### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### PatrickW

##### Well-Known Member
I live in the country and never fly into a Mode-C veil, or into Class C, or anywhere else where ADSB-Out is required.

But I'd like to have the option of visiting friends who live at airparks which are within a Mode-C veil, so I'd need ADSB-Out to do that.

I don't want to permanently install ADSB-Out into either of my homebuilts (one is flying now, another is under construction, and third kit is paid for and I'll pick it up in about 6 months).

Is there such a thing as a portable ADSB-Out? Something that I could buy once, and then use in whichever plane I'm flying at that time? That sounds like it would be an ideal solution for guys like me.

Thanks,

- Pat

#### spaschke

##### Well-Known Member
No such thing that is legal. FAA requires it to be installed and not portable. Ads-b is airplane specific, even though the code can be changed in the settings.

#### TFF

##### Well-Known Member
Not legal to remove once you put it in. To move it around would require reprogramming each time, which is a hassle in its self. Honest mistakes, the FAA sends nasty grams, I would not want to get caught, flat breaking the rules.

#### proppastie

##### Well-Known Member
Supporting Member
To move it around would require reprogramming each time,
as we get old we forget things....I know I can access my Skybeacon from my phone app so if changing the N# and ICAO is possible with that (I can not remember) I would not find that so bad and it is only 2 screws and 2 wires same as the position light is replaces....I also can not remember if I gave my N# to the company or not and it is certainly a little pricey for an occasional flight.... The experimental version is less expensive though and one might be able to play more and go more places with the airplane if it is installed, if a portable was out there it probably would cost just as much....it really is easy to install unless the problem is you do not have a transponder too.

#### GeeZee

##### Well-Known Member
Proppastie, what you are suggesting might work. What you are doing is uninstalling/ installing an ADSB system. That‘s not a portable ADSB system.
You would want a separate PAPR report for each aircraft. As long as you stay in the the mode C veil you don’t need to talk to anyone and can run in anonymous mode so “the man” wouldn’t even know which aircraft was using the equipment. You might be getting into a grey area if you wanted to fly either A/C without ADSB.

#### proppastie

##### Well-Known Member
Supporting Member
I would think one would just install it on one aircraft and only use that aircraft with ADSB to visit friends in the mode C areas.....but if you have more than one aircraft I would think you could have more than one ADSB

#### GeeZee

##### Well-Known Member
Well sure you can have as many as you can afford…
I just meant that there is some wording in the rule that says you can’t turn ”off” an installed system. I think there is still some speculation that that intent could be interpreted to mean that you can’t uninstall a system for “convenience”. I don’t recall reading any details about uninstalling a system so can’t really say.

#### Jay Kempf

##### Curmudgeon in Training (CIT)
Supporting Member
If you are the repairman for your machine you can use the experimental version of Uavionix. Those last time I checked were about $800. The certified version is about$2k plus A&P fees. Simple install and setup with a cell phone app. It just rebroadcasts your current transponder settings and then output in the correct format. If you are the repairman on several aircraft I can't imagine that you couldn't move one from one to the other to the other (2 screws and 2 crimp connections) with the appropriate log entries...

#### TFF

##### Well-Known Member
Moving to another airplane would be a hassle the way things should be mounted. You could leave everything flopping on the floor like I did with a cheap car stereo in high school, but that’s not aviation. Most of the ADSB boxes are not tray mounted, it’s unbolting and bolting. You have to use the Uavionix to be able to program. Most other brands require service centers to program.

Another take is equip one for visits and the other is for other places. If your going to visit what plane should not matter much if you got two. Pitch the one that makes the most sense to fly in.

To me ADSB isn’t going to save situational awareness for people unaware. The recent midair of the Cessnas prove that. I had a Barron that was IFR try and get as close as possible at about 9000 ft because we were in his way and he was hedging his heading. It was clear and we were on flight following, so we are both talking to the same controller. We could see what he was doing but the controller was having a fit because all he has is the screen. No way the Barron had less equipment than us and we were watching him both on the screen and out the window. He could see us too but it was not to his advantage to acknowledge it.

ADSB in will help let you avoid others even if you are not out, and how many non ADSB planes are out there that you are always around without incident. Side note is the less fancy systems paint fewer target. The closest ones get squawked. There could be a dozen airplanes just outside but not enough memory to keep up. Depends on multiple things.

#### FinnFlyer

##### Well-Known Member
The issue is the required transponder check. The test equipment is unfortunately much more expensive that ADSB out in your aircraft and also requires re-calibration, probably yearly.

Finn

#### Vigilant1

##### Well-Known Member
Supporting Member
Unless things have changed, you don't need a transponder when flying within the Mode C veil if you call the facility controlling the airspace in advance by telephone. They'll give you a code to mention to the controllers when you make radio contact.
It's not guaranteed everywhere all the time.

#### Pops

##### Well-Known Member
Supporting Member
Don’t need a transponder for mode c veil if aircraft never had an engine driven electrical system.
Doesn't it say " certified with an engine driven electrical system ? If so, homebuilts are not certified.

