Narrative:

I violated the washington baltimore ADIZ by resetting my squawk code from the assigned code I received prior to entering the ADIZ to 1200 during my approach to leesburg, va, airport for landing. I reset the code after receiving ATC communications terminating radar service and approving frequency change to the leesburg CTAF. Upon landing, I was informed of the infraction by potomac TRACON there is no question but that I reset the code. At the same time, I am very aware of the ADIZ procedure to maintain the assigned code within the ADIZ until landing. I have replayed the events numerous times and cannot come up with a reason other than simply making a habitual procedure associated with the termination of radar service. I have requested a copy of the ATC recordings between the controller and myself to see if there was anything in the communications that prompted me to reset the transponder when I did. Usual ATC communications in the ADIZ include instructions to maintain the code until on the ground. However, I cannot recall whether that phrase was or was not included in this instance.

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Original NASA ASRS Text

Title: PLT OF C182 OPERATING IN DC ADIZ INADVERTENTLY SWITCHED TO 1200 SQUAWK WHEN TERMINATED FROM RADAR SVC WHILE LNDG AT JYO.

Narrative: I VIOLATED THE WASHINGTON BALTIMORE ADIZ BY RESETTING MY SQUAWK CODE FROM THE ASSIGNED CODE I RECEIVED PRIOR TO ENTERING THE ADIZ TO 1200 DURING MY APCH TO LEESBURG, VA, ARPT FOR LNDG. I RESET THE CODE AFTER RECEIVING ATC COMS TERMINATING RADAR SVC AND APPROVING FREQ CHANGE TO THE LEESBURG CTAF. UPON LNDG, I WAS INFORMED OF THE INFRACTION BY POTOMAC TRACON THERE IS NO QUESTION BUT THAT I RESET THE CODE. AT THE SAME TIME, I AM VERY AWARE OF THE ADIZ PROC TO MAINTAIN THE ASSIGNED CODE WITHIN THE ADIZ UNTIL LNDG. I HAVE REPLAYED THE EVENTS NUMEROUS TIMES AND CANNOT COME UP WITH A REASON OTHER THAN SIMPLY MAKING A HABITUAL PROC ASSOCIATED WITH THE TERMINATION OF RADAR SVC. I HAVE REQUESTED A COPY OF THE ATC RECORDINGS BTWN THE CTLR AND MYSELF TO SEE IF THERE WAS ANYTHING IN THE COMS THAT PROMPTED ME TO RESET THE XPONDER WHEN I DID. USUAL ATC COMS IN THE ADIZ INCLUDE INSTRUCTIONS TO MAINTAIN THE CODE UNTIL ON THE GND. HOWEVER, I CANNOT RECALL WHETHER THAT PHRASE WAS OR WAS NOT INCLUDED IN THIS INSTANCE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.