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A center radar controller vectoring 2 aircraft in trail did not slow the second aircraft in sufficient time to prevent loss of separation.
| Attributes | |
| ACN | 398102 |
| Time | |
| Date | 199804 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : cxr |
| State Reference | OH |
| Altitude | msl bound lower : 15800 msl bound upper : 16000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller non radar : 1 controller radar : 9 |
| ASRS Report | 398102 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Miss Distance | horizontal : 22800 vertical : 200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Air carrier X, a cle inbound, was vectored to a 360 degree heading as a delay to avoid holding at cxr inbound fix. He was aware of holding and was operating at reduced airspeed. Air carrier Y, a cle inbound, was turned to a 360 degree heading to follow air carrier X. Air carrier Y was not operating at reduced airspeed. Air carrier X was cleared to descend from FL220 to 15000 ft. Approximately 30 seconds later, air carrier Y requested descent. Air carrier Y was cleared to descend from FL240 to 16000 ft (bottom of shelf airspace). I then concentrated attention on clearing out the holding pattern over cxr. When the conflict alert activated, I realized that air carrier Y had gained considerable distance on air carrier X and was level at 16000 ft. Air carrier X was still in descent to 15000 ft. Air carrier X was turned to a 290 degree heading but separation was already lost. I attempted to get a report arriving at 15000 ft from air carrier X but was unable to do so.
Original NASA ASRS Text
Title: A CTR RADAR CTLR VECTORING 2 ACFT IN TRAIL DID NOT SLOW THE SECOND ACFT IN SUFFICIENT TIME TO PREVENT LOSS OF SEPARATION.
Narrative: ACR X, A CLE INBOUND, WAS VECTORED TO A 360 DEG HDG AS A DELAY TO AVOID HOLDING AT CXR INBOUND FIX. HE WAS AWARE OF HOLDING AND WAS OPERATING AT REDUCED AIRSPD. ACR Y, A CLE INBOUND, WAS TURNED TO A 360 DEG HDG TO FOLLOW ACR X. ACR Y WAS NOT OPERATING AT REDUCED AIRSPD. ACR X WAS CLRED TO DSND FROM FL220 TO 15000 FT. APPROX 30 SECONDS LATER, ACR Y REQUESTED DSCNT. ACR Y WAS CLRED TO DSND FROM FL240 TO 16000 FT (BOTTOM OF SHELF AIRSPACE). I THEN CONCENTRATED ATTN ON CLRING OUT THE HOLDING PATTERN OVER CXR. WHEN THE CONFLICT ALERT ACTIVATED, I REALIZED THAT ACR Y HAD GAINED CONSIDERABLE DISTANCE ON ACR X AND WAS LEVEL AT 16000 FT. ACR X WAS STILL IN DSCNT TO 15000 FT. ACR X WAS TURNED TO A 290 DEG HDG BUT SEPARATION WAS ALREADY LOST. I ATTEMPTED TO GET A RPT ARRIVING AT 15000 FT FROM ACR X BUT WAS UNABLE TO DO SO.
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.