Sorting Out ADS-B

You already have a transponder that transmits a dumb and blind signal in response to interrogation from other sources. Well, its not entirely dumb in that you can enter a four-digit base-eight (no 8s or 9s) code on the instrument and when the transponder responds to an interrogation, it puts that code and even your present altitude (to the nearest 100 feet) onto its outgoing signal. ADS-B Out keeps that but takes it a bit further.

Frank Bowlin

Friday, January 18, 2019 at 12:00 AM ET

Verified

Key Takeaways:

ADS-B (Automatic Dependent Surveillance-Broadcast) is a system where aircraft transmit their GPS-determined position, with "ADS-B Out" being a mandatory requirement for aircraft by 2020.
This basic "ADS-B Out" allows ATC and other ADS-B-equipped aircraft to receive precise position, ID, and altitude data, often relayed by FAA ground stations to overcome line-of-sight limitations.
Optional "ADS-B In" capabilities include TIS-B (Traffic Information System-Broadcast) for receiving comprehensive traffic information, including from radar-identified non-ADS-B aircraft.
Another optional "ADS-B In" feature is FIS-B (Flight Information System-Broadcast), which provides free, ground-based in-flight weather services like NEXRAD, METARs, and TAFs, comparable to commercial satellite options.

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Recently I attended an AOPA Safety Foundation seminar about weather accidents. One big take-away for me was that a large number of the attendees, perhaps the majority, don’t understand ADS-B (which came up, but had nothing to do with the seminar). So, although we’ve run countless articles on various aspects of ADS-B, I felt a responsibility to go over the basics.

I’m going to gloss over some of the details, but this general discussion should prove helpful if you don’t yet quite understand ADS-B.