Narrative:

The aircraft involved were: 1) X T/SF34/a dca-bos J121 nebound. 2) Y T/B73F/right fll-isp J121 nebound. 3) Z T/DH8/a isp-bwi J121 swbound. Z was handed off to zcw sector 59. Due to the early automated handoff, the full data block dropped off, and I monitored the flight's limited data block. X at FL190 and Y descending to FL210 were accepted from W59. Shortly after X and Y checked on my frequency, I issued traffic on the Z to both aircraft. Y was level at FL210 or just leveling off just prior to the incident. Y advised me that he had an RA. I asked if he was climbing or descending. On the second request Y said he was climbing. As Y was responding, I noticed the limited data on Z start descending. I remember seeing FL196 in the limited data block. At the time of Z's descent, he was about 3 mi head- on with X at FL190. I turned X to the east to avoid what I perceived was a possible midair collision. Y reported back at FL210. I do not recall seeing anything other than '210C' in his data block. When X was clear of Z, I turned him back to course. My handoff man called W59 as I was turning X. He told me they said Z had a TCASII RA. Several mins later, I asked X if he had an RA. He said they had a TA but not an RA. He also said that they saw the target coming at them on TCASII and were already turning when I issued the turn.

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Original NASA ASRS Text

Title: ACR Z TCASII UNAUTH DSCNT FROM ASSIGNED ALT NON ADHERENCE TO ATC CLRNC HAD LTSS FROM ACR X. EVASIVE ACTION TAKEN.

Narrative: THE ACFT INVOLVED WERE: 1) X T/SF34/A DCA-BOS J121 NEBOUND. 2) Y T/B73F/R FLL-ISP J121 NEBOUND. 3) Z T/DH8/A ISP-BWI J121 SWBOUND. Z WAS HANDED OFF TO ZCW SECTOR 59. DUE TO THE EARLY AUTOMATED HDOF, THE FULL DATA BLOCK DROPPED OFF, AND I MONITORED THE FLT'S LIMITED DATA BLOCK. X AT FL190 AND Y DSNDING TO FL210 WERE ACCEPTED FROM W59. SHORTLY AFTER X AND Y CHKED ON MY FREQ, I ISSUED TFC ON THE Z TO BOTH ACFT. Y WAS LEVEL AT FL210 OR JUST LEVELING OFF JUST PRIOR TO THE INCIDENT. Y ADVISED ME THAT HE HAD AN RA. I ASKED IF HE WAS CLBING OR DSNDING. ON THE SECOND REQUEST Y SAID HE WAS CLBING. AS Y WAS RESPONDING, I NOTICED THE LIMITED DATA ON Z START DSNDING. I REMEMBER SEEING FL196 IN THE LIMITED DATA BLOCK. AT THE TIME OF Z'S DSCNT, HE WAS ABOUT 3 MI HEAD- ON WITH X AT FL190. I TURNED X TO THE E TO AVOID WHAT I PERCEIVED WAS A POSSIBLE MIDAIR COLLISION. Y RPTED BACK AT FL210. I DO NOT RECALL SEEING ANYTHING OTHER THAN '210C' IN HIS DATA BLOCK. WHEN X WAS CLR OF Z, I TURNED HIM BACK TO COURSE. MY HDOF MAN CALLED W59 AS I WAS TURNING X. HE TOLD ME THEY SAID Z HAD A TCASII RA. SEVERAL MINS LATER, I ASKED X IF HE HAD AN RA. HE SAID THEY HAD A TA BUT NOT AN RA. HE ALSO SAID THAT THEY SAW THE TARGET COMING AT THEM ON TCASII AND WERE ALREADY TURNING WHEN I ISSUED THE TURN.

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.