Should I switch the transponder to STBY or not while changing codes?











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I´m now reading Bob Gardner’s book “Say again, please” and there is this instruction on page 54: “Do not turn the transponder function switch to STBY while changing codes.”



What is the reason for this? I’m a PPL student and my instructor told me the opposite.






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    up vote
    8
    down vote

    favorite












    I´m now reading Bob Gardner’s book “Say again, please” and there is this instruction on page 54: “Do not turn the transponder function switch to STBY while changing codes.”



    What is the reason for this? I’m a PPL student and my instructor told me the opposite.






    transponder







    share|improve this question









    New contributor




    Hask Somatotoian is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






















      up vote
      8
      down vote

      favorite









      up vote
      8
      down vote

      favorite











      I´m now reading Bob Gardner’s book “Say again, please” and there is this instruction on page 54: “Do not turn the transponder function switch to STBY while changing codes.”



      What is the reason for this? I’m a PPL student and my instructor told me the opposite.






      transponder







      share|improve this question









      New contributor




      Hask Somatotoian is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      I´m now reading Bob Gardner’s book “Say again, please” and there is this instruction on page 54: “Do not turn the transponder function switch to STBY while changing codes.”



      What is the reason for this? I’m a PPL student and my instructor told me the opposite.






      transponder




      transponder






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      Hask Somatotoian is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      share|improve this question









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      Hask Somatotoian is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      share|improve this question




      share|improve this question








      edited 2 hours ago









      Pondlife

      50k8134274




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          2 Answers
          2






          active

          oldest

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          up vote
          10
          down vote













          The FAA started advocating not selecting standby for code changes after it was found that more often than one would expect, the transponder doesn't always come back on after standby. Seems they uncovered a number of switch failures.



          I figure that someone decided that for TCAS it was better to have a transponder squawking any code than not squawking. But that is my own conjecture.



          So for quite a few years the guidance has been to not turn to standby when selecting codes.



          I have had the folks at Flight Safety lecture me after sim sessions, with pretty much the same story.



          So I now teach students to just switch the codes, and not standby the transponder. And I suggest caution when dialing through "7xxx" although controllers I have talked to say it's not a big deal.



          So the idea is to keep the transponder squawking, even though numbers are being changed. There is continuity in that they will continue to have returns while you are playing with the knobs. And if you ever have a switch failure, it will likely be on the ground.



          Addendum: Also, with ADS-B, one is supposed to keep the transponder on at all times, when on the airport surface in a movement area. So I can see that the philosophy of managing the standby position will continue to change.






          share|improve this answer























          • Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
            – Lnafziger
            3 hours ago






          • 1




            Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
            – user71659
            3 hours ago










          • For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
            – mongo
            2 hours ago


















          up vote
          4
          down vote













          The AIM implies that you should leave the transponder on ALT when changing codes—since if you are in standby you won’t be transmitting:




          4−1−20. Transponder Operation



          e. Code Changes




          1. When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false
            alarms at automated ground facilities. For example, when switching
            from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to
            7700 and then 7200. This procedure applies to nondiscrete Code 7500
            and all discrete codes in the 7600 and 7700 series (i.e., 7600−7677,
            7700−7777) which will trigger special indicators in automated
            facilities. Only nondiscrete Code 7500 will be decoded as the hijack
            code.







          share|improve this answer





















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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            10
            down vote













            The FAA started advocating not selecting standby for code changes after it was found that more often than one would expect, the transponder doesn't always come back on after standby. Seems they uncovered a number of switch failures.



            I figure that someone decided that for TCAS it was better to have a transponder squawking any code than not squawking. But that is my own conjecture.



            So for quite a few years the guidance has been to not turn to standby when selecting codes.



            I have had the folks at Flight Safety lecture me after sim sessions, with pretty much the same story.



            So I now teach students to just switch the codes, and not standby the transponder. And I suggest caution when dialing through "7xxx" although controllers I have talked to say it's not a big deal.



            So the idea is to keep the transponder squawking, even though numbers are being changed. There is continuity in that they will continue to have returns while you are playing with the knobs. And if you ever have a switch failure, it will likely be on the ground.



            Addendum: Also, with ADS-B, one is supposed to keep the transponder on at all times, when on the airport surface in a movement area. So I can see that the philosophy of managing the standby position will continue to change.






            share|improve this answer























            • Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
              – Lnafziger
              3 hours ago






            • 1




              Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
              – user71659
              3 hours ago










            • For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
              – mongo
              2 hours ago















            up vote
            10
            down vote













            The FAA started advocating not selecting standby for code changes after it was found that more often than one would expect, the transponder doesn't always come back on after standby. Seems they uncovered a number of switch failures.



            I figure that someone decided that for TCAS it was better to have a transponder squawking any code than not squawking. But that is my own conjecture.



            So for quite a few years the guidance has been to not turn to standby when selecting codes.



            I have had the folks at Flight Safety lecture me after sim sessions, with pretty much the same story.



            So I now teach students to just switch the codes, and not standby the transponder. And I suggest caution when dialing through "7xxx" although controllers I have talked to say it's not a big deal.



            So the idea is to keep the transponder squawking, even though numbers are being changed. There is continuity in that they will continue to have returns while you are playing with the knobs. And if you ever have a switch failure, it will likely be on the ground.



            Addendum: Also, with ADS-B, one is supposed to keep the transponder on at all times, when on the airport surface in a movement area. So I can see that the philosophy of managing the standby position will continue to change.






            share|improve this answer























            • Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
              – Lnafziger
              3 hours ago






            • 1




              Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
              – user71659
              3 hours ago










            • For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
              – mongo
              2 hours ago













            up vote
            10
            down vote










            up vote
            10
            down vote









            The FAA started advocating not selecting standby for code changes after it was found that more often than one would expect, the transponder doesn't always come back on after standby. Seems they uncovered a number of switch failures.



