • As the helicopter pilot prepared to climb again after depositing an external load, he noticed some unusual vibrations and thus decided to execute a precautionary landing. Since a flight assistant had noticed a bird in the vicinity of the site, the pilot initially assumed that the rotor blades had been damaged due to bird strike. But since there were no signs of blood or feathers, the pilot and his assistant looked for other possible causes, and after a while they discovered a severed tele-phone line near the site of the incident.
  • The glider had to land off-airfield due to a lack of thermals, and on short final it collided with a power transmission line and severed all three cables. The glider was seriously damaged, but mi-raculously the occupants remained unharmed.
  • While passing through mountainous terrain during a distance flight, the pilot of a hang glider failed to notice the cables of a goods cable car and collided with them. He fell more than 200 metres onto rocky terrain and was killed upon impact.
  • As it was preparing to land on a plateau in the mountains, the hot-air balloon was suddenly struck by a strong gust of wind (Foehn) and became entangled in a transport cable suspended just above the ground. The balloon continued to move towards the steep drop at the edge of the pla-teau. The transport cable severed the load-bearing cables between the balloon and basket, as a result of which the basket plummeted to the ground and all occupants were killed.

FOCA comments

These are just a few examples of incidents and accidents involving collisions with cables. Unfortu-nately, the FOCA has received many more reports of this nature. Such occurrences do not always result merely in material damage, and they are by no means restricted to one form of air transport: helicopters, gliders, balloons, hang gliders and aeroplanes are all equally endangered. Cables that are difficult to recognise or have not been registered, have been erected illegally or have not been re-moved after work has been completed, are among the most frequent causes of collisions in the gen-eral aviation segment. The number of entries in the aviation obstacles database underscores the fact that this hazard should not be underestimated: in the course of 2007, a total of 373 cables were erected and 410 were registered in Switzerland, and 3,221 modifications of aviation obstacles were recorded. It is important to be aware, however, that a registration obligation does not apply for all ca-bles: some cable systems can be erected that do not have to be registered, depending on their di-mensions, height, type and the relevant legal requirements.

Efforts aimed at drawing attention to the dangers posed by cables and ways in which the risks can be reduced have been initiated on a number of occasions in the past:

  • In 1972, the FOCA published a fact sheet warning pilots to beware of cables.
  • By the end of 2007, a total of 300 facilities had been dismantled and removed since the initiation of the "REMOVE" project in 2001, which involved REGA (Swiss rescue and emergency service), the Swiss airforce, Skyguide (Swiss Air Navigation Services), private aviation operators and the FOCA.

While the various measures have succeeded in promoting awareness of the problem, too many inci-dents nonetheless continue to occur. In view of this, the FOCA has decided there is further need for action, and has launched a safety awareness campaign based on a poster intended to draw the atten-tion of the various players in the civil aviation sector to the existing risks. In this way the FOCA wants to make a significant contribution towards the reduction of the potential dangers posed by cables and wires. The message is as follows:

Minimise the risk of a collision with cables by obtaining vital information, making adequate flight preparation, keeping your eyes open and adopting appropriate flight behaviour!


Pre-flight preparation

  • Always use the latest versions of maps. For low-altitude flights, be sure to consult regional avia-tion obstacle maps, ensure that you have any existing updates at your disposal, and pay careful attention to them.
  • Familiarise yourself beforehand with the area concerned, preferably with the aid of flight assis-tants or other specialists on the ground.
  • Consult with local residents or colleagues who are familiar with the area concerned.

Look out - scan the area

  • Not all obstacles are necessarily included in local maps and/or recorded in electronic collision-warning devices.
  • Adapt your flight behaviour to the situation at hand; consider your aircraft's power reserve and the local wind conditions (safety margin in height!), etc.
  • Always stay alert and aware. Situational awareness and perception can be reduced due to ex-ternal or human factors, e.g.:
    • Obstacles to visibility (dazzling sunlight, shadows, mist, fog banks, smoke, lack of contrast, etc.)
    • Physical influences (lack of oxygen, lack of food/liquid intake, extreme temperatures, over tiredness, etc.) or mental (time pressure, pressure to perform, easing of tension after comple- tion of the task, etc.).

Report / inform

  • Report any cables that are obviously no longer in use and/or have not been registered.
  • Report any incorrect or inaccurate markings.
  • Warn others: inform your colleagues, talk to local residents and to the relevant authorities.

Owners/operators of cables:

  • Report the location of the cable(s) in the proper manner and without delay, and maintain and operate them in accordance with the relevant provisions governing marking and visibility.
  • Remove any cables that are no longer required, and report their removal to the relevant authori-ties.