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Loss of separation between an air carrier descending through FL210 and other aircraft presumed to be at or climbing to FL200. Reporter stated they received a TCASII RA to descend and were clear of the traffic at FL195.
| Attributes | |
| ACN | 388851 |
| Time | |
| Date | 199712 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : msy |
| State Reference | LA |
| Altitude | msl bound lower : 19500 msl bound upper : 21000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zhu tower : pdk |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | other : unknown |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : instrument pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 200 flight time total : 15500 flight time type : 10000 |
| ASRS Report | 388851 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action other |
| Consequence | Other |
| Miss Distance | horizontal : 15000 vertical : 0 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Had clearance to 16000 ft, passing through FL210 at approximately 2500 FPM descent, we were told to maintain FL210. By this time we were approaching FL200 and I questioned the clearance as we started to slow the descent and climb back to FL210. As we did, we received an RA with a 2000 FPM descent command. With the traffic not in sight we followed the command. At approximately FL195 we were clear of the conflict and advised ATC. We were then reclred to 11000 ft. It looked to us as the initial clearance, with our rate of descent, would have kept us clear of any conflict. The conflict arose with the reclearance to maintain an altitude we had just passed through.
Original NASA ASRS Text
Title: LOSS OF SEPARATION BTWN AN ACR DSNDING THROUGH FL210 AND OTHER ACFT PRESUMED TO BE AT OR CLBING TO FL200. RPTR STATED THEY RECEIVED A TCASII RA TO DSND AND WERE CLR OF THE TFC AT FL195.
Narrative: HAD CLRNC TO 16000 FT, PASSING THROUGH FL210 AT APPROX 2500 FPM DSCNT, WE WERE TOLD TO MAINTAIN FL210. BY THIS TIME WE WERE APCHING FL200 AND I QUESTIONED THE CLRNC AS WE STARTED TO SLOW THE DSCNT AND CLB BACK TO FL210. AS WE DID, WE RECEIVED AN RA WITH A 2000 FPM DSCNT COMMAND. WITH THE TFC NOT IN SIGHT WE FOLLOWED THE COMMAND. AT APPROX FL195 WE WERE CLR OF THE CONFLICT AND ADVISED ATC. WE WERE THEN RECLRED TO 11000 FT. IT LOOKED TO US AS THE INITIAL CLRNC, WITH OUR RATE OF DSCNT, WOULD HAVE KEPT US CLR OF ANY CONFLICT. THE CONFLICT AROSE WITH THE RECLEARANCE TO MAINTAIN AN ALT WE HAD JUST PASSED THROUGH.
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.