Nader VEDADIAN - Senior A/C Engineer (Avionics)، The Airline of the Islamic Republic of Iran

ATC Mode-S system has been mandatory according to the regulations established by ICAG from 1999. This article describes A TC Mode-S operation, capabilities, uplink & downlink formats, SSR ground (Mode-S), interrogations,ground controlers & surveillance, optimized surveillance in Elementary & Enhanced projects. In Elementary & Enhanced projects, many very usefull data will be transmitted to ground in order to achieve much more safety and control. This article explains how the optimized surveillance is to be performed