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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Air carrier Y descent to occupied altitude had less than standard separation from air carrier X. System error.
| Attributes | |
| ACN | 189591 |
| Time | |
| Date | 199109 |
| Day | Sat |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : dfw |
| State Reference | TX |
| Altitude | msl bound lower : 6000 msl bound upper : 6500 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : dfw |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, High Wing, 2 Turboprop Eng |
| Flight Phase | cruise other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| ASRS Report | 189591 |
| 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 |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 0 vertical : 500 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
I was working the feeder east position. Traffic was very heavy -- more than the 90 flow rate which is what was said to be in effect. Air carrier X, light transport was heading 230 from buj about 30 northeast dfw. He was issued a descent from 60 to 50. I thought I heard a readback. Air carrier Y, large transport about 5-7 mi intrail of air carrier Y (same heading) was given a descent from 90 to 60. A few mins later I noticed the conflict alert. I asked air carrier X if he was at 50. He replied he was at 60. At this point, air carrier Y altitude was 65. The targets were merged. I issued air carrier Y a 290 heading and stop his descent. Air carrier X was then reissued 50. During this time we received a go around from DR1, my handoff man told DR1 we could not take the go around on the east side, to take him to the west side. Next thing we knew we had the go around on our frequency. I feel the tmu's at this facility and at the center need to monitor the traffic flow closer -- especially during a major push such as we were having.
Original NASA ASRS Text
Title: ACR Y DSCNT TO OCCUPIED ALT HAD LTSS FROM ACR X. SYS ERROR.
Narrative: I WAS WORKING THE FEEDER E POS. TFC WAS VERY HVY -- MORE THAN THE 90 FLOW RATE WHICH IS WHAT WAS SAID TO BE IN EFFECT. ACR X, LTT WAS HDG 230 FROM BUJ ABOUT 30 NE DFW. HE WAS ISSUED A DSCNT FROM 60 TO 50. I THOUGHT I HEARD A READBACK. ACR Y, LGT ABOUT 5-7 MI INTRAIL OF ACR Y (SAME HDG) WAS GIVEN A DSCNT FROM 90 TO 60. A FEW MINS LATER I NOTICED THE CONFLICT ALERT. I ASKED ACR X IF HE WAS AT 50. HE REPLIED HE WAS AT 60. AT THIS POINT, ACR Y ALT WAS 65. THE TARGETS WERE MERGED. I ISSUED ACR Y A 290 HDG AND STOP HIS DSCNT. ACR X WAS THEN REISSUED 50. DURING THIS TIME WE RECEIVED A GAR FROM DR1, MY HDOF MAN TOLD DR1 WE COULD NOT TAKE THE GAR ON THE E SIDE, TO TAKE HIM TO THE W SIDE. NEXT THING WE KNEW WE HAD THE GAR ON OUR FREQ. I FEEL THE TMU'S AT THIS FACILITY AND AT THE CENTER NEED TO MONITOR THE TFC FLOW CLOSER -- ESPECIALLY DURING A MAJOR PUSH SUCH AS WE WERE HAVING.
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.