Narrative:

We were aircraft X, lga-dca. Inbound to dca VOR, 115 degree radial, 22 DME, level at 10000 ft MSL, 25O KTS, heading 295 degrees, dc approach 124.2 MHZ. During the approximately 15 seconds this event encompassed, we were in VMC in daylight between clouds including cumulo nimbus. I found out later that the other aircraft was aircraft Y inbound to bwi working balance approach. Our initial indication of the other aircraft was a TCASII TA followed immediately by an RA telling us to descend. On my TCASII indicator the subject aircraft was directly in front of us, 700 ft above us descending towards us, inside the 2.5 mi ring on the indicator. Then several things happened almost at once. I started a descent, looked up and saw the aircraft, looked down at the TCASII indicator and saw he was 300 ft above us still descending, less than 1 mi in front of us, started a left turn, looked up and saw him in what appeared to be a pull-up and turn to his left as he passed to our right side. I would estimate when he went by us he was no more than 100 ft above us and about 500-1000 ft horizontal away. We reported the near miss to ATC and proceeded to a normal arrival. Shortly after arrival, I talked to a supervisor at the dca TRACON. He said they were investigating this event as a 'system error.' he very candidly admitted to me that the aircraft Y flight had been given a descent clearance through our altitude due to miscom between the dca and balance tracons.

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Original NASA ASRS Text

Title: B727 FLC INBOUND TO DCA RECEIVED A TCASII RA REQUIRING IMMEDIATE EVASIVE ACTION. ATC ADMITTED A B767 HAD BEEN GIVEN A DSCNT CLRNC THROUGH THE B727'S ALT.

Narrative: WE WERE ACFT X, LGA-DCA. INBOUND TO DCA VOR, 115 DEG RADIAL, 22 DME, LEVEL AT 10000 FT MSL, 25O KTS, HDG 295 DEGS, DC APCH 124.2 MHZ. DURING THE APPROX 15 SECONDS THIS EVENT ENCOMPASSED, WE WERE IN VMC IN DAYLIGHT BTWN CLOUDS INCLUDING CUMULO NIMBUS. I FOUND OUT LATER THAT THE OTHER ACFT WAS ACFT Y INBOUND TO BWI WORKING BAL APCH. OUR INITIAL INDICATION OF THE OTHER ACFT WAS A TCASII TA FOLLOWED IMMEDIATELY BY AN RA TELLING US TO DSND. ON MY TCASII INDICATOR THE SUBJECT ACFT WAS DIRECTLY IN FRONT OF US, 700 FT ABOVE US DSNDING TOWARDS US, INSIDE THE 2.5 MI RING ON THE INDICATOR. THEN SEVERAL THINGS HAPPENED ALMOST AT ONCE. I STARTED A DSCNT, LOOKED UP AND SAW THE ACFT, LOOKED DOWN AT THE TCASII INDICATOR AND SAW HE WAS 300 FT ABOVE US STILL DSNDING, LESS THAN 1 MI IN FRONT OF US, STARTED A L TURN, LOOKED UP AND SAW HIM IN WHAT APPEARED TO BE A PULL-UP AND TURN TO HIS L AS HE PASSED TO OUR R SIDE. I WOULD ESTIMATE WHEN HE WENT BY US HE WAS NO MORE THAN 100 FT ABOVE US AND ABOUT 500-1000 FT HORIZ AWAY. WE RPTED THE NEAR MISS TO ATC AND PROCEEDED TO A NORMAL ARR. SHORTLY AFTER ARR, I TALKED TO A SUPVR AT THE DCA TRACON. HE SAID THEY WERE INVESTIGATING THIS EVENT AS A 'SYS ERROR.' HE VERY CANDIDLY ADMITTED TO ME THAT THE ACFT Y FLT HAD BEEN GIVEN A DSCNT CLRNC THROUGH OUR ALT DUE TO MISCOM BTWN THE DCA AND BAL TRACONS.

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.