자동 종속 감시-방송 (ADS-B) (Automatic Dependent Surveillance-Broadcast)

What Is ADS-B?

Automatic Dependent Surveillance-Broadcast (ADS-B) is a next-generation surveillance system in which aircraft automatically transmit their GPS-derived position, altitude, groundspeed, heading, and ICAO address without any interrogation from the ground. Unlike traditional radar — which must rotate and interrogate aircraft — ADS-B provides continuous, high-update-rate position data to ATC ground stations (ADS-B Out) and to other equipped aircraft (ADS-B In, enabling traffic awareness on the flight deck).

How It Works

An ADS-B Out system consists of a GPS receiver, a Mode S transponder with 1090 MHz Extended Squitter capability, and an approved GPS/SBAS antenna. The transponder broadcasts an ADS-B message approximately twice per second containing:

• ICAO 24-bit address: Unique aircraft identifier
• GPS position: Latitude and longitude with accuracy indicators (NACp, NACv)
• Barometric and geometric altitude
• Groundspeed and track angle
• Emergency status and flight ID

Ground stations forward received ADS-B reports to ATC displays, replacing or supplementing traditional radar. ADS-B In receivers on the flight deck display TCAS-style traffic on moving maps, and can receive FIS-B (weather uplink) and TIS-B (radar-derived traffic for non-ADS-B aircraft) in the US. Over oceanic airspace — where no radar coverage exists — ADS-B enables reduced separation standards from 80 nm to as low as 15 nm.

Evolution and Modern Systems

ADS-B was first deployed in Alaska in the early 2000s. Australia's Airservices deployed a nationwide ADS-B network, replacing much of its radar infrastructure. The FAA's NextGen program mandated ADS-B Out by January 1, 2020 for most controlled US airspace. Iridium-based space ADS-B (Aireon) provides global oceanic coverage from low-Earth orbit satellites, enabling real-time tracking of transatlantic and transpacific flights for the first time.

Regulatory Requirements

FAA FAR 91.225/91.227 mandate ADS-B Out meeting DO-260B performance standards in Class A, B, C airspace and above 10,000 ft MSL. EASA mandates ADS-B Out from June 2020 for aircraft over 5,700 kg or faster than 250 knots operating in European airspace. Position accuracy requirements: NACp ≥ 9 (horizontal accuracy within 30 m), NACv ≥ 1 (velocity accuracy within 10 m/s).