Narrative:

Air carrier X, a turbojet departure from dca to stl checked in climbing out of 12000 ft for 17000 ft. I was conducting OJT at the time on north and south high radar combined. Air carrier X then reported an aircraft that flew approximately 300 ft under the nose and asked if we were working it. We (the developmental and myself) did not observe any target in the vicinity. Air carrier X gave a very specific description of the aircraft, light blue small transport Y or mlt that looked like an FAA small transport. I then observed a primary only target about 3-5 mi southeast of air carrier X heading sbound. I then initiated a primary computer track 1 and we followed the aircraft to daa (davison aaf). The pilot later called on the phone and said he was at 13500 ft traveling from hgr to daa and knew he had a transponder problem. I suspect he was trying to avoid class B airspace but forgot about mode C veil and transponder requirements above 12500 ft. He said he saw air carrier X climbing and started a descent to get underneath. While we were talking to the air carrier X pilot, getting details, another air carrier, air carrier Z, 10 east of mrb cleared to 11000 ft had a TCASII RA on a VFR aircraft at 11500 ft that we didn't call because of near midair collision. Supplemental information from acn 258259: while working iad departure on climb out of dca en route to stl, at XX15 EST, a near miss event occurred. I was the first officer on the flight and the PF this particular leg. At approximately 30 NM east of ldn VOR on the approximately 90 degree radial, I observed a t-tail small transport Y, bluish in color, with what I can best recollect, a military 'STAR insignia' on the fuselage. I first made contact, visually, with the target at my 1 O'clock position, flying at or near our present altitude. The small transport was flying a north to south course and our paths crossed at near 90 degrees perpendicular with the event aircraft passing within 200 ft below and in front of our aircraft. No abrupt evasive maneuvers were taken as the event was over in just a second or two. The WX in-flight was VMC and unlimited ceiling and visibility. The sun was at our 12 O'clock, setting, and I had my attention focused outside before the traffic was spotted. The captain was alerted to the traffic by my callout and he too acquired the traffic as it passed under our nose. The captain estimated the vertical distance as it passed the left side of the aircraft at 200-300 ft below our altitude on the climb. The captain (PNF) immediately queried the controller and the controller replied that he did not have any traffic in our vicinity. His next transmission, approximately 1 min later, he indicated that he now had a 'primary target' with no altitude information. Shortly after this transmission we overheard an air carrier Z flight in our proximity. After being issued an altitude change, received a TCASII RA not to, I believe, descend. The captain and I both believe that it was the same traffic we almost hit. I recollect the air carrier Z crew member saying 'it's a light twin, in sight' to the controller. Our TCASII equipment was on and the TA/RA mode selected. We were operating in the above 'seek position' at the 20 NM range. Our altitude at the time of the near 'tragedy' was 12000-13000 ft MSL. Either our TCASII equipment malfunctioned, which we don't have any reason to assume (it was working fine before and after), or the subject aircraft was flying in class 'east' airspace with the transponder selected 'off.' both the captain and I feel that the latter was the case and when we scared the sxxx out of him/her the transponder was checked, found 'off' then selected 'on.' this explains the air carrier Z 'RA!' of course there is a lot of assumptions being made, but they fit the scenario to a tee. If all the technologies and pilot awareness are in place, as they were this day, it takes just 1 small switch 'out of place' to cause a tragedy of immense proportions. 1 small fraction of a second either way could have filled the media with senseless 'sensationalism' for months. Human error will always be in the loop, so we must always strive to be more diligent in our flying!

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Original NASA ASRS Text

Title: ACR HAS AN NMAC CLBING OUT ABOVE TCA WITH VFR ACFT. VFR ACFT HAD INTERMITTENT XPONDER PROB.

