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Air carrier was descended through an altitude occupied by another air carrier. Attempts to vector aircraft were not sufficient enough to prevent less than standard separation.
| Attributes | |
| ACN | 113358 |
| Time | |
| Date | 198906 |
| Day | Sun |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : buf |
| State Reference | NY |
| Altitude | msl bound lower : 20000 msl bound upper : 21000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | non adherence : published procedure non adherence : required legal separation other spatial deviation |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Miss Distance | horizontal : 18000 vertical : 200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Air carrier X departed yyz southbound and was climbing to FL230, requested FL310. Air carrier Y was inbound to buf from ord, descending to FL240. Air carrier Y was then cleared to 11,000 and air carrier X was cleared to FL240. About 60-90 second before loss of separation, both aircraft were turned 30 degree right. I then selected a 5 mi polygon on air carrier Y. At this time I realized that the aircraft were closer than I thought and I attempted to stop air carrier X at FL200 and air carrier Y at FL210. Air carrier Y was already through FL210 and stopped at FL202. Resulting separation was about 3 mi and 200'. A factor in misjudging the situation was a recent change in airspace which changed the range on the radar display from 100 to 75 mile radius. This caused me to think that I had more time and mileage than I did.
Original NASA ASRS Text
Title: ACR WAS DESCENDED THROUGH AN ALT OCCUPIED BY ANOTHER ACR. ATTEMPTS TO VECTOR ACFT WERE NOT SUFFICIENT ENOUGH TO PREVENT LESS THAN STANDARD SEPARATION.
Narrative: ACR X DEPARTED YYZ SBND AND WAS CLIMBING TO FL230, REQUESTED FL310. ACR Y WAS INBND TO BUF FROM ORD, DESCENDING TO FL240. ACR Y WAS THEN CLRED TO 11,000 AND ACR X WAS CLRED TO FL240. ABOUT 60-90 SEC BEFORE LOSS OF SEPARATION, BOTH ACFT WERE TURNED 30 DEG RIGHT. I THEN SELECTED A 5 MI POLYGON ON ACR Y. AT THIS TIME I REALIZED THAT THE ACFT WERE CLOSER THAN I THOUGHT AND I ATTEMPTED TO STOP ACR X AT FL200 AND ACR Y AT FL210. ACR Y WAS ALREADY THROUGH FL210 AND STOPPED AT FL202. RESULTING SEPARATION WAS ABOUT 3 MI AND 200'. A FACTOR IN MISJUDGING THE SITUATION WAS A RECENT CHANGE IN AIRSPACE WHICH CHANGED THE RANGE ON THE RADAR DISPLAY FROM 100 TO 75 MILE RADIUS. THIS CAUSED ME TO THINK THAT I HAD MORE TIME AND MILEAGE THAN I DID.
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.