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Radar separation was lost prior to air carrier Y having air carrier X in sight, resulting in less than standard separation.
| Attributes | |
| ACN | 110545 |
| Time | |
| Date | 198905 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : smo |
| State Reference | CA |
| Altitude | msl bound lower : 5000 msl bound upper : 6000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : lax |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | arrival other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Small Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | cruise other |
| Route In Use | approach : visual |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller radar : 4 |
| ASRS Report | 110545 |
| 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 | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | Other |
| Miss Distance | horizontal : 12000 vertical : 500 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Air carrier X was descended from 10000' to 2500' on downwind for lax. Traffic below and behind was air carrier Y to follow for a visibility approach. Air carrier Y at 5000' did not advise that he had air carrier X in sight prior to losing standard sep. The aircraft subsequently saw the traffic and followed it to the airport on a visibility approach. I did not recall descending the aircraft to 2500', nor missing the pilot's readback. I thought visibility sep did exist. The work level was not difficult, nor was the traffic picture complex.
Original NASA ASRS Text
Title: RADAR SEPARATION WAS LOST PRIOR TO ACR Y HAVING ACR X IN SIGHT, RESULTING IN LESS THAN STANDARD SEPARATION.
Narrative: ACR X WAS DSNDED FROM 10000' TO 2500' ON DOWNWIND FOR LAX. TFC BELOW AND BEHIND WAS ACR Y TO FOLLOW FOR A VIS APCH. ACR Y AT 5000' DID NOT ADVISE THAT HE HAD ACR X IN SIGHT PRIOR TO LOSING STANDARD SEP. THE ACFT SUBSEQUENTLY SAW THE TFC AND FOLLOWED IT TO THE ARPT ON A VIS APCH. I DID NOT RECALL DSNDING THE ACFT TO 2500', NOR MISSING THE PLT'S READBACK. I THOUGHT VIS SEP DID EXIST. THE WORK LEVEL WAS NOT DIFFICULT, NOR WAS THE TFC PICTURE COMPLEX.
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.