要地防空 meaning in English

essential air defense
point air defense

A threat evaluation model for aerial defense based on grey related theory
基于灰色关联理论的要地防空威胁评估模型
The formulas to be used to calculate the average killed number of targets for one aircraft and the probability that a group aircraft is killed during combat sortie are deduced
在效能指标中反映出与对地攻击靶场效能、对国土防空系统突防效能以及对要地防空系统突防效能的关系。