Narrative:

Positive coordination from atl ARTCC high rock sector (R47) with atl ARTCC clt high sector (R33) for medium large transport X to be taken off course and descended below the airspace of R47 at approximately XA02 pm. Soon after coordination medium large transport X was descended to base altitude of R47 airspace by R47 controller (FL350). At XA0540 aircraft changed to clt high R33. R33 controller decided to use speed control and not take medium large transport X off course. This was not coordinated with R47 controller. R47 controller continued to monitor progress of medium large transport X and had several visual references that seemed to confirm coordinated action was indeed being done. These visual references were false due to poor tracking and loss of mode C (XXX in full data block). When R33 controller retracked medium large transport X it was still at FL350 and head on with medium large transport Y. R47 controller turned medium large transport Y to west heading believing that R33 would turn medium large transport X to south. Unfortunately, R33 turned medium large transport X to north creating a head on situation. At last moment R47 controller issued climb to medium large transport X and the aircraft just missed. Why? R33 did not coordinate new plan, did not coordinate left turn for medium large transport X, did not descend aircraft in timely fashion. Contributing factors: east coast flight plan first day, poor briefing on changes, including airspace changes in wash ARTCC. Both center sectors were 1 person and under the unusual circumstances should have been 2 person. Change of plan for descent (speed vs off course vector) not coordinated. Poor tracking by radar and computer (data block not in position of the aircraft and no model). When conflict alert went off action of R47 and R33 controller not coordinated. Supplemental information from acn 84098: there are 3 factors I believe contributed to this incident. 1) the sector 47 controller failed to either point out or resolve potential conflicting traffic for medium large transport X prior to transferring control of the aircraft. He also did not determine which direction medium large transport X would be turning for descent prior to turning his traffic for sep. 2) the proximity of the aircraft to the clt/maiden, nc, radar site was responsible for the target jump. Had the target on medium large transport X remained properly tracked, the C/a would have gone off sooner possibly providing enough time to further separate the aircraft. This is a very common occurrence in this area and has been documented on numerous occasions. This radar strike routinely causes split beacons, multiple targets or ring around, ghost targets and complete mistracks of aircraft. 3) the expanded east coast plan which became effective 3/10/88 is responsible for numerous aircraft transitioning altitude and stratums just prior to the wash center boundary. No provision is made for aircraft on the same routine already operating at lower altitudes. Sector 33 receives no computer strip generation on aircraft operating above FL330. The controllers are only aware of aircraft that must be descended and spaced to meet the letter of agreement when they are either handed off or flight plan information is manually forced to them by the controllers at sector 47. Supplemental information from acn 83352: passing through 300 degrees we saw traffic at 12 O'clock, co altitude, in a left hand turn about 3 mi. After a couple of seconds we saw that we were on a direct collision course. We waited a few seconds to ascertain whether the other aircraft was going to take any evasive actions. It appeared that he wasn't, so we immediately climbed about 400' passing directly over the other aircraft. If we had not seen the other aircraft, we feel certain we would have had a collision. Callback conversation with reporter revealed the following: reporter (R47 controller) stated that he felt the responsibility for this system error and potential midair disaster belonged to the controller in R33. After a lengthy conversation with reporter, and another reading of the report from R33, analyst can only conclude that the actions of R47 were the major cause of this incident. R47 was the only controller that had information about the 3 elements in this loss of sep. First, when 47 coordinated with 33 about what to do about the pending conflict between medium large transport X and medium large transport Y, he was informed that 33 had medium large transport Z directly below medium large transport X and could not descend X in a timely manner. At that time, 47 should have coordinated a positive plan of action with 33, including directions of turns and either speed or vector actions that would have preserved the sep. Facility review of the error concluded that of the 4 controllers involved, reporter (R47 #2) had the best opportunity to resolve this pending conflict. As stated by 1 pilot reporter, had he not seen the other aircraft, a midair collision would have occurred. No doubt, the problems cited by both controllers had a contributory effect during this error. Analyst feels however, that regardless of rdp problems and the unfamiliarity with the new east coast plan, the R47 controller would have prevented the conflict if he had taken positive action to provide everyone with vectors to prevent the loss of sep.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION AND NMAC BETWEEN 2 ACR-MLGS ON SAME AIRWAY, OPPOSITE DIRECTION, AT SAME ALT.

