Automatic Dependent Surveillance-Broadcast — the name sounds like bureaucratic prose. The system behind it is one of the most significant safety innovations in modern aviation: ADS-B makes every equipped aircraft visible to other aircraft and to air traffic control — more precisely, more currently, and more reliably than any radar.

How ADS-B Works

An ADS-B transponder continuously broadcasts (typically every 0.5 seconds) its own GPS position, altitude, flight path, speed, and identification. This information is received by:

  • ATC ground stations (replaces secondary radar)
  • Other aircraft with ADS-B In (traffic awareness in their own cockpit)
  • Satellite-based receivers (for oceanic areas and regions without ground infrastructure)

ADS-B In vs. ADS-B Out — The Difference

  • ADS-B Out: Mandatory in the EU (since June 7, 2020) and the US (since January 1, 2020). Your aircraft broadcasts its position. ATC and other traffic participants can see you.
  • ADS-B In: Optional (but strongly recommended). Your cockpit receives traffic and weather data from other ADS-B participants. Gives you a complete picture of the airspace.
  • Combination (In + Out): Maximum situational awareness — you see everyone, everyone sees you.

European Mandate: What Has Applied Since 2020?

EASA Regulation (EU) 2017/386 mandates ADS-B Out for all IFR flights in EASA member states — for aircraft with initial certification from 2020 immediately, for older aircraft no later than June 7, 2020. Exceptions apply to certain ultralight and glider aircraft.

In concrete terms: every aircraft operating in controlled airspace needs a Mode S Enhanced Surveillance Transponder + ADS-B Out (1090ES). Retrofit is possible for most aircraft — costs range from EUR 3,000 to 25,000 depending on aircraft type.

Caution when buying pre-owned: Always check whether the aircraft is ADS-B Out compliant. A non-compliant transponder may mean the aircraft can only be operated in uncontrolled airspace under VFR — a significant limitation on utility value.

ADS-B In: The Often Overlooked Safety Benefit

While ADS-B Out is mandatory, ADS-B In is optional — but the real safety benefit lies here. With an ADS-B In receiver, you see in your cockpit:

  • All other ADS-B Out participants in the vicinity (traffic overlay on moving map)
  • FIS-B weather data (in the US): NEXRAD radar, METARs, TAFs — directly on the cockpit display
  • TIS-B traffic (in the US): ATC also relays primary radar contacts
Affordable ADS-B In retrofit solution: Portable receivers like the Garmin GDL 52 or SkyGuard TWX777 can be connected via Bluetooth to an iPad or cockpit EFB. Cost: EUR 500–1,500. This creates at least traffic awareness without any cockpit avionics modification.

The Future: SESAR in Europe, NextGen in the US

ADS-B is the foundation for the next generation of airspace management. In Europe, the program is called SESAR (Single European Sky ATM Research), in the US NextGen. Both initiatives aim for higher-capacity, more efficient, and safer airspace:

  • Precision routing based on continuous position data instead of radar points
  • Closer separation — ADS-B enables tighter spacing at the same safety level
  • Urban Air Mobility (UAM) — eVTOL and drones will be integrated into airspace, ADS-B is the basis for their identification
  • Performance Based Navigation (PBN) — more precise approach procedures (RNP AR) will become standard
What this means for pilots: Airspace will become denser, more digital, and more connected. Those who don't equip their cockpit accordingly will increasingly have to forgo access to certain airspace. Investing in ADS-B In, RNP-capable FMS systems, and current databases is not optional — it's becoming mandatory.

ADS-B is not just another avionics compliance exercise — it's the platform upon which future airspace is being built. Those who buy or retrofit now secure full usability of their aircraft for at least the next decade.

When buying a pre-owned business jet or general aviation aircraft on Airvalon: always check the ADS-B status as the first exclusion criterion — and FMS database currency as the second.