The competent authority in Switzerland is the Federal Office of Civil Aviation (BAZL). Objects are considered obstacles to aviation if they reach a height of 25 metres in undeveloped areas and a ground height of 60 metres or more in developed areas. The overview of undeveloped and developed areas in Switzerland can be viewed here.
For highlines under 25 metres off the ground, we recommend that you register the highline with Rega. Voluntarily and free of charge. This is particularly important if the highlines are set up for longer periods.
Specific regulations also apply in areas around aerodromes..
More info: BAZL Aviation obstacles
