Narrative:

On feb/sun/04 I departed an airport within the washington metropolitan ADIZ on an instrument training flight, accompanied by a certificated private pilot and instrument student of mine. In compliance with the NOTAM governing the washington ADIZ, we filed an ADIZ flight plan, obtained, entered and squawked a discrete transponder code, and established and maintained 2-WAY communications with ATC. Our initial call to potomac approach was, 'potomac approach, cessna XXX 1400 ft off W00, en route to the deale practice area.' potomac responded, 'cessna XXX potomac approach, roger. Proceed VFR, frequency change approved at pilot's discretion.' approximately 10 mins later, potomac asked, 'is there an XXX on frequency?' I replied that yes, we were on frequency, and had checked in with him about 10 mins prior. He replied that he was not aware of the reason, but that we were to contact TRACON by telephone. After another 20 mins or so of flight training, I heard the controller provide traffic avoidance advisories to 2 aircraft ahead of us, and sounded as if he was describing our aircraft as the traffic. He added in the transmission that he was not 'working' the aircraft in question (us). Shortly thereafter, he said, 'aircraft squawking XXXX (us), potomac.' I replied that it was cessna XXX and that we had already communicated with them a couple of times. After a few mins, he asked us to squawk a new beacon code, which we did. At this point, we decided to return to W00, notified potomac, received a frequency change to CTAF, landed, and called the phone number provided in-flight. The phone number connected me to potomac TRACON, which initially notified me that we were observed by north east air defense sector (neads) after takeoff to be squawking 1200 in the ADIZ, rather than our assigned code of XXXX. I denied this. The next day, I called again to follow up and was informed that we were not, in fact, observed squawking 1200, but that neads did not observe our transponder at all after we finally took off. Because of this, neads tagged us as a threat aircraft and reported us as such, even though we were flying away from washington, dc, and they observed our transponder thereafter. The flight in question was more than my 500TH flight since the washington ADIZ went into effect feb/03. I fly many flts per day in full compliance with the applicable NOTAM, and, therefore, am certainly no stranger to the required procedures and everyday workings of the ADIZ. In fact, I am responsible for teaching ADIZ procedures to my students and other pilots who utilize our airport. Due to the inevitable, occasional radar malfunctions, transponder failures and/or other occurrences, there have been several flts where my transponder was not detected immediately, or at all, by ATC. The difference on those occasions was that I was notified by ATC of the fact, at which point a recycling of the transponder, or a repositioning of the aircraft typically produced radar contact. If it did not, then I was advised to return to the airport and land, which I did. On this occasion, although we had 2-WAY communications, there was no notification by ATC of any radar/transponder problems, without which we would be unaware of any problems. To the contrary, we were told to proceed with our flight upon establishing 2-WAY communications. Furthermore, I was also notified by potomac TRACON by telephone that the reason we were switched mid-flight from a beacon code of XXXX to YYYY was because another aircraft outside of the ADIZ had also been assigned the XXXX code. This, apparently, contributed to the confusion and inability of ATC and/or neads to maintain positive identify of our aircraft during the flight. It is my belief that 3 primary factors contributed to this problem. 1) although we maintained 2-WAY communications with ATC, we were not notified by ATC during our flight of any anomalies. 2) neads detected a radar/transponder problem not relayed to me, nor apparently, to potomac TRACON, which had control over the airspace. 3) our aircraft was assigned a discrete transponder code also assigned to another aircraft. In order to prevent a recurrence of this situation, all federal agencies involved with controling/patrolling the washington ADIZ must communicate moreeffectively and proactively with pilots and with one another. In addition, ATC must take care not to assign specific discrete transponder codes to more than 1 aircraft.

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Original NASA ASRS Text

Title: C172 OPERATING IN THE DC ADIZ IS QUESTIONED REGARDING IDENT.