            I figure that someone decided that for TCAS it was better to have a transponder squawking any code than not squawking. But that is my own conjecture.



            So for quite a few years the guidance has been to not turn to standby when selecting codes.



            I have had the folks at Flight Safety lecture me after sim sessions, with pretty much the same story.



            So I now teach students to just switch the codes, and not standby the transponder. And I suggest caution when dialing through "7xxx" although controllers I have talked to say it's not a big deal.



            So the idea is to keep the transponder squawking, even though numbers are being changed. There is continuity in that they will continue to have returns while you are playing with the knobs. And if you ever have a switch failure, it will likely be on the ground.



            Addendum: Also, with ADS-B, one is supposed to keep the transponder on at all times, when on the airport surface in a movement area. So I can see that the philosophy of managing the standby position will continue to change.






            share|improve this answer














            The FAA started advocating not selecting standby for code changes after it was found that more often than one would expect, the transponder doesn't always come back on after standby. Seems they uncovered a number of switch failures.



            I figure that someone decided that for TCAS it was better to have a transponder squawking any code than not squawking. But that is my own conjecture.



            So for quite a few years the guidance has been to not turn to standby when selecting codes.



            I have had the folks at Flight Safety lecture me after sim sessions, with pretty much the same story.



            So I now teach students to just switch the codes, and not standby the transponder. And I suggest caution when dialing through "7xxx" although controllers I have talked to say it's not a big deal.



            So the idea is to keep the transponder squawking, even though numbers are being changed. There is continuity in that they will continue to have returns while you are playing with the knobs. And if you ever have a switch failure, it will likely be on the ground.



            Addendum: Also, with ADS-B, one is supposed to keep the transponder on at all times, when on the airport surface in a movement area. So I can see that the philosophy of managing the standby position will continue to change.







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited 2 hours ago

























            answered 5 hours ago









            mongo

            11.3k1052




            11.3k1052












            • Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
              – Lnafziger
              3 hours ago






            • 1




              Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
              – user71659
              3 hours ago










            • For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
              – mongo
              2 hours ago


















            • Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
              – Lnafziger
              3 hours ago






            • 1




              Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
              – user71659
              3 hours ago










            • For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
              – mongo
              2 hours ago
















            Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
            – Lnafziger
            3 hours ago




            Also, it is probably more likely for it to be "pilot error" than "switch failure" when the transponder doesn't come back on after setting the code....
            – Lnafziger
            3 hours ago




            1




            1




            Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
            – user71659
            3 hours ago




            Modern electronically controlled transponders have a delay that waits until a few seconds after dialing stops before committing the change. And a lot of them are keypad entry now, which avoids the problem too.
            – user71659
            3 hours ago












            For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
            – mongo
            2 hours ago




            For a while I would fly a plane daily which would not do the 0400 bit, and of course the local TRACON assigned 0400 bit codes. The unit would go to the shop, get certified and then the switch(i assume) would get spotty. I would negotiate another code with ATC. The only people who were really annoyed were the NYC TRACON folks. Then again, at one time, I flew equipment which had two digit transponders. Yep, 12 for VFR.
            – mongo
            2 hours ago










            up vote
            4
            down vote













            The AIM implies that you should leave the transponder on ALT when changing codes—since if you are in standby you won’t be transmitting:




            4−1−20. Transponder Operation



            e. Code Changes




            1. When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false
              alarms at automated ground facilities. For example, when switching
              from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to
              7700 and then 7200. This procedure applies to nondiscrete Code 7500
              and all discrete codes in the 7600 and 7700 series (i.e., 7600−7677,
              7700−7777) which will trigger special indicators in automated
              facilities. Only nondiscrete Code 7500 will be decoded as the hijack
              code.







            share|improve this answer

























              up vote
              4
              down vote













              The AIM implies that you should leave the transponder on ALT when changing codes—since if you are in standby you won’t be transmitting:




              4−1−20. Transponder Operation



              e. Code Changes




              1. When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false
                alarms at automated ground facilities. For example, when switching
                from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to
                7700 and then 7200. This procedure applies to nondiscrete Code 7500
                and all discrete codes in the 7600 and 7700 series (i.e., 7600−7677,
                7700−7777) which will trigger special indicators in automated
                facilities. Only nondiscrete Code 7500 will be decoded as the hijack
                code.







              share|improve this answer























                up vote
                4
                down vote










                up vote
                4
                down vote









                The AIM implies that you should leave the transponder on ALT when changing codes—since if you are in standby you won’t be transmitting:




                4−1−20. Transponder Operation



                e. Code Changes




                1. When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false
                  alarms at automated ground facilities. For example, when switching
                  from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to
                  7700 and then 7200. This procedure applies to nondiscrete Code 7500
                  and all discrete codes in the 7600 and 7700 series (i.e., 7600−7677,
                  7700−7777) which will trigger special indicators in automated
                  facilities. Only nondiscrete Code 7500 will be decoded as the hijack
                  code.







                share|improve this answer












                The AIM implies that you should leave the transponder on ALT when changing codes—since if you are in standby you won’t be transmitting:




                4−1−20. Transponder Operation



                e. Code Changes




                1. When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false
                  alarms at automated ground facilities. For example, when switching
                  from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to
                  7700 and then 7200. This procedure applies to nondiscrete Code 7500
                  and all discrete codes in the 7600 and 7700 series (i.e., 7600−7677,
                  7700−7777) which will trigger special indicators in automated
                  facilities. Only nondiscrete Code 7500 will be decoded as the hijack
                  code.








                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 4 hours ago









                JScarry

                3,7641623




                3,7641623






















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