Diplomatic Clearances

Foreign state flights over or into Switzerland require special permission, known as diplomatic clearance. This permission is granted by FOCA in consultation with other federal offices.

State flights include flights engaged in missions undertaken by government, military, customs and police authorities. They particularly include flights by order of the state, flights used for transporting heads of state and high-ranking government officials on official duties, flights used in police and customs operations, and all military flights.
Applications for diplomatic clearance must be submitted by the respective state's diplomatic representative in Switzerland. To enable FOCA to grant clearance in sufficient time, applications must be received no later than five working days before the intended flight date. For state flights engaged in transporting dangerous goods (e.g. highly flammable substances), applications must be received at least eight working days in advance.
FOCA will review the application together with the Federal Department for Foreign Affairs (FDFA) and the Federal Department of Defence, Civil Protection and Sport (DDPS). Clearance in each case will only be granted on assurance that the neutrality and sovereignty of Switzerland will be respected during operation of the flight. Diplomatic clearance will not be granted for flights that contravene the rules of public international law, or for flights used in the direct preparation or assistance of hostilities.
The detailed rules and requirements for diplomatic clearance are included in the accompanying document.

Further information

https://www.bazl.admin.ch/content/bazl/en/home/fachleute/flugverkehr/diplomatic-clearances.html