ADS-B (Automatic Dependent Surveillance Broadcast)


By: Todd Adams, Lancaster Avionics

ADS-B is the talk of the town nowadays. What do I need? Will the 2020 mandate stick? Who needs it? What changes are coming? And of course...the ‘Biggie’...What does it cost?


My experience on this subject, which goes back to the infancy of a project which started out as the “Capstone Program”, tells me that the biggest hurdle (aside from cost) has been the lack of understanding of how an aircraft owner gets from here to there on equipage. There are plenty of articles telling you what ADS-B is and how it works so I won’t deal heavily with this issue in this article. The purpose of this article is to get down to the ‘Brass Tacks’ of ADS-B. My hope is that I can apply the K.I.S.S. method to provide a basic understanding of what is needed and the pros/cons to your choices. These choices will include portable/uncertified equipment and certified equipment.










Minimum Requirements:

Certified WAAS GPS Receiver

There are not, and most likely will never be, any ADS-B solutions, certified or uncertified that will meet the ADS-B Mandate without a Certified WAAS GPS Receiver for a Type Certificated Aircraft. Exceptions have been made to accommodate the non-certificated aircraft market provided the uncertified equipment meets certain performance characteristics. Your options range from a Panel Mounted WAAS GPS Receiver, to an independent Remote Mounted WAAS GPS Receiver (a.k.a. 'a black box), or a WAAS GPS Receiver that is built in as part of the ADS-B solution (UAT or Transponder).


ADS-B Solution

You have the choice of an ADS-B UAT or a Mode S Transponder with Extended Squitter (ES).  Note:  UAT may be used at any flight level, however, if you intend on flying above 18,000 Ft., out of the country where Mode S is required, OR using the aircraft for Part 135 operations, you must have a MODE S w/ES Transponder whether or not you have an ADS-B UAT.




ADS-B Out vs. ADs-B IN:

ADS-B Out is the ability to transmit a properly formatted ADS-B message from the aircraft to ground stations and to other ADS-B In equipped aircraft.  ADS-B IN is the ability of an aircraft to receive information transmitted from ADS-B ground stations and/or from other aircraft.  ADS-B IN is not mandated by the ADS-B Out rule.  If an operator chooses to voluntarily equip an aircraft with ADS-B IN capability, a compatible display is also necessary to see the information.  Refer to AC20-165A information on ADS-B OUT and AC20-172A information on ADS-B IN installation and certification. A compatible display can be anything from an iPad to a panel mounted display.


The merits of ADS-B are pretty simple.  Assuming the mandate, every aircraft flying within Class B Airspace will need to be, at a minimum, ADS-B Out compliant. The tendency of an owner with an ADS-B OUT only aircraft is to feel that they financed a project for the benefit of everyone else (oh...and to comply with a government mandate).  The part of this mindset that gets lost in the equation is that it is just as important for others to see you as it is for you to see other aircraft.


I will concede that the merits of ADS-B IN outweigh the merits of ADS-B Out.  The frugal side of me dictates that financing a mandate without reaping the total benefit of those funds spent seems like a shame.  The merits of FIS-B Weather, whether through panel-mount or portable means, are pretty self-evident.  FIS-B weather, either as a no-cost back-up to subscription based datalink weather for IFR pilots or as a sole source of weather for the VFR pilot who could never justify the costs of subscription based datalink weather is an added bonus.  TIS-B traffic, either as a blend to existing TAS/TCAS traffic systems or as a sole means of traffic, can only enhance a pilot's awareness of what is around them.  Given the availability of lower cost portable solutions, once certified ADS-B Out equipped, every pilot has the opportunity in one configuration or another, to have something to show for the 'pain of progress'. 


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