Narrative:

I was returning to jyo from ozw on an IFR flight plan, squawking in VMC conditions. Approximately 8 NM west of jyo, I asked approach control to cancel IFR as I had the field in sight. I was informed to stay with ATC as there were several targets in opposite direction of flight, but I could switch to unicom. I entered cross wind at midfield at pattern altitude, monitoring both approach and unicom. Downwind prior to turning base, I contacted ATC announcing my position and canceling IFR. The controller acknowledged and thanked me. I did not hear any instructions to continue squawking. I punched VFR into transponder, a reflex action when canceling IFR at an uncontrolled field. I would positively recommend that controllers emphasize not to change transponder code within the washington area. My feelings are that many pilots have developed the same habit when canceling IFR at a uncontrolled field. I was surprised upon landing when I was requested to call a phone number. I called and was informed that I landed at jyo without an assigned discrete code.

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Original NASA ASRS Text

Title: BE36 PLT ADVISED AFTER LNDG JYO THAT HE CHANGED HIS TRANSPONDER CODE TO 1200 PRIOR TO LNDG IN VIOLATION TO DC ADIZ RESTRS.

Narrative: I WAS RETURNING TO JYO FROM OZW ON AN IFR FLT PLAN, SQUAWKING IN VMC CONDITIONS. APPROX 8 NM W OF JYO, I ASKED APCH CTL TO CANCEL IFR AS I HAD THE FIELD IN SIGHT. I WAS INFORMED TO STAY WITH ATC AS THERE WERE SEVERAL TARGETS IN OPPOSITE DIRECTION OF FLT, BUT I COULD SWITCH TO UNICOM. I ENTERED CROSS WIND AT MIDFIELD AT PATTERN ALT, MONITORING BOTH APCH AND UNICOM. DOWNWIND PRIOR TO TURNING BASE, I CONTACTED ATC ANNOUNCING MY POSITION AND CANCELING IFR. THE CTLR ACKNOWLEDGED AND THANKED ME. I DID NOT HEAR ANY INSTRUCTIONS TO CONTINUE SQUAWKING. I PUNCHED VFR INTO TRANSPONDER, A REFLEX ACTION WHEN CANCELING IFR AT AN UNCTLED FIELD. I WOULD POSITIVELY RECOMMEND THAT CTLRS EMPHASIZE NOT TO CHANGE TRANSPONDER CODE WITHIN THE WASHINGTON AREA. MY FEELINGS ARE THAT MANY PLTS HAVE DEVELOPED THE SAME HABIT WHEN CANCELING IFR AT A UNCTLED FIELD. I WAS SURPRISED UPON LNDG WHEN I WAS REQUESTED TO CALL A PHONE NUMBER. I CALLED AND WAS INFORMED THAT I LANDED AT JYO WITHOUT AN ASSIGNED DISCRETE CODE.

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.