Tracking technology
ADS-B vs Radar: What Is the Difference?
ADS-B and radar can both support aircraft surveillance, but they reach that result in different ways. Understanding the difference helps explain why public flight trackers can have coverage gaps or different update behavior.
By TransitSatellite · Reviewed October 20, 2026
Radar interrogates or reflects radio energy
Traditional radar depends on ground equipment. Primary radar can detect reflected radio energy, while secondary surveillance radar works with aircraft transponders to obtain additional information.
ADS-B broadcasts aircraft-derived information
ADS-B uses a position source aboard the aircraft and broadcasts information to compatible receivers. FAA materials describe ADS-B updates as occurring about once per second, while radar updates can take several seconds.
Coverage still matters
ADS-B does not make receiver geography irrelevant. A ground-based public network still needs suitable reception, and terrain, altitude, equipment, and provider network design affect what users can see.
Common questions
Did ADS-B completely replace radar?
No. ADS-B is a preferred surveillance method in much of the U.S. National Airspace System, but radar and other surveillance systems continue to play roles in aviation.
Why does an aircraft sometimes disappear at low altitude?
Receiver line of sight and terrain can reduce coverage, especially near the ground. Provider filtering or unavailable data can also contribute.
Sources
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