Automatic Dependent Surveillance Broadcast (ADS-B) is a key component of the Next Generation Air Transportation System (NextGen) – the transition from ground-based-radar air traffic control to an automated transmission of precise aircraft position based on Global Positioning System data.
ADS-B Out is a new way for air traffic control to separate air traffic that doesn’t rely on radar - allows for tighter aircraft spacing and higher traffic capacity in congested airspace. GPS is a key component of ADS-B Out providing highly accurate and reliable position information. Aircraft flying in ADS-B Out airspace use GPS to determine its position and automatically transmit it - these position rep reports are significantly more accurate and update more quickly than radar.