Hi there,
That depends on whether you need to be rescued or transported within Switzerland or outside of the country.
Emergency transportation within Switzerland: Compulsory health insurance covers half of the cost of transportation to a doctor or hospital - up to a limit of 500 francs per year. In the worst case, you may have to pay thousands of francs on top of what is covered.
Rescues within Switzerland: If you need to be rescued from a life-threatening situation, compulsory health insurance covers half of the costs - up to a limit of 5000 francs per year.
Emergency transportation and rescue outside of Switzerland: Comulsory Swiss health insurance does not cover the cost of ambulance transportation or rescues outside of Switzerland. However, it does cover (a low) 500 francs of the cost of repatriation to Switzerland for medical care.
Getting a Rega membership can be worth it for some people (climbing enthusiasts, for example). Just note that Rega only covers the costs of transportation in its own emergency vehicles.
A number of supplementary insurance policies provide coverage for rescue operations and emergency medical transportation outside of Switzerland. Some also extend the coverage you get for emergency transporation within Switzerland.
You can find out which benefits each supplemental policy offers and compare costs using the moneyland.ch supplemental health insurance comparison. Just select the "Search & rescue in Switzerland" or "Search and rescue abroad" filters to limit results to policies which include these benefits. You can find exact details about coverage on the information pages of each individual policy.
Best regards from Moneyguru
More on this topic:
Emergency Transportation & Search And Rescue: How To Insure the Cost