FAA Clarifies ADS-B Mandate For Non-Electrical Aircraft

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The FAA has clarified the upcoming ADS-B Out rules regarding aircraft without electrical systems, elaborating on the current FARs regarding transponders. The ADS-B rule, which takes effect on Jan. 1, 2020, to mandate position-reporting equipment in airspace where transponders are now required, will not apply to “aircraft originally certificated without an electrical system but which have subsequently had batteries or electric starters installed,” the FAA said in its recent letter of interpretation (PDF). This exemption includes many models of vintage airplanes, along with balloons and gliders. The letter clarifies questions about what defines non-electrical aircraft and states that those “would not be required to equip for ADS-B Out.” According to an AOPA report, the interpretation clarifies that those aircraft now exempt from having transponders to fly in areas including beneath classes B and C airspace will still be exempt when the ADS-B Out equipment rule goes live.

“The concern was that the exception expanded the types of aircraft required to equip with ADS-B Out beyond those required to equip with a transponder,” said Justin Barkowski, AOPA director of regulatory affairs. “AOPA has received several inquiries about what types of aircraft fall within this exception, and has been tracking this issue with the FAA for some time now. This is a favorable interpretation.” Part of the confusion stemmed from the FAA’s wording in the transponder regs that mention aircraft “not originally certificated with an engine-driven electrical system,” and the reg for ADS-B Out, which exempts “aircraft that was not originally certificated with an electrical system.” The agency indicates in its letter that it “may consider a technical amendment in the future to remove any confusion” between the two phrases.

Comments (3)

... instead of allowing hand-held ADS-B out equipment, which would of course lower the cost of ADS-B out for everyone. Which of course will happen when ADS-B out is required in drones as they become more advanced and capable. Which (as per usual) makes too much sense for stubborn bureaucrats...

Posted by: Peter Kuhns | January 30, 2017 7:03 AM    Report this comment

There are technical reasons why handheld or portable ADS-B Out equipment isn't workable from a safety standpoint. One of the major problems with a temporary installation is the antenna positioning and coverage (radio emission pattern). Antennas inside the aircraft will suffer shielding by various parts of the airframe structure. As the aircraft attitude changes, nulls (that is, dropouts of the transmitted signal strength) will occur and can prevent the ADS-B ground stations and other aircraft from receiving the ADS-B squitter or reply. Obviously, this can present a safety hazard in that the aircraft will be invisible to ATC and other aircraft during those times. Another factor is the static source input to the ADS-B altitude encoder. A portable system will have to be attached to the aircraft static system for the pressure altitude to be accurate (an internal static source will read a lower pressure (thus a higher altitude) than that at the airframe surface). Other potential problems include reliability of powering (a temporary power connection is easily broken compared to a hardwired installed system for example), and misconfiguration of the ADS-B transponder or UAT. There are valid technical reasons, not everything in aviation is "making too much sense for stubborn bureaucrats". I was a technical consultant to the ADS-B ground segment prime contractor, believe me, there is much more to ADS-B than what you see on the surface.

Michael, Ph.D., P.E., Consulting Communications Engineer

Posted by: BARNET SCHMIDT | January 30, 2017 4:20 PM    Report this comment

If a non-TSO'd ADS-B unit meets the requirements when installed in any experimental or Light Sport aircraft, why won't the FAA allow the installation in certificated aircrat? I agree with Peter Kunn's comment about stubborn bureacrats. The FAA is "ate up" with lawyers and that is the main problem.

Posted by: Richard Warner | February 1, 2017 11:18 AM    Report this comment

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