Narrative: POSITIVE COORD FROM ATL ARTCC HIGH ROCK SECTOR (R47) WITH ATL ARTCC CLT HIGH SECTOR (R33) FOR MLG X TO BE TAKEN OFF COURSE AND DSNDED BELOW THE AIRSPACE OF R47 AT APPROX XA02 PM. SOON AFTER COORD MLG X WAS DSNDED TO BASE ALT OF R47 AIRSPACE BY R47 CTLR (FL350). AT XA0540 ACFT CHANGED TO CLT HIGH R33. R33 CTLR DECIDED TO USE SPD CTL AND NOT TAKE MLG X OFF COURSE. THIS WAS NOT COORDINATED WITH R47 CTLR. R47 CTLR CONTINUED TO MONITOR PROGRESS OF MLG X AND HAD SEVERAL VISUAL REFERENCES THAT SEEMED TO CONFIRM COORDINATED ACTION WAS INDEED BEING DONE. THESE VISUAL REFERENCES WERE FALSE DUE TO POOR TRACKING AND LOSS OF MODE C (XXX IN FULL DATA BLOCK). WHEN R33 CTLR RETRACKED MLG X IT WAS STILL AT FL350 AND HEAD ON WITH MLG Y. R47 CTLR TURNED MLG Y TO W HDG BELIEVING THAT R33 WOULD TURN MLG X TO S. UNFORTUNATELY, R33 TURNED MLG X TO N CREATING A HEAD ON SITUATION. AT LAST MOMENT R47 CTLR ISSUED CLB TO MLG X AND THE ACFT JUST MISSED. WHY? R33 DID NOT COORDINATE NEW PLAN, DID NOT COORDINATE LEFT TURN FOR MLG X, DID NOT DSND ACFT IN TIMELY FASHION. CONTRIBUTING FACTORS: E COAST FLT PLAN FIRST DAY, POOR BRIEFING ON CHANGES, INCLUDING AIRSPACE CHANGES IN WASH ARTCC. BOTH CTR SECTORS WERE 1 PERSON AND UNDER THE UNUSUAL CIRCUMSTANCES SHOULD HAVE BEEN 2 PERSON. CHANGE OF PLAN FOR DSCNT (SPD VS OFF COURSE VECTOR) NOT COORDINATED. POOR TRACKING BY RADAR AND COMPUTER (DATA BLOCK NOT IN POS OF THE ACFT AND NO MODEL). WHEN CONFLICT ALERT WENT OFF ACTION OF R47 AND R33 CTLR NOT COORDINATED. SUPPLEMENTAL INFO FROM ACN 84098: THERE ARE 3 FACTORS I BELIEVE CONTRIBUTED TO THIS INCIDENT. 1) THE SECTOR 47 CTLR FAILED TO EITHER POINT OUT OR RESOLVE POTENTIAL CONFLICTING TFC FOR MLG X PRIOR TO TRANSFERRING CTL OF THE ACFT. HE ALSO DID NOT DETERMINE WHICH DIRECTION MLG X WOULD BE TURNING FOR DSCNT PRIOR TO TURNING HIS TFC FOR SEP. 2) THE PROX OF THE ACFT TO THE CLT/MAIDEN, NC, RADAR SITE WAS RESPONSIBLE FOR THE TARGET JUMP. HAD THE TARGET ON MLG X REMAINED PROPERLY TRACKED, THE C/A WOULD HAVE GONE OFF SOONER POSSIBLY PROVIDING ENOUGH TIME TO FURTHER SEPARATE THE ACFT. THIS IS A VERY COMMON OCCURRENCE IN THIS AREA AND HAS BEEN DOCUMENTED ON NUMEROUS OCCASIONS. THIS RADAR STRIKE ROUTINELY CAUSES SPLIT BEACONS, MULTIPLE TARGETS OR RING AROUND, GHOST TARGETS AND COMPLETE MISTRACKS OF ACFT. 3) THE EXPANDED E COAST PLAN WHICH BECAME EFFECTIVE 3/10/88 IS RESPONSIBLE FOR