Mode "A" Transponders

[Tom-D]

When pinged, the Mode "S" will give N Number and other normal info. ?

How is that changed when a Mode "S" transponder is changed from one aircraft to an other?

 

[MarkG]

It really depends on the transponder type. Generally it will be one of two methods. Most of the GA transponders such as Garmins 330's you enter the maint menu and have to reset the N number and oct or hex code. In the corp jets with such as the TDR94 series and Honeywells, it is generally done with programming pins or modules at the back of the rack plug. That way the units are plug n play and you don't have to worry about re-programming, unless you want to change the N number of the aircraft.

 

[Silvaire]

As said above that info is hardwired on the aircraft, when it comes to GA, I don't even know anyone who has a mode S (yet) That will change come 2020 though.

 

[John Collins]

With the GTX330, you enter either the N number or the Octal code for a US registry aircraft. They two are related by an algorithm, so setting one causes the other to be adjusted accordingly.

 

[Bob Noel]

As said above that info is hardwired on the aircraft, when it comes to GA, I don't even know anyone who has a mode S (yet) That will change come 2020 though.

eh? why will 2020 change anything wrt mode S? note that ADS-B doesn't require mode S.

 

[BillTIZ]

As said above that info is hardwired on the aircraft, when it comes to GA, I don't even know anyone who has a mode S (yet) That will change come 2020 though.

Mode S has been out for years.
Look up the N number in the FAA data base, you will find the code to load into the transponder. If you swap transponders, any radio shop can reset the code to the new aircraft. Plus changing transponders requires a new 91.411, 91.413 checks.

 

[Tom-D]

Mode S has been out for years.
Look up the N number in the FAA data base, you will find the code to load into the transponder. If you swap transponders, any radio shop can reset the code to the new aircraft. Plus changing transponders requires a new 91.411, 91.413 checks.

Finally got an answer. Thanks.

I didn't know the transponder could be keyed at the shop.

 

[denverpilot]

Finally got an answer. Thanks.

I didn't know the transponder could be keyed at the shop.

Not only can be, must be. Otherwise it'll be blabbing away on the manufacturer's default code.

 

[Tom-D]

Not only can be, must be. Otherwise it'll be blabbing away on the manufacturer's default code.

To me that's a good thing.

 

[kontiki]

When pinged, the Mode "S" will give N Number and other normal info. ?

How is that changed when a Mode "S" transponder is changed from one aircraft to an other?

Mode S Transponders also squit every sec or so. Its a pseudo randomly timed broadcast with alt & Mode s address.

 

[kontiki]

Mode S has been out for years.
Look up the N number in the FAA data base, you will find the code to load into the transponder. If you swap transponders, any radio shop can reset the code to the new aircraft. Plus changing transponders requires a new 91.411, 91.413 checks.

Not true, FARS actually say transponder must be checked and give you option of doing it on wing. Some airlines meet the req by just pulling the units and testing at bench.

 

[flyingron]

You can't test mode S transponder's exclusively on the bench. The tests require the antenna in the circuit.

 

[John Collins]

You can't test mode S transponder's exclusively on the bench. The tests require the antenna in the circuit.

This is not correct. There is a conditional requirement to perform the encoder correspondence test for any transponder that supports mode C or S if "data correspondence error could be introduced". Simply removing and replacing the same make and model transponder does not introduce data correspondence error, unless you break the static air source to the encoder, which you would have no need to do.

91.413(b) Following any installation or maintenance on an ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), appendix E, of part 43 of this chapter.

Part 43 Appendix F clearly states (emphasis mine):

The ATC transponder tests required by Sec. 91.413 of this chapter may be conducted using a bench check or portable test equipment and must meet the requirements prescribed in paragraphs (a) through (j) of this appendix.

 

[John Collins]

Mode S has been out for years.
Look up the N number in the FAA data base, you will find the code to load into the transponder. If you swap transponders, any radio shop can reset the code to the new aircraft. Plus changing transponders requires a new 91.411, 91.413 checks.

On a GTX330 it is extremely simple, you don't need to know the transponder code, just enter maintenance mode and enter the N number and it figures out the transponder code. The procedure is documented in the install manual. BTW, the A/C registration form has the transponder code printed on it, whether you have a mode S installed in your aircraft or not.

You do not need to do a new 91.411 or 91.413 check if you remove, repair or replace the transponder with one of the same make and model, as long as the replacement transponder has been bench checked IAW 91.413 and has an appropriate yellow tag (form 8130). If you make wiring changes or break the static line, then you would need to perform 91.411 (c) and should perform a system test.

If the N number is not loaded into the transponder, it will transmit all zero's and the first time the aircraft is detected by radar, you will end up getting a letter from the FAA to take care of it.

Where it gets murky is when you change the N number and don't remember to update the transponder code. Updating the mode S code and the 406 ELT information should be on the check list of any change to the N number.

 

[JHW]

so in a nutshell, when we someday get enroute user fees you'll want to use that mode on your transponder to enter the N-number of that loudmouth neighbor at oshkosh that set a beer can on your wing ?

 

[John Collins]

so in a nutshell, when we someday get enroute user fees you'll want to use that mode on your transponder to enter the N-number of that loudmouth neighbor at oshkosh that set a beer can on your wing ?

Sounds reasonable to me!

 

[kontiki]

You can't test mode S transponder's exclusively on the bench. The tests require the antenna in the circuit.

Not what the FAR says. It's silly to argue facts, just look it up.