Narrative:

The flight was descending into the baltimore area via the ott-1 arrival to bwi. Wash center handed us off to approach, and upon changing frequency we heard the controller handling numerous flts in rapid succession. The controller was extremely busy and his transmissions were so close together that we could not break in for our initial contact call. We continued to ott and then outbnd on the arrival at 14000' assigned toward jetta, awaiting a break or a call from approach. The controller was obviously handling a tremendous traffic load and was speaking very fast to keep up with the flow. Finally, as we were approaching jetta with no further instructions and no call from approach, the captain began attempts to break in. After about three attempts with no response and as we were crossing jetta, it finally became obvious the situation was not normal. We crossed jetta with no instructions and proceeded directly to bwi on the published arrival. The captain broke in again and advised that we were proceeding from jetta direct to bwi and requested further instructions. Finally the controller acknowledged the captain's call, but questioned who we were and where we were going. He was extremely busy and was trying to help, but his voice was tense from the workload and he did not recognize our callsign, or know what to do with us. The captain advised that our destination was bwi and he responded that he was wash nat'l approach and gave the captain a frequency for bwi approach. By now I had begun to call on the published frequency on the approach plate, and directed the captain to the #2 radio upon which I had contacted bwi approach. Bwi approach advised the captain he had no contact and directed us to a new transponder code. I complied and also switched to the #2 transponder. Bwi approach picked us up immediately and vectored us for a visibility approach. Subsequent phone conversations revealed the transponder failed as we descended thru FL190 and we had been uncontrolled from that point. The transponder problem was reported to us for the first time two flts later on a return flight inbound to bwi from the north on the same day. The controller advised 'intermittent to inoperative' and maintenance found the #1 transponder to be faulty and replaced it. Although the situation was the result of equipment failure, the main problem appears to be the result of an extremely burdened human workload. The controller sounded very professional, capable, and competent. The loss of beacon code compounded by such high density traffic, and simultaneous with the change of controling agencies, appears to be too much to expect of human capabilities on a daily basis. The rapid fire communication, also caused the flight crew to delay recognition of the problem as it could not be determined if the controller was delaying response to our calls due to workload or because of the abnormal situation.

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Original NASA ASRS Text

Title: NON DETECTION OF ACFT BY TRACON RADAR AFTER HANDOFF FROM ARTCC. TRANSPONDER FAILURE AT TIME OF HANDOFF CONTRIBUTED TO THE PROBLEM.

Narrative: THE FLT WAS DSNDING INTO THE BALTIMORE AREA VIA THE OTT-1 ARR TO BWI. WASH CTR HANDED US OFF TO APCH, AND UPON CHANGING FREQ WE HEARD THE CTLR HANDLING NUMEROUS FLTS IN RAPID SUCCESSION. THE CTLR WAS EXTREMELY BUSY AND HIS TRANSMISSIONS WERE SO CLOSE TOGETHER THAT WE COULD NOT BREAK IN FOR OUR INITIAL CONTACT CALL. WE CONTINUED TO OTT AND THEN OUTBND ON THE ARR AT 14000' ASSIGNED TOWARD JETTA, AWAITING A BREAK OR A CALL FROM APCH. THE CTLR WAS OBVIOUSLY HANDLING A TREMENDOUS TFC LOAD AND WAS SPEAKING VERY FAST TO KEEP UP WITH THE FLOW. FINALLY, AS WE WERE APCHING JETTA WITH NO FURTHER INSTRUCTIONS AND NO CALL FROM APCH, THE CAPT BEGAN ATTEMPTS TO BREAK IN. AFTER ABOUT THREE ATTEMPTS WITH NO RESPONSE AND AS WE WERE XING JETTA, IT FINALLY BECAME OBVIOUS THE SITUATION WAS NOT NORMAL. WE CROSSED JETTA WITH NO INSTRUCTIONS AND PROCEEDED DIRECTLY TO BWI ON THE PUBLISHED ARR. THE CAPT BROKE IN AGAIN AND ADVISED THAT WE WERE PROCEEDING FROM JETTA DIRECT TO BWI AND REQUESTED FURTHER INSTRUCTIONS. FINALLY THE CTLR ACKNOWLEDGED THE CAPT'S CALL, BUT QUESTIONED WHO WE WERE AND WHERE WE WERE GOING. HE WAS EXTREMELY BUSY AND WAS TRYING TO HELP, BUT HIS VOICE WAS TENSE FROM THE WORKLOAD AND HE DID NOT RECOGNIZE OUR CALLSIGN, OR KNOW WHAT TO DO WITH US. THE CAPT ADVISED THAT OUR DEST WAS BWI AND HE RESPONDED THAT HE WAS WASH NAT'L APCH AND GAVE THE CAPT A FREQ FOR BWI APCH. BY NOW I HAD BEGUN TO CALL ON THE PUBLISHED FREQ ON THE APCH PLATE, AND DIRECTED THE CAPT TO THE #2 RADIO UPON WHICH I HAD CONTACTED BWI APCH. BWI APCH ADVISED THE CAPT HE HAD NO CONTACT AND DIRECTED US TO A NEW TRANSPONDER CODE. I COMPLIED AND ALSO SWITCHED TO THE #2 TRANSPONDER. BWI APCH PICKED US UP IMMEDIATELY AND VECTORED US FOR A VIS APCH. SUBSEQUENT PHONE CONVERSATIONS REVEALED THE TRANSPONDER FAILED AS WE DSNDED THRU FL190 AND WE HAD BEEN UNCONTROLLED FROM THAT POINT. THE TRANSPONDER PROB WAS RPTED TO US FOR THE FIRST TIME TWO FLTS LATER ON A RETURN FLT INBND TO BWI FROM THE N ON THE SAME DAY. THE CTLR ADVISED 'INTERMITTENT TO INOP' AND MAINT FOUND THE #1 TRANSPONDER TO BE FAULTY AND REPLACED IT. ALTHOUGH THE SITUATION WAS THE RESULT OF EQUIP FAILURE, THE MAIN PROB APPEARS TO BE THE RESULT OF AN EXTREMELY BURDENED HUMAN WORKLOAD. THE CTLR SOUNDED VERY PROFESSIONAL, CAPABLE, AND COMPETENT. THE LOSS OF BEACON CODE COMPOUNDED BY SUCH HIGH DENSITY TFC, AND SIMULTANEOUS WITH THE CHANGE OF CTLING AGENCIES, APPEARS TO BE TOO MUCH TO EXPECT OF HUMAN CAPABILITIES ON A DAILY BASIS. THE RAPID FIRE COM, ALSO CAUSED THE FLT CREW TO DELAY RECOGNITION OF THE PROB AS IT COULD NOT BE DETERMINED IF THE CTLR WAS DELAYING RESPONSE TO OUR CALLS DUE TO WORKLOAD OR BECAUSE OF THE ABNORMAL SITUATION.

Data retrieved from NASA's ASRS site as of August 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.