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A TRACON controller was involved in an operational error when vectoring a DC10 through another controller's airspace, descended the DC10 through the altitude of an E120, 1000 ft below the DC10. At least one other controller was authority/authorized to utilize the same procedure. Both controllers 'quick looked' the adjoining airspace, not seeing each other's transitioning aircraft.
| Attributes | |
| ACN | 386012 |
| Time | |
| Date | 199711 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : ord |
| State Reference | IL |
| Altitude | msl bound lower : 9000 msl bound upper : 10000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : ord |
| Operator | common carrier : air carrier |
| Make Model Name | DC-10 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent : approach descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Brasilia EMB-120 All Series |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller military : 4 controller radar : 15 flight time total : 200 |
| ASRS Report | 386012 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : published procedure |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance none taken : detected after the fact other |
| Consequence | Other |
| Miss Distance | horizontal : 6000 vertical : 400 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Air carrier X, DC10, 40 mi northwest of ord, at 10000 ft inbound to land. Air carrier Y, E120, 4 mi ahead of air carrier X, at 9000 ft also inbound to land, being worked by a different arrival controller, and on a different ARTS III data block tag (F) symbol. Air carrier X was on a (Z) symbol. I was working air carrier X at my position and descended air carrier X to 8000 ft, failing to see air carrier Y ahead and to the left of air carrier X's position. I was not 'quick looking' all of the (F) position symbols, and air carrier X and air carrier Y's tags were overlapped at the time of descent. Air carrier X was slowly overtaking air carrier Y. The resultant loss of separation became air carrier X 1 NM behind air carrier Y at 9400 ft. Air carrier Y was at 9000 ft before air carrier X saw the traffic and was told to maintain visual separation. I had just come in for the shift and had been working this position for only 1 hour and 10 mins. My handoff controller advised me to watch for and miss aircraft on the 'F' symbol, being vectored to another runway. I simply thought I had seen all the applicable traffic before descending air carrier X, but did not see air carrier Y. I should have kept air carrier X at 10000 ft, as there was no huge rush to descend him yet. I was doing this as a repetitive function of continuity for all my aircraft.
Original NASA ASRS Text
Title: A TRACON CTLR WAS INVOLVED IN AN OPERROR WHEN VECTORING A DC10 THROUGH ANOTHER CTLR'S AIRSPACE, DSNDED THE DC10 THROUGH THE ALT OF AN E120, 1000 FT BELOW THE DC10. AT LEAST ONE OTHER CTLR WAS AUTH TO UTILIZE THE SAME PROC. BOTH CTLRS 'QUICK LOOKED' THE ADJOINING AIRSPACE, NOT SEEING EACH OTHER'S TRANSITIONING ACFT.
Narrative: ACR X, DC10, 40 MI NW OF ORD, AT 10000 FT INBOUND TO LAND. ACR Y, E120, 4 MI AHEAD OF ACR X, AT 9000 FT ALSO INBOUND TO LAND, BEING WORKED BY A DIFFERENT ARR CTLR, AND ON A DIFFERENT ARTS III DATA BLOCK TAG (F) SYMBOL. ACR X WAS ON A (Z) SYMBOL. I WAS WORKING ACR X AT MY POS AND DSNDED ACR X TO 8000 FT, FAILING TO SEE ACR Y AHEAD AND TO THE L OF ACR X'S POS. I WAS NOT 'QUICK LOOKING' ALL OF THE (F) POS SYMBOLS, AND ACR X AND ACR Y'S TAGS WERE OVERLAPPED AT THE TIME OF DSCNT. ACR X WAS SLOWLY OVERTAKING ACR Y. THE RESULTANT LOSS OF SEPARATION BECAME ACR X 1 NM BEHIND ACR Y AT 9400 FT. ACR Y WAS AT 9000 FT BEFORE ACR X SAW THE TFC AND WAS TOLD TO MAINTAIN VISUAL SEPARATION. I HAD JUST COME IN FOR THE SHIFT AND HAD BEEN WORKING THIS POS FOR ONLY 1 HR AND 10 MINS. MY HDOF CTLR ADVISED ME TO WATCH FOR AND MISS ACFT ON THE 'F' SYMBOL, BEING VECTORED TO ANOTHER RWY. I SIMPLY THOUGHT I HAD SEEN ALL THE APPLICABLE TFC BEFORE DSNDING ACR X, BUT DID NOT SEE ACR Y. I SHOULD HAVE KEPT ACR X AT 10000 FT, AS THERE WAS NO HUGE RUSH TO DSND HIM YET. I WAS DOING THIS AS A REPETITIVE FUNCTION OF CONTINUITY FOR ALL MY ACFT.
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.