目前，GNSS增强系统主要有ABAS、GBAS、SBAS和GRAS。（

相关题目

• Single GLS can serves all runway ends and in one airports.（
• The GBAS channel range is restricted to （ ） so that the chan
• The GLS System eliminates need for “critical areas ” required fo
• The GLS System eliminates need for “critical areas ” required fo
• Single GLS can serves all （ ）and in some cases multiple airp