#### BBerson

##### Light Plane Philosopher
Supporting Member
Homebuilt’s have a special airworthiness certificate.

Staff member

#### wildhorsesracing

##### Well-Known Member
Supporting Member
I fly a Hatz biplane using a Stratux for ADSB-In on my Android phone with iFly GPS.

I recently installed ADSB-Out on my Hatz a couple of weeks ago, it didn't have a transponder so I purchased the Stratus ES with the associated wiring harness, encoder and antenna.

I primarily purchased ADSB-Out because I left a local Fly-In and a Pilatus was headed directly at me, I could see him on my phone and eventually after diverting to a lower altitude watched him fly over me. I am assuming he didn't know I was there because I didn't have a transponder or ADSB-out and was busy getting to the Fly-In (ie. staring at his glass panel).

I will also mention that I installed the uAvionix wingtip ADSB-Out in my Cessna 172 and forgot to turn on the Nav lights (old habits die hard) for the 1st 10 hrs or so. I was flying in daylight and was primarily in an empty pattern to test out the restoration we did on the Cessna and was focused on testing other things so the Nav lights were far from my mind. I have the switch in the on position all the time now.

#### SpruceForest

##### Well-Known Member
The issue is the required transponder check. The test equipment is unfortunately much more expensive that ADSB out in your aircraft and also requires re-calibration, probably yearly.

Finn
The ADS-B specific check is the post-install flight check... once that is completed successfully, no specific check on the ADS-B system beyond turning on and seeing if it throws a failure flag or code. The 24 month requirement is for an installed transponder, whether ADS-B-capable or not, and that check is largely a legacy requirement related to older cavity tube xpdrs that had predictable indication of failure on test. If your older transponder passes the test, it will almost certainly run at least 24 months without issue, and the reg reflects that reality.

The last century thinking was that aircraft that flew a lot were likely 135, so would eventually be forced to go Mode S when their analog transponder became non-repairable or at end of regulatory life, and it was unlikely that most other non-commercial aircraft would accumulate enough hours between checks to see an in-flight failure. That requirement would have been written out of the regs with the 1990's Mode S mandate, but common sense prevailed on the mandate and GA got a pass in exchange for 24 month checks forevah... or at least when a non-transponder-dependent air transport TCAS results in 100% fleet equipage.

Modern digital systems (like all transponders) are still subject to that 24 month check if not already covered under a CA program, but they actually run self-test every time they power up, making the transponder check largely pro forma. These newer boxes run about 3-5 times longer between failures than the analog cavity tube units they replaced (8K-10K hours for GA systems and closer to 20K hours for air transport). Last time I looked at estimated failures (this was about 2018, so pre-mandate), the aggregate GA number was IMS, about 1800 per year and air transport was about 0.3 per year (about 40 months between failures in the NAS for air transport due to default dual transponder equipage). Because 1090ES solutions were packaged with transponders and UAT were generally stand-alone units, post-mandate failure numbers pretty much reflected the remaining supply of older, lower time-between-failure transponders in the fleet segment not equipping with 1090ES ADS-B and the fleet segment that went UAT.

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#### FinnFlyer

##### Well-Known Member
The ADS-B specific check is the post-install flight check... once that is completed successfully, no specific check on the ADS-B system beyond turning on and seeing if it throws a failure flag or code. The 24 month requirement is for an installed transponder, whether ADS-B-capable or not, and that check is largely a legacy requirement related to older cavity tube xpdrs that had predictable indication of failure on test. If your older transponder passes the test, it will almost certainly run at least 24 months without issue, and the reg reflects that reality.

The last century thinking was that aircraft that flew a lot were likely 135, so would eventually be forced to go Mode S when their analog transponder became non-repairable or at end of regulatory life, and it was unlikely that most other non-commercial aircraft would accumulate enough hours between checks to see an in-flight failure. That requirement would have been written out of the regs with the 1990's Mode S mandate, but common sense prevailed on the mandate and GA got a pass in exchange for 24 month checks forevah... or at least when a non-transponder-dependent air transport TCAS results in 100% fleet equipage.

Modern digital systems (like all transponders) are still subject to that 24 month check if not already covered under a CA program, but they actually run self-test every time they power up, making the transponder check largely pro forma. These newer boxes run about 3-5 times longer between failures than the analog cavity tube units they replaced (8K-10K hours for GA systems and closer to 20K hours for air transport). Last time I looked at estimated failures (this was about 2018, so pre-mandate), the aggregate GA number was IMS, about 1800 per year and air transport was about 0.3 per year (about 40 months between failures in the NAS for air transport due to default dual transponder equipage). Because 1090ES solutions were packaged with transponders and UAT were generally stand-alone units, post-mandate failure numbers pretty much reflected the remaining supply of older, lower time-between-failure transponders in the fleet segment not equipping with 1090ES ADS-B and the fleet segment that went UAT.
Doesn't change the fact that 24 month transponder check is legally required. Note that includes the static system so is aircraft-specific. I guess if you can get your avionics guy to check the system in both airplanes I guess it could be legal.

Finn