Does European airspace use the metric system?
European Civil Aviation Authorities use the imperial system to depict altitudes and airspace restrictions (feet), speeds (knots) and distances (nautical miles).

Some VFR aircraft have speed indicators in km/h, gliders can have altitude and variometer in meters and meters/second and apart from a special ICAO VFR chart being available in metric in Germany, the AIP itself and all other charts always use imperial units.

Related question: What is the measurement system used in the aviation industry?