ADS-B Out
ADS-B Out refers to the component of the system that broadcasts an aircraft’s information to external receivers. This includes not only ground-based ADS-B stations but also other aircraft equipped with ADS-B In. The primary goal of ADS-B Out is to provide real-time situational data to air traffic control and nearby pilots, enabling safer and more efficient operations.
The data transmitted by ADS-B Out includes the aircraft’s GPS-derived position, altitude (both geometric and barometric), velocity, aircraft identification (call sign), and additional information such as emergency status or on-ground indication. This data is broadcast approximately once per second, providing a far more granular and current picture of air traffic than radar-based systems.
Two primary frequencies are used for ADS-B Out transmissions: 1090 MHz Extended Squitter (1090ES) and 978 MHz Universal Access Transceiver (UAT). The 1090ES format is typically used by high-altitude and international aircraft, including commercial airliners, and is based on enhancements to the existing Mode S transponder system. UAT, on the other hand, is designed for general aviation and operates only within the United States below 18,000 feet.
ADS-B Out compliance in the United States is governed by 14 CFR § 91.225 and § 91.227, requiring that aircraft operating in most controlled airspace be equipped with certified ADS-B Out systems. The FAA mandates strict performance requirements, including accuracy and integrity standards, typically met by avionics certified under RTCA DO-260B or DO-282B standards.
Visual Aids
- Illustration of ADS-B Out data elements and broadcast format
- Map showing coverage area of ground stations receiving ADS-B Out
- Flowchart showing aircraft certification and compliance process