I just purchased an aircraft and the prior owner said that I need to put the transponder to my name. What is the procedure to do that?

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    $\begingroup$ Welcome to aviation.SE! Which country are you in? $\endgroup$
    – Pondlife
    Apr 10, 2017 at 12:19
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    $\begingroup$ You need to look the transponder in the eyes and say out loud: "Luke, I am your father". $\endgroup$ Apr 10, 2017 at 13:12
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    $\begingroup$ You'll know if that works if it changes to 7500 @GianniAlessandro. $\endgroup$
    – GdD
    Apr 10, 2017 at 16:45
  • $\begingroup$ If you are talking about a Mode S transponder, the ICAO 24-bit address assigned to it is associated with the aircraft’s registration. When you register your aircraft the Mode S registration is automatically transferred. $\endgroup$
    – JScarry
    Apr 10, 2017 at 16:47
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    $\begingroup$ @JScarry, at registration a 24 bit address is assigned to the aircraft. Depending on the country of registration and whether the aircraft is transferred from the register of a different country, this may or may not be the same 24 bit address that was previously assigned to the aircraft. Therefore the Mode S transponder may need to be recoded with the new 24 bit address after the sale. $\endgroup$
    – DeltaLima
    Apr 10, 2017 at 17:31

2 Answers 2


I assume you have a Mode S transponder. A Mode S transponder uses a unique 24 bit address assigned by the authorities to your aircraft to communicate with Mode S radars. If you do not have a Mode S transponder there is nothing that links your transponder to your aircraft registration.

If you purchase an aircraft you need to register it with the Civil Aviation Authority in your country. With that registration you will get a 24 bit address (in some countries you will always get it, in others you need to indicate that you have a Mode S transponder). The 24 bit address is usually given as a hexadecimal string of six characters, some countries use a 8 character octal representation. This code needs to be programmed in your transponder. It may be that the 24 bit address is the same as it was before. In that case nothing has to be done on the transponder.

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    $\begingroup$ In particular, in the U.S. the 24-bit address is deterministically derived from the N-number, so if the N-number doesn't change then the transponder doesn't need reconfiguring. That's not the case in all (maybe even most) countries. $\endgroup$ Apr 11, 2017 at 5:35

Standard practice or procedures involve the aircraft to be Register reserving their aircraft registration And also requesting their 24 bit or 6 Alfa numeric combination of 0 1 2 3 4 5 6 7 8 9 A B C D E and F into their physical transponder which the first 3 character is Country code and remaining 3 aircraft specific. Example 8960F1 where 896 is country for United Arab Emirates and 0F1 aircraft assignment.


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