# How do I know if a Transponder is compatible with ADS-B

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#### mcurcio1989

##### Well-Known Member
I don't even know if that is the right way to ask this question or not but here is what I am looking to do. I have two airplanes and neither have transponders.

First plane is an Aventura 2 Amphib. This obviously isn't a cross country machine and I don't fly into any airspace where a transponder is required. One exception to that is Mode C veil - I would really like to be able to fly into Detroit and Chicago's mode C veils. I would like to get basically the cheapest used transponder I can find that will allow me in a few years to ad ADS-B out if I decided to.

Second plane is a Quickie Q200. I just picked this up as a sort of project. It has 230 hours on it but hadn't been flown in a while and needed a bit of a facelift. The PO never had any electronics - not even lights or a transceiver. This is obviously a cross country machine so I definitely need the transponde. I again want to get into a inexpensive used transponder and I will be adding ADS-B out in a year or two.

The issue is as I am looking at used transponders it is very hard to determine which ones will be compatible with ADS-B out. Looking for any advice on hoe to take care of this without braking the bank.

#### TFF

##### Well-Known Member
The easiest transponders are the Mode S transponders. They already have the 1090 guts shall we say. There are ADSB 978 boxed that can use the Mode C transponders and some how modify the signals if you don't have a Mode S. The FAA actually wants more acceptance of the 978 because of the need for 1090 for IFR traffic. The hash, of does it need it or not, rears its ugly head. If you fly in Class E airspace you have to have a transponder if plane has an electrical system. Class E is considered Controlled Airspace. The notion of talking to the tower only constitutes controlled is wrong. The only uncontrolled airspace in the US is G.

#### Aerowerx

##### Well-Known Member
Call the company that made it?

Google for an on-line copy of the manual?

Look on-line for a list of FAA approved equipment?

#### Paulie

##### Well-Known Member
The manufacturer specifics will indicate if ads-b out capable, and it will not be cheap.

#### Dana

##### Super Moderator
Staff member
If you fly in Class E airspace you have to have a transponder if plane has an electrical system. Class E is considered Controlled Airspace. The notion of talking to the tower only constitutes controlled is wrong. The only uncontrolled airspace in the US is G.
I don't think that's correct; as far as I know a transponder (and soon, ADS-B out) is required in B, C, and the mode C veil under B, but not in E.

-Dana

#### mcurcio1989

##### Well-Known Member
f you fly in Class E airspace you have to have a transponder if plane has an electrical system. Class E is considered Controlled Airspace. The notion of talking to the tower only constitutes controlled is wrong. The only uncontrolled airspace in the US is G.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.215

See Link above. I don't believe that is a true statement unless I am reading something wrong. You need a transponder to fly in class E above 10,000 feet, otherwise its just A, B, C and the mode C veil.

This is from the FAA's website regarding pilots who elect not to equip with a transponder:

If I fly in airspace that does not require a transponder today, will I still be able to fly there without ADS-B Out?

For the most part, ADS-B Out will be required in the same airspace where transponders are required. However, to be sure of the regulatory requirements it is best to check 14 CFR § 91.225 for ADS-B-designated airspace and 14 CFR § 91.215 for transponder-designated airspace.

Anyways - I have looked online for a list of approved equipment but it isn't even that easy because experimental's don't need approved out equipment anymore as I understand it. I guess I may just leave the amphib without a transponder and equip the quickie.

What gets me is all of these different encoders, gps's, antenna's etc. I wish someone could just say - if you are building a cross country airplane and dont have anything to start from just get -"this". I understand there are loads of factors as far as what talks to what that make it confusing.

My problem is that I am not an electronics guy and the club I learned to fly in is old school. Our joke is that are members can't spell GPS but can hand prop expertly. I just haven't been around long enough or exposed to any of the electronics side of aviating.

#### Paulie

##### Well-Known Member
For experimental I feel the best solution is the uavionix echouat. It is comparable with some legacy mode c transponders. $1000. If approved GPS is required they have one at$500. This may seem expensive but is the best solution in my opinion.

#### TFF

##### Well-Known Member
You have to have a transponder in A, B,C no matter what. If you have an electrical system by default you have to now have it in D and E. No electrical can fly into towered D airports without any but regular talk to the controller, where to fly non transponder into B,C require prior request and acceptance. I have heard of nice controllers not being picky as its on their prerogative. Now it is hard to get caught flying no transponder if you stay away from populations. Where it is going to change is pilots will start complaining they don't see you on their ADSB traffic alerts. The holdouts will be easier to find.

#### mcurcio1989

##### Well-Known Member
Not to pick on you but I would really appreciate it if people would support these kinds of claims with FAR's. There is no reason to speculate on this stuff. The FAR's are readily available and are clear and concise. I have never seen what you are saying anywhere in a FAR or in any type of news release. This is the problem with internet forums. Now some neophyte is going to read that and assume it is true because you have 8,000 post on here. I'm very interested if what you are saying is true but I am not going to believe it until I see a FAR or FAA news release that says so. I have provided links for the FARs that support what I am saying below.

The current rules for transponder use are found at this link:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.215

The FAA sates the following:

For the most part, ADS-B Out will be required in the same airspace where transponders are required. However, to be sure of the regulatory requirements it is best to check 14 CFR § 91.225 for ADS-B-designated airspace and 14 CFR § 91.215 for transponder-designated airspace

Below is the official FAR regarding ADS-B out usage requirements (91.225):

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/00960eb5897eed7c8625775800671304!OpenDocument

As is the case with mode C, above 10k feet ADS-B is required in class E. The only difference is that above 3k feet in the gulf of Mexico it is also required in class E.

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#### 12notes

##### Well-Known Member
Log Member
You don't need a transponder in class D airspace even if you have an engine-driven electrical system, and you only need one in class E if you have an engine-driven electrical system and are either above the ceiling of a Class B or C, or are both over 10,000 feet MSL and 2,500 AGL. Class D is never even mentioned in the transponder required areas of the rules linked above.

#### TFF

##### Well-Known Member
How do you get out of section b(3)?

#### 12notes

##### Well-Known Member
Log Member
How do you get out of section b(3)?
That is the section that specifically allows aircraft without electrical systems to operate without a transponder inside of a mode C veil as long it remains outside of class A,B,C airspace and doesn't go over the class B or C ceiling. I think you might have missed that that's a permissive, not restrictive, section, in the middle of a bunch of restrictions, and not relevant to planes with electrical systems.
Understandable, since the rule is structured:
Rule 1 - Never go here
Rule 2 - Especially not here
Rule 3 - If you don't have a thing, or never had the thing, you can go to the especially not here area, but still not the original never here area.
Rule 4 - Never go here either
Rule 5 - A brand new, more complicated never go here area, but with an exception for never having the thing in the rule.

#### TFF

##### Well-Known Member
I read it as the freedom with no electrical and the death sentence for electrical.

#### BBerson

##### Well-Known Member
HBA Supporter
Probably best to buy a new ADS-B with the proper transponder module. (extra \$500)
EAA has a webinar archive from a few months ago with much details.
Another webinar update scheduled in July, I think. ((Paul Shuch sp?)

#### Direct C51

##### Well-Known Member
I know this forum is primarily for builders and designers, and secondary for pilots, but come on guys. Mode C transponder requirements are like week one private pilot stuff. I get questions about ADS-B requirements which are new and have been evolving. 91.215 is very clear. Mode C required for A, B, C, mode C veil, above B or C, and above 10,000. TFF - just stop. You are spreading blatantly false information.