Narrative: ACR X, A TURBOJET DEP FROM DCA TO STL CHKED IN CLBING OUT OF 12000 FT FOR 17000 FT. I WAS CONDUCTING OJT AT THE TIME ON N AND S HIGH RADAR COMBINED. ACR X THEN RPTED AN ACFT THAT FLEW APPROX 300 FT UNDER THE NOSE AND ASKED IF WE WERE WORKING IT. WE (THE DEVELOPMENTAL AND MYSELF) DID NOT OBSERVE ANY TARGET IN THE VICINITY. ACR X GAVE A VERY SPECIFIC DESCRIPTION OF THE ACFT, LIGHT BLUE SMT Y OR MLT THAT LOOKED LIKE AN FAA SMT. I THEN OBSERVED A PRIMARY ONLY TARGET ABOUT 3-5 MI SE OF ACR X HDG SBOUND. I THEN INITIATED A PRIMARY COMPUTER TRACK 1 AND WE FOLLOWED THE ACFT TO DAA (DAVISON AAF). THE PLT LATER CALLED ON THE PHONE AND SAID HE WAS AT 13500 FT TRAVELING FROM HGR TO DAA AND KNEW HE HAD A XPONDER PROB. I SUSPECT HE WAS TRYING TO AVOID CLASS B AIRSPACE BUT FORGOT ABOUT MODE C VEIL AND XPONDER REQUIREMENTS ABOVE 12500 FT. HE SAID HE SAW ACR X CLBING AND STARTED A DSCNT TO GET UNDERNEATH. WHILE WE WERE TALKING TO THE ACR X PLT, GETTING DETAILS, ANOTHER ACR, ACR Z, 10 E OF MRB CLRED TO 11000 FT HAD A TCASII RA ON A VFR ACFT AT 11500 FT THAT WE DIDN'T CALL BECAUSE OF NMAC. SUPPLEMENTAL INFORMATION FROM ACN 258259: WHILE WORKING IAD DEP ON CLBOUT OF DCA ENRTE TO STL, AT XX15 EST, A NEAR MISS EVENT OCCURRED. I WAS THE FO ON THE FLT AND THE PF THIS PARTICULAR LEG. AT APPROX 30 NM E OF LDN VOR ON THE APPROX 90 DEG RADIAL, I OBSERVED A T-TAIL SMT Y, BLUISH IN COLOR, WITH WHAT I CAN BEST RECOLLECT, A MIL 'STAR INSIGNIA' ON THE FUSELAGE. I FIRST MADE CONTACT, VISUALLY, WITH THE TARGET AT MY 1 O'CLOCK POS, FLYING AT OR NEAR OUR PRESENT ALT. THE SMT WAS FLYING A N TO S COURSE AND OUR PATHS CROSSED AT NEAR 90 DEGS PERPENDICULAR WITH THE EVENT ACFT PASSING WITHIN 200 FT BELOW AND IN FRONT OF OUR ACFT. NO ABRUPT EVASIVE MANEUVERS WERE TAKEN AS THE EVENT WAS OVER IN JUST A SECOND OR TWO. THE WX INFLT WAS VMC AND UNLIMITED CEILING AND VISIBILITY. THE SUN WAS AT OUR 12 O'CLOCK, SETTING, AND I HAD MY ATTN FOCUSED OUTSIDE BEFORE THE TFC WAS SPOTTED. THE CAPT WAS ALERTED TO THE TFC BY MY CALLOUT AND HE TOO ACQUIRED THE TFC AS IT PASSED UNDER OUR NOSE. THE CAPT ESTIMATED THE VERT DISTANCE AS IT PASSED THE L SIDE OF THE ACFT AT 200-300 FT BELOW OUR ALT ON THE CLB. THE CAPT (PNF) IMMEDIATELY QUERIED THE CTLR AND THE CTLR REPLIED THAT HE DID NOT HAVE ANY TFC IN OUR VICINITY. HIS NEXT XMISSION, APPROX 1 MIN LATER, HE INDICATED THAT HE NOW HAD A 'PRIMARY TARGET' WITH NO ALT INFO. SHORTLY AFTER THIS XMISSION WE OVERHEARD AN ACR Z FLT IN OUR PROX. AFTER BEING ISSUED AN ALT CHANGE, RECEIVED A TCASII RA NOT TO, I BELIEVE, DSND. THE CAPT AND I BOTH BELIEVE THAT IT WAS THE SAME TFC WE ALMOST HIT. I RECOLLECT THE ACR Z CREW MEMBER SAYING 'IT'S A LIGHT TWIN, IN SIGHT' TO THE CTLR. OUR TCASII EQUIP WAS ON AND THE TA/RA MODE SELECTED. WE WERE OPERATING IN THE ABOVE 'SEEK POS' AT THE 20 NM RANGE. OUR ALT AT THE TIME OF THE NEAR 'TRAGEDY' WAS 12000-13000 FT MSL. EITHER OUR TCASII EQUIP MALFUNCTIONED, WHICH WE DON'T HAVE ANY REASON TO ASSUME (IT WAS WORKING FINE BEFORE AND AFTER), OR THE SUBJECT ACFT WAS FLYING IN CLASS 'E' AIRSPACE WITH THE XPONDER SELECTED 'OFF.' BOTH THE CAPT AND I FEEL THAT THE LATTER WAS THE CASE AND WHEN WE SCARED THE SXXX OUT OF HIM/HER THE XPONDER WAS CHKED, FOUND 'OFF' THEN SELECTED 'ON.' THIS EXPLAINS THE ACR Z 'RA!' OF COURSE THERE IS A LOT OF ASSUMPTIONS BEING MADE, BUT THEY FIT THE SCENARIO TO A TEE. IF ALL THE TECHNOLOGIES AND PLT AWARENESS ARE IN PLACE, AS THEY WERE THIS DAY, IT TAKES JUST 1 SMALL SWITCH 'OUT OF PLACE' TO CAUSE A TRAGEDY OF IMMENSE PROPORTIONS. 1 SMALL FRACTION OF A SECOND EITHER WAY COULD HAVE FILLED THE MEDIA WITH SENSELESS 'SENSATIONALISM' FOR MONTHS. HUMAN ERROR WILL ALWAYS BE IN THE LOOP, SO WE MUST ALWAYS STRIVE TO BE MORE DILIGENT IN OUR FLYING!

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.