What is the difference between ACARS and ADS-B?

For weather information in-flight or pre-flight which one is used?

  • 2
    $\begingroup$ They're two separate protocols. ADS-B is used for transponder reporting and TCAS; ACARS is for relaying information from the company (airline) to pilots. $\endgroup$
    – verandaguy
    Nov 18, 2019 at 16:01
  • $\begingroup$ Are you referring to FIS-B, rather than ADS-B? $\endgroup$
    – StephenS
    Nov 18, 2019 at 16:41
  • $\begingroup$ You may add your current understanding of both systems so that we can adapt the answer to address the points unclear to you. $\endgroup$
    – Manu H
    Nov 19, 2019 at 7:50

1 Answer 1


One can easily get lost in the alphabet soup that is datalink.

Both ACARS and ADS-B provide datalink applications – which can be broken down in terms of CNS: Communication, Navigation, and Surveillance.

  • ACARS is used for:

    • Communication: includes uplinking (ground → aircraft) weather data upon a downlink request to the company/service provider – not a public service
    • Navigation: if you consider flex-routing
    • Surveillance: position reports in the North Atlantic for example (CPDLC over ACARS).
  • ADS-B is used solely for Surveillance; broadcasting (OUT) own location – and can include ownship surveillance by receiving (IN) traffic information.

    • If this IN setup is via the UAT frequency, then the aircraft can also receive weather information using FIS-B (free service). Its only relation to ADS-B in this particular instance is the UAT frequency, and it is more of a general aviation (and low-flying commercial) service.

enter image description here
Source: https://www.faa.gov/nextgen/programs/adsb/pilot/#fisb


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .