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ZID controller does not observe crossing traffic when issuing descent clearance and incurs a loss of separation.
| Attributes | |
| ACN | 518982 |
| Time | |
| Date | 200107 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : zid.artcc |
| State Reference | IN |
| Altitude | msl bound lower : 26000 msl bound upper : 28000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zid.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : enroute altitude change |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zid.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-500 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller non radar : 2 controller radar : 14 |
| ASRS Report | 518982 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller military : 8 controller radar : 1 |
| ASRS Report | 518983 |
| Events | |
| Anomaly | conflict : airborne less severe inflight encounter : weather non adherence : published procedure non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert other controllera other controllerb |
| Resolutory Action | none taken : insufficient time |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 15000 vertical : 700 |
| Supplementary | |
| Problem Areas | Weather Environmental Factor ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error Intra Facility Coordination Failure |
Narrative:
Traffic was moderate and steady. WX was MVFR to IFR. Aircraft X was going to mdw. Aircraft Y was going to cle at FL270. I descended aircraft X to FL260 to get underneath traffic climbing out of ord. The descent was issued with enough time to get aircraft X under aircraft Y if I would have assigned a rate of descent. But I missed aircraft Y as traffic. Conflict alert did not flash (activate) with enough time to help. Conflict alert activated 24 seconds prior to odep. It seems it should have done so sooner. When it activated, I did not have time to change the situation. Aircraft Y was missed as traffic when I descended the aircraft X. Supplemental information from air carrier 518983: controller issued clearance to aircraft X northbound at FL280 to FL260 and I did not hear it. Aircraft X then descended through the eastbound aircraft Y at FL270. Collision alert did not activate until there was no time to resolve the conflict.
Original NASA ASRS Text
Title: ZID CTLR DOES NOT OBSERVE XING TFC WHEN ISSUING DSCNT CLRNC AND INCURS A LOSS OF SEPARATION.
Narrative: TFC WAS MODERATE AND STEADY. WX WAS MVFR TO IFR. ACFT X WAS GOING TO MDW. ACFT Y WAS GOING TO CLE AT FL270. I DSNDED ACFT X TO FL260 TO GET UNDERNEATH TFC CLBING OUT OF ORD. THE DSCNT WAS ISSUED WITH ENOUGH TIME TO GET ACFT X UNDER ACFT Y IF I WOULD HAVE ASSIGNED A RATE OF DSCNT. BUT I MISSED ACFT Y AS TFC. CONFLICT ALERT DID NOT FLASH (ACTIVATE) WITH ENOUGH TIME TO HELP. CONFLICT ALERT ACTIVATED 24 SECONDS PRIOR TO ODEP. IT SEEMS IT SHOULD HAVE DONE SO SOONER. WHEN IT ACTIVATED, I DID NOT HAVE TIME TO CHANGE THE SIT. ACFT Y WAS MISSED AS TFC WHEN I DSNDED THE ACFT X. SUPPLEMENTAL INFO FROM ACR 518983: CTLR ISSUED CLRNC TO ACFT X NBOUND AT FL280 TO FL260 AND I DID NOT HEAR IT. ACFT X THEN DSNDED THROUGH THE EBOUND ACFT Y AT FL270. COLLISION ALERT DID NOT ACTIVATE UNTIL THERE WAS NO TIME TO RESOLVE THE CONFLICT.
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.