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C90 controller experienced operational error at 10000 ft when descent rate of one aircraft was slower than anticipated and resulted in a loss of separation.
| Attributes | |
| ACN | 685140 |
| Time | |
| Date | 200601 |
| Place | |
| Locale Reference | atc facility : c90.tracon |
| State Reference | IL |
| Altitude | msl bound lower : 4000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : c90.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | Regional Jet 700 ER&LR |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Route In Use | arrival : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tracon : c90.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | Regional Jet 700 ER&LR |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Route In Use | arrival : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : military controller : radar |
| Experience | controller military : 7.5 controller radar : 2 |
| ASRS Report | 685140 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert other controllera |
| Resolutory Action | controller : issued alert controller : issued new clearance |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 6000 vertical : 800 |
| Supplementary | |
| Problem Areas | ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Aircraft #1 was at 10000 ft at 210 KTS. Aircraft #2 was at 7000 ft at 170 KTS. Aircraft #2 was descended to 4000 ft on a northeast heading. Aircraft #1 was told to reduce speed to 170 KTS then descend to 5000 ft on an east heading. Aircraft #2 did not descend at an average RAT and ended up 800 ft vertical from aircraft #2 and 1 mi lateral. No action was taken because neither controller involved thought the situation was an issue of safety.
Original NASA ASRS Text
Title: C90 CTLR EXPERIENCED OPERROR AT 10000 FT WHEN DSCNT RATE OF ONE ACFT WAS SLOWER THAN ANTICIPATED AND RESULTED IN A LOSS OF SEPARATION.
Narrative: ACFT #1 WAS AT 10000 FT AT 210 KTS. ACFT #2 WAS AT 7000 FT AT 170 KTS. ACFT #2 WAS DSNDED TO 4000 FT ON A NE HDG. ACFT #1 WAS TOLD TO REDUCE SPD TO 170 KTS THEN DSND TO 5000 FT ON AN E HDG. ACFT #2 DID NOT DSND AT AN AVERAGE RAT AND ENDED UP 800 FT VERT FROM ACFT #2 AND 1 MI LATERAL. NO ACTION WAS TAKEN BECAUSE NEITHER CTLR INVOLVED THOUGHT THE SIT WAS AN ISSUE OF SAFETY.
Data retrieved from NASA's ASRS site as of January 2009 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.