Narrative: ON FEB/SUN/04 I DEPARTED AN ARPT WITHIN THE WASHINGTON METROPOLITAN ADIZ ON AN INST TRAINING FLT, ACCOMPANIED BY A CERTIFICATED PVT PLT AND INST STUDENT OF MINE. IN COMPLIANCE WITH THE NOTAM GOVERNING THE WASHINGTON ADIZ, WE FILED AN ADIZ FLT PLAN, OBTAINED, ENTERED AND SQUAWKED A DISCRETE XPONDER CODE, AND ESTABLISHED AND MAINTAINED 2-WAY COMS WITH ATC. OUR INITIAL CALL TO POTOMAC APCH WAS, 'POTOMAC APCH, CESSNA XXX 1400 FT OFF W00, ENRTE TO THE DEALE PRACTICE AREA.' POTOMAC RESPONDED, 'CESSNA XXX POTOMAC APCH, ROGER. PROCEED VFR, FREQ CHANGE APPROVED AT PLT'S DISCRETION.' APPROX 10 MINS LATER, POTOMAC ASKED, 'IS THERE AN XXX ON FREQ?' I REPLIED THAT YES, WE WERE ON FREQ, AND HAD CHKED IN WITH HIM ABOUT 10 MINS PRIOR. HE REPLIED THAT HE WAS NOT AWARE OF THE REASON, BUT THAT WE WERE TO CONTACT TRACON BY TELEPHONE. AFTER ANOTHER 20 MINS OR SO OF FLT TRAINING, I HEARD THE CTLR PROVIDE TFC AVOIDANCE ADVISORIES TO 2 ACFT AHEAD OF US, AND SOUNDED AS IF HE WAS DESCRIBING OUR ACFT AS THE TFC. HE ADDED IN THE XMISSION THAT HE WAS NOT 'WORKING' THE ACFT IN QUESTION (US). SHORTLY THEREAFTER, HE SAID, 'ACFT SQUAWKING XXXX (US), POTOMAC.' I REPLIED THAT IT WAS CESSNA XXX AND THAT WE HAD ALREADY COMMUNICATED WITH THEM A COUPLE OF TIMES. AFTER A FEW MINS, HE ASKED US TO SQUAWK A NEW BEACON CODE, WHICH WE DID. AT THIS POINT, WE DECIDED TO RETURN TO W00, NOTIFIED POTOMAC, RECEIVED A FREQ CHANGE TO CTAF, LANDED, AND CALLED THE PHONE NUMBER PROVIDED INFLT. THE PHONE NUMBER CONNECTED ME TO POTOMAC TRACON, WHICH INITIALLY NOTIFIED ME THAT WE WERE OBSERVED BY NORTH EAST AIR DEFENSE SECTOR (NEADS) AFTER TKOF TO BE SQUAWKING 1200 IN THE ADIZ, RATHER THAN OUR ASSIGNED CODE OF XXXX. I DENIED THIS. THE NEXT DAY, I CALLED AGAIN TO FOLLOW UP AND WAS INFORMED THAT WE WERE NOT, IN FACT, OBSERVED SQUAWKING 1200, BUT THAT NEADS DID NOT OBSERVE OUR XPONDER AT ALL AFTER WE FINALLY TOOK OFF. BECAUSE OF THIS, NEADS TAGGED US AS A THREAT ACFT AND RPTED US AS SUCH, EVEN THOUGH WE WERE FLYING AWAY FROM WASHINGTON, DC, AND THEY OBSERVED OUR XPONDER THEREAFTER. THE FLT IN QUESTION WAS MORE THAN MY 500TH FLT SINCE THE WASHINGTON ADIZ WENT INTO EFFECT FEB/03. I FLY MANY FLTS PER DAY IN FULL COMPLIANCE WITH THE APPLICABLE NOTAM, AND, THEREFORE, AM CERTAINLY NO STRANGER TO THE REQUIRED PROCS AND EVERYDAY WORKINGS OF THE ADIZ. IN FACT, I AM RESPONSIBLE FOR TEACHING ADIZ PROCS TO MY STUDENTS AND OTHER PLTS WHO UTILIZE OUR ARPT. DUE TO THE INEVITABLE, OCCASIONAL RADAR MALFUNCTIONS, XPONDER FAILURES AND/OR OTHER OCCURRENCES, THERE HAVE BEEN SEVERAL FLTS WHERE MY XPONDER WAS NOT DETECTED IMMEDIATELY, OR AT ALL, BY ATC. THE DIFFERENCE ON THOSE OCCASIONS WAS THAT I WAS NOTIFIED BY ATC OF THE FACT, AT WHICH POINT A RECYCLING OF THE XPONDER, OR A REPOSITIONING OF THE ACFT TYPICALLY PRODUCED RADAR CONTACT. IF IT DID NOT, THEN I WAS ADVISED TO RETURN TO THE ARPT AND LAND, WHICH I DID. ON THIS OCCASION, ALTHOUGH WE HAD 2-WAY COMS, THERE WAS NO NOTIFICATION BY ATC OF ANY RADAR/XPONDER PROBS, WITHOUT WHICH WE WOULD BE UNAWARE OF ANY PROBS. TO THE CONTRARY, WE WERE TOLD TO PROCEED WITH OUR FLT UPON ESTABLISHING 2-WAY COMS. FURTHERMORE, I WAS ALSO NOTIFIED BY POTOMAC TRACON BY TELEPHONE THAT THE REASON WE WERE SWITCHED MID-FLT FROM A BEACON CODE OF XXXX TO YYYY WAS BECAUSE ANOTHER ACFT OUTSIDE OF THE ADIZ HAD ALSO BEEN ASSIGNED THE XXXX CODE. THIS, APPARENTLY, CONTRIBUTED TO THE CONFUSION AND INABILITY OF ATC AND/OR NEADS TO MAINTAIN POSITIVE IDENT OF OUR ACFT DURING THE FLT. IT IS MY BELIEF THAT 3 PRIMARY FACTORS CONTRIBUTED TO THIS PROB. 1) ALTHOUGH WE MAINTAINED 2-WAY COMS WITH ATC, WE WERE NOT NOTIFIED BY ATC DURING OUR FLT OF ANY ANOMALIES. 2) NEADS DETECTED A RADAR/XPONDER PROB NOT RELAYED TO ME, NOR APPARENTLY, TO POTOMAC TRACON, WHICH HAD CTL OVER THE AIRSPACE. 3) OUR ACFT WAS ASSIGNED A DISCRETE XPONDER CODE ALSO ASSIGNED TO ANOTHER ACFT. IN ORDER TO PREVENT A RECURRENCE OF THIS SIT, ALL FEDERAL AGENCIES INVOLVED WITH CTLING/PATROLLING THE WASHINGTON ADIZ MUST COMMUNICATE MOREEFFECTIVELY AND PROACTIVELY WITH PLTS AND WITH ONE ANOTHER. IN ADDITION, ATC MUST TAKE CARE NOT TO ASSIGN SPECIFIC DISCRETE XPONDER CODES TO MORE THAN 1 ACFT.

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.