eeldefineeritud piiridega õhuruumiosad, mille sees toimuv tegevus nõuab asjaomase õhuruumi reserveerimist etteantud ajaks teatud kasutajate tegevuseks., an airspace temporarily reserved and allocated for the specific use of a particular user during a determined period of time and through which other traffic may be allowed to transit under air traffic control (ATC) clearance, a defined volume of airspace normally under the jurisdiction of one aviation authority and temporarily reserved, by common agreement, for the specific use by another aviation authority and through which other traffic may be allowed to transit, under ATC clearance