Narrative:

I was working the XD45-XB45 shift, 8 hours after working a day shift. ZAB and darc only, and still investigating a fatal crash of an aircraft that just crashed near the sector 21/15 boundary. Coordination was being accomplished with the omic and other agencies regarding the accident. Additionally, there were problems with the 'flushed flight progress strips' and all data was having to be checked/passed manually. Moderate turbulence was a problem at most altitudes from the rockies west. At this time, aircraft X checked in over lvs at FL390 eastbound. Aircraft Y was wbound at FL390. At one point, I ran out the vector lines and observed that the 2 aircraft would pass approximately 12 mi apart. At that time I went back to the previously mentioned tasks. Aircraft X stated that he was climbing due to traffic. I immediately descended aircraft Y to FL370 and told him to expedite. I then climbed aft X to FL410. It appeared that I achieved vertical separation very quickly as aircraft Y reported level at FL370. It appeared that I achieved vertical separation before lateral separation was lost. During this event, numerous radio xmissions were not readable due to many aircraft talking at the same time. Aircraft X was subsequently cleared back to FL390, and aircraft Y stayed at FL370. No conflict alert was activated, no oedp had alerted, and it appeared that I had achieved separation. I heard 3 days later that aircraft Y had filed an near midair collision report. Due to the fact that the ZAB computer was not certified operational, it has yet to be determined the exact 'official' separation that existed. The best estimate so far is a 4.2 NM laterally, and 1 radar hit at about 1100 ft vertically. The voice tapes have not yet been matched to the radar data to verify the time/position of the altitude report. All other radar hits showed that the aircraft were separated. Causal factors: ZAB computer system shut down (no conflict alert/oedp), and inaccurate vector lines in darc mode. Distraction/preoccupation with the fatal accident, and other problems (such as flight plan processing). The shift schedule of 8 hours on, 8 hours off, then 8 more hours on may have caused fatigue to the point of losing awareness. Once I believed that the 2 aircraft were separated, I did not notice the confliction until aircraft X stated that he was climbing. Total time from the time that I thought the 2 aircraft were not going to be in confliction until the incident was approximately 8-9 mins. Before leaving frequency, aircraft Y asked if separation had been lost. I stated 'no' because, on the 200 NM scale that we have to work on the mid, it appeared that separation had been maintained.

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Original NASA ASRS Text

Title: ZAB CTLR ATTEMPTS TO MAINTAIN LEGAL SEPARATION AFTER OPPOSITE DIRECTION, SAME ALT TFC ADVISE OF TCASII MANEUVER.

Narrative: I WAS WORKING THE XD45-XB45 SHIFT, 8 HRS AFTER WORKING A DAY SHIFT. ZAB AND DARC ONLY, AND STILL INVESTIGATING A FATAL CRASH OF AN ACFT THAT JUST CRASHED NEAR THE SECTOR 21/15 BOUNDARY. COORD WAS BEING ACCOMPLISHED WITH THE OMIC AND OTHER AGENCIES REGARDING THE ACCIDENT. ADDITIONALLY, THERE WERE PROBS WITH THE 'FLUSHED FLT PROGRESS STRIPS' AND ALL DATA WAS HAVING TO BE CHKED/PASSED MANUALLY. MODERATE TURB WAS A PROB AT MOST ALTS FROM THE ROCKIES W. AT THIS TIME, ACFT X CHKED IN OVER LVS AT FL390 EBOUND. ACFT Y WAS WBOUND AT FL390. AT ONE POINT, I RAN OUT THE VECTOR LINES AND OBSERVED THAT THE 2 ACFT WOULD PASS APPROX 12 MI APART. AT THAT TIME I WENT BACK TO THE PREVIOUSLY MENTIONED TASKS. ACFT X STATED THAT HE WAS CLBING DUE TO TFC. I IMMEDIATELY DSNDED ACFT Y TO FL370 AND TOLD HIM TO EXPEDITE. I THEN CLBED AFT X TO FL410. IT APPEARED THAT I ACHIEVED VERT SEPARATION VERY QUICKLY AS ACFT Y RPTED LEVEL AT FL370. IT APPEARED THAT I ACHIEVED VERT SEPARATION BEFORE LATERAL SEPARATION WAS LOST. DURING THIS EVENT, NUMEROUS RADIO XMISSIONS WERE NOT READABLE DUE TO MANY ACFT TALKING AT THE SAME TIME. ACFT X WAS SUBSEQUENTLY CLRED BACK TO FL390, AND ACFT Y STAYED AT FL370. NO CONFLICT ALERT WAS ACTIVATED, NO OEDP HAD ALERTED, AND IT APPEARED THAT I HAD ACHIEVED SEPARATION. I HEARD 3 DAYS LATER THAT ACFT Y HAD FILED AN NMAC RPT. DUE TO THE FACT THAT THE ZAB COMPUTER WAS NOT CERTIFIED OPERATIONAL, IT HAS YET TO BE DETERMINED THE EXACT 'OFFICIAL' SEPARATION THAT EXISTED. THE BEST ESTIMATE SO FAR IS A 4.2 NM LATERALLY, AND 1 RADAR HIT AT ABOUT 1100 FT VERTLY. THE VOICE TAPES HAVE NOT YET BEEN MATCHED TO THE RADAR DATA TO VERIFY THE TIME/POS OF THE ALT RPT. ALL OTHER RADAR HITS SHOWED THAT THE ACFT WERE SEPARATED. CAUSAL FACTORS: ZAB COMPUTER SYS SHUT DOWN (NO CONFLICT ALERT/OEDP), AND INACCURATE VECTOR LINES IN DARC MODE. DISTR/PREOCCUPATION WITH THE FATAL ACCIDENT, AND OTHER PROBS (SUCH AS FLT PLAN PROCESSING). THE SHIFT SCHEDULE OF 8 HRS ON, 8 HRS OFF, THEN 8 MORE HRS ON MAY HAVE CAUSED FATIGUE TO THE POINT OF LOSING AWARENESS. ONCE I BELIEVED THAT THE 2 ACFT WERE SEPARATED, I DID NOT NOTICE THE CONFLICTION UNTIL ACFT X STATED THAT HE WAS CLBING. TOTAL TIME FROM THE TIME THAT I THOUGHT THE 2 ACFT WERE NOT GOING TO BE IN CONFLICTION UNTIL THE INCIDENT WAS APPROX 8-9 MINS. BEFORE LEAVING FREQ, ACFT Y ASKED IF SEPARATION HAD BEEN LOST. I STATED 'NO' BECAUSE, ON THE 200 NM SCALE THAT WE HAVE TO WORK ON THE MID, IT APPEARED THAT SEPARATION HAD BEEN MAINTAINED.

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.