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


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.