NUMEROUS ACFT TRANSITIONING ALT AND STRATUMS JUST PRIOR TO THE WASH CTR BOUNDARY. NO PROVISION IS MADE FOR ACFT ON THE SAME ROUTINE ALREADY OPERATING AT LOWER ALTS. SECTOR 33 RECEIVES NO COMPUTER STRIP GENERATION ON ACFT OPERATING ABOVE FL330. THE CTLRS ARE ONLY AWARE OF ACFT THAT MUST BE DSNDED AND SPACED TO MEET THE LETTER OF AGREEMENT WHEN THEY ARE EITHER HANDED OFF OR FLT PLAN INFO IS MANUALLY FORCED TO THEM BY THE CTLRS AT SECTOR 47. SUPPLEMENTAL INFO FROM ACN 83352: PASSING THROUGH 300 DEGS WE SAW TFC AT 12 O'CLOCK, CO ALT, IN A LEFT HAND TURN ABOUT 3 MI. AFTER A COUPLE OF SECS WE SAW THAT WE WERE ON A DIRECT COLLISION COURSE. WE WAITED A FEW SECS TO ASCERTAIN WHETHER THE OTHER ACFT WAS GOING TO TAKE ANY EVASIVE ACTIONS. IT APPEARED THAT HE WASN'T, SO WE IMMEDIATELY CLBED ABOUT 400' PASSING DIRECTLY OVER THE OTHER ACFT. IF WE HAD NOT SEEN THE OTHER ACFT, WE FEEL CERTAIN WE WOULD HAVE HAD A COLLISION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR (R47 CTLR) STATED THAT HE FELT THE RESPONSIBILITY FOR THIS SYSTEM ERROR AND POTENTIAL MIDAIR DISASTER BELONGED TO THE CTLR IN R33. AFTER A LENGTHY CONVERSATION WITH RPTR, AND ANOTHER READING OF THE RPT FROM R33, ANALYST CAN ONLY CONCLUDE THAT THE ACTIONS OF R47 WERE THE MAJOR CAUSE OF THIS INCIDENT. R47 WAS THE ONLY CTLR THAT HAD INFO ABOUT THE 3 ELEMENTS IN THIS LOSS OF SEP. FIRST, WHEN 47 COORDINATED WITH 33 ABOUT WHAT TO DO ABOUT THE PENDING CONFLICT BTWN MLG X AND MLG Y, HE WAS INFORMED THAT 33 HAD MLG Z DIRECTLY BELOW MLG X AND COULD NOT DSND X IN A TIMELY MANNER. AT THAT TIME, 47 SHOULD HAVE COORDINATED A POSITIVE PLAN OF ACTION WITH 33, INCLUDING DIRECTIONS OF TURNS AND EITHER SPD OR VECTOR ACTIONS THAT WOULD HAVE PRESERVED THE SEP. FAC REVIEW OF THE ERROR CONCLUDED THAT OF THE 4 CTLRS INVOLVED, RPTR (R47 #2) HAD THE BEST OPPORTUNITY TO RESOLVE THIS PENDING CONFLICT. AS STATED BY 1 PLT RPTR, HAD HE NOT SEEN THE OTHER ACFT, A MIDAIR COLLISION WOULD HAVE OCCURRED. NO DOUBT, THE PROBS CITED BY BOTH CTLRS HAD A CONTRIBUTORY EFFECT DURING THIS ERROR. ANALYST FEELS HOWEVER, THAT REGARDLESS OF RDP PROBS AND THE UNFAMILIARITY WITH THE NEW EAST COAST PLAN, THE R47 CTLR WOULD HAVE PREVENTED THE CONFLICT IF HE HAD TAKEN POSITIVE ACTION TO PROVIDE EVERYONE WITH VECTORS TO PREVENT THE LOSS OF SEP.

Data retrieved from NASA's ASRS site as of August 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.