Heritage Aircraft Owners Seek On-Off ADS-B Exemption


As the ball gets ready to drop on the ADS-B mandate, five owners of a stock 1946 Luscombe are asking for an exemption that would allow them to turn off the ADS-B when they’re outside mandated airspace. The plane is based at busy El Paso Airport and must be able to operate in Class C airspace and it does so now with a battery-powered radio and transponder. To conserve battery power and make sure it’s available when they return to El Paso, the owners turn off the transmitters when they’re out of the zone. The new rules say ADS-B Out must operate continuously regardless of the airspace requirements and the Luscombe owners say that’s not practical for them.

“Right now we can’t equip, because it’s going to cause us to be noncompliant at some point—when the battery dies, or we turn off the [ADS-B] switch,” Jim Ivey, one of the owners, told AOPA. We have decades of experience with a Mode C transponder in the panel; it just comes down to that ‘always on.’” All of the owners have other aircraft but the Luscombe is their fun flyer and the one they use for Young Eagles flights and social events. “We feel like we’re being forced to move the airplane to another airport or sell it,” Ivey said.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. In the UK, they’re about to allow portable ADS-B ‘out’ devices with TSO C199 GPS sources with SBAS and fault detection capability to transmit their position outside of their Rule Airspace. It’s called Electronic Conspicuity. “UK CAA CAP-1391 allows light aircraft, gliders and balloons to see and be seen by other aircraft without equipping with a traditional ADS-B transponder.” The uAvionix SkyEcho EC is one such device.

    See: uavionix.com/skyecho2-caa-cleared/

    With the TSO C199 GPS and a claimed 12 hour battery life, there’s no reason the FAA couldn’t approve use of a portable device like that here in the US for people like these seeking an exemption for a no electrical airplane to egress / ingress our Rule airspace. It would still require a transponder but I’d bet that very low power transponders would help these people to extend the useful time of a battery powered device. I’d rather see an airplane on my ‘in’ box than not.

    In this case, FAA intransigence is being shown up by the UK CAA.

  2. ADS-B OUT is not just there to meet the FAA requirements. It is there to make you visible to all other aircraft. You should be operating ADS-B OUT at all times. The same applies to transponders. The FARs specifically state that if you are transponder equipped it needs to be on at all times.

    What’s the problem with installing a bigger battery? I fly gliders. We have battery powered transponders and don’t have any problem with flying for 5+ hour flights without running out of juice.

  3. As Michael reports, this is not really an issue. An ADS-B Out system comprising a small modern Mode S transponder and GPS position source will run at maybe 0.3 Amp total. A typical small aircraft battery is good for 20+ amp-hours, or up to 60 hours of flight. The “switch it off to save electricity” idea may have been true back when you had a vacuum tube transponder, but those days are gone. There are thousands of aircraft out there – gliders, and no-electrical-system classics – all with radios and ADS-B out transponders that are running from batteries.

  4. I installed “out” in my airplane a while back and only recently bought a portable “in” box. I am blown away by all the things that little box can do. I am now another one of the “believers” in ADS-B. Because I’m activating my hockey puck piece of airspace, I know that the only airplanes I might not see are those without an operating transponder. That’s why I feel strongly that a portable ADS-B “out” box like I described above ought to be allowed in non-Rule airspace within the US.

  5. How long before all airspace becomes ads-b.

    Even after 2020 flights below 10,000 ft msl remain allowed to navigate from border to border and from coast to coast. By January 1, 2020 there will be about 100,000 GA non-complaint aircraft. FAA reported that 60,000 aircraft had complied.

    And BTW, what is ATC’s ads-b functionality?

    • RAF … I predict that the Canadian use of satellite based “ground” stations because of their Country’s large and varying terrain requiring dual diversity transponders will get noticed by FAA bean counters. It’ll be similar to how all the FSS stations we had morphed into just three (I think?). They’ll figure out that they can save $$$ and begin that update in the next decade? Then — as you say — the proliferation of UAMs and drones will necessitate further automation of the NAS and they’ll start increasing the size of “Rule” airspace. Ultimately, I feel, the camel got it’s nose under the tent so the rest is sure to follow … one nibble at a time.

      It ain’t all bad. Earlier today, I was reading up on CAPSTONE in Alaska and saw a stat where 10% of pro pilots flying there would die before reaching 30 years. Now, that’s no longer the case.

      Finally, I’ve been trying to get ATC types to explain what they see on their scopes to indicate ADS-B is working. So far, no luck … even asking AtC types at OSH?

  6. If the aircraft holds 14 gallons of fuel and burns say 3-4 gallons per hour that’s somewhere around 3.5 to 4.7 hours of flight going to the last drop. A “fancy” transponder with a display that does both in and out like the Lynx NGT-9000 (for which I happen to have the install manual and have installed two in our fleet so far) requires 19 watts nominal, 24 watts maximum to operate. This implies at various power demand levels and lengths of flight at 12 volts 5.6 to 9.4 Ah of battery energy should be available to operate the transponder until fuel exhaustion. A 12v SLA battery with a 20Ah capacity weights about 7lb 6oz and would provide roughly twice that capacity even factoring for a higher than C/20 draw. Smaller batteries like this are available. I just happen to have this one sitting around. It measures about 6x6x4 inches.

    To me the easy (and more fun) answer is to install an NGT-9000 which gives you both in and out and is a great transponder and hook it to a battery sufficient to last somewhat more than the anticipated flight. If the main use is in a pattern for rides, one could use a much smaller battery and just swap batteries every few hours of operation.

    Once you get used to ADS-B in, especially in crowded airspace, it’s hard to go backward. It’s better than flight following and really a great addition to the “Mark I” eyeball. People think it is just for warning of traffic but it really lets you look and see “there is no traffic over there, let’s use that airspace” whcih is especially true for local (non-enroute) flights. In that way it allows a certain dynamic kind of “flight planning” or airspace selection you can’t do any other way.