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!