Subchapter 9.6 – Block Airspace and Traffic Restrictions

Handling blocked airspace:

Check NOTAMs before flight planning. Do not request clearance to an altitude or route through blocked airspace.
Plan an alternate route or altitude that avoids the blocked area.
If cleared through or near blocked airspace by mistake, inform ATC immediately: "Zurich Approach, HB-CDA, we are cleared Flight Level 180, but Flight Level 180 is blocked airspace. Request Flight Level 150."

ATC will immediately reissue your clearance.

Report any incursion into blocked airspace to ATC immediately after exiting. An accidental incursion is reportable to authorities but is forgiven if you notify ATC at once. Unreported violations are more serious.