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) allows aircraft to transmit GPS-determined positions, with ADS-B Out being mandatory by 2020 for enhanced air traffic control and aircraft visibility.
Beyond the mandatory ADS-B Out, the system offers optional "ADS-B In" capabilities: TIS-B for comprehensive traffic information (including non-ADS-B aircraft via ground station relays) and FIS-B for free, ground-based in-flight weather.
Equipping for ADS-B Out requires a permanent, approved WAAS GPS source, and the 2020 deadline is imminent. Considering the integrated benefits of optional ADS-B In features for traffic and weather is highly recommended.

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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.