Air Traffic Management Concept Baseline Definition - The Boeing ...

standardized as VDL Mode-4. Both systems will require ground stations for air-ground
surveillance, and are being considered for reduced cost air-ground surveillance and for airair
applications such as collision avoidance and Cockpit Display of Traffic Information
(CDTI).
Row 11 in Table A-6 describes Mode-S Services. This sensor is a potential domestic form
of ADS that would use interrogation by the Mode-S radars to downlink surveillance data
such as aircraft position and velocity states and intent information. Mode-S Services is
complementary to extended squitter based ADS-B and is considered to be a transitional
system between the current radar systems and a fully integrated radar/ADS-B surveillance
system.
Row 12 in Table A-6 describes Traffic Information Services (TIS) or TIS broadcast. This
is the concept of transmitting ground based track information to equipped aircraft for
providing air-air surveillance on nearby aircraft. This type of service can be implemented
using the Mode-S interrogation band, or using another communication system such as
VDL Mode-4. This service is intended as a lower cost means of surveillance than TCAS
systems, and as a transitional or backup service to using ADS-B for air-air surveillance.
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