Narrative:

Our aircraft was given a descent from FL390 down to FL350. We were approximately 160 NM from our destination of tri, so we began a slow descent approximately 1000 FPM. At FL380 ZDC asked our altitude and we stated FL380 descending to FL350. Immediately, ATC said 'mdt X, you were supposed to be at FL390, turn now right to heading 330 degrees.' so immediately we climbed rapidly back to FL390 and began turn to heading 330 degrees. Then ATC gave aircraft Y a turn to change heading. As we were climbing through FL385, another aircraft popped up on our TCASII screen that was not there at our lower altitude. He appeared to be at our 11 O'clock position and approximately 10 mi away level at FL370. When our heading was going through 300 degrees and altitude FL390, ATC gave us a turn back direct psk VOR heading 259 degrees. I told ATC we heard him call mdt X and I repeated mdt X descend to FL350, and he said the descent was for aircraft Y. We then asked if there would be a report filed and ATC said no, that there was not a problem. I feel very strongly that ATC just gave us (mdt X) the descent and didn't realize it until he saw the conflict on his radar screen. I do know for a fact that I did repeat mdt X cleared down to FL350 and ATC didn't respond. So part of the problem was he didn't listen carefully to the readback, if he cleared aircraft Y instead of mdt X. Also, from talking to him, I think he realized he made the mistake. I also think our TCASII had a blind spot and that is why we didn't see the other aircraft until we had climbed 500 ft. Incidentally, there was no TCASII advisories and I don't think we were close enough to have gotten one either.

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Original NASA ASRS Text

Title: FLC OF A CPR MLG RESPONDED TO ANOTHER ACFT'S CLRNC AND DID NOT KNOW THAT UNTIL ARTCC RADAR CTLR INTERVENED DURING THEIR DSCNT. THEY IMMEDIATELY RETURNED TO ASSIGNED AND THE CTLR ASSIGNED VECTORS TO AVOID CONFLICTING TFC.

Narrative: OUR ACFT WAS GIVEN A DSCNT FROM FL390 DOWN TO FL350. WE WERE APPROX 160 NM FROM OUR DEST OF TRI, SO WE BEGAN A SLOW DSCNT APPROX 1000 FPM. AT FL380 ZDC ASKED OUR ALT AND WE STATED FL380 DSNDING TO FL350. IMMEDIATELY, ATC SAID 'MDT X, YOU WERE SUPPOSED TO BE AT FL390, TURN NOW R TO HDG 330 DEGS.' SO IMMEDIATELY WE CLBED RAPIDLY BACK TO FL390 AND BEGAN TURN TO HDG 330 DEGS. THEN ATC GAVE ACFT Y A TURN TO CHANGE HDG. AS WE WERE CLBING THROUGH FL385, ANOTHER ACFT POPPED UP ON OUR TCASII SCREEN THAT WAS NOT THERE AT OUR LOWER ALT. HE APPEARED TO BE AT OUR 11 O'CLOCK POS AND APPROX 10 MI AWAY LEVEL AT FL370. WHEN OUR HDG WAS GOING THROUGH 300 DEGS AND ALT FL390, ATC GAVE US A TURN BACK DIRECT PSK VOR HDG 259 DEGS. I TOLD ATC WE HEARD HIM CALL MDT X AND I REPEATED MDT X DSND TO FL350, AND HE SAID THE DSCNT WAS FOR ACFT Y. WE THEN ASKED IF THERE WOULD BE A RPT FILED AND ATC SAID NO, THAT THERE WAS NOT A PROB. I FEEL VERY STRONGLY THAT ATC JUST GAVE US (MDT X) THE DSCNT AND DIDN'T REALIZE IT UNTIL HE SAW THE CONFLICT ON HIS RADAR SCREEN. I DO KNOW FOR A FACT THAT I DID REPEAT MDT X CLRED DOWN TO FL350 AND ATC DIDN'T RESPOND. SO PART OF THE PROB WAS HE DIDN'T LISTEN CAREFULLY TO THE READBACK, IF HE CLRED ACFT Y INSTEAD OF MDT X. ALSO, FROM TALKING TO HIM, I THINK HE REALIZED HE MADE THE MISTAKE. I ALSO THINK OUR TCASII HAD A BLIND SPOT AND THAT IS WHY WE DIDN'T SEE THE OTHER ACFT UNTIL WE HAD CLBED 500 FT. INCIDENTALLY, THERE WAS NO TCASII ADVISORIES AND I DON'T THINK WE WERE CLOSE ENOUGH TO HAVE GOTTEN ONE EITHER.

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.