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Air carrier Y descent in holding pattern TCASII RA climb had less than standard separation from air carrier X in holding pattern. Evasive action taken.
| Attributes | |
| ACN | 212163 |
| Time | |
| Date | 199206 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : bos |
| State Reference | MA |
| Altitude | msl bound lower : 8000 msl bound upper : 9000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : isp |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | descent other other |
| Route In Use | enroute airway : zbw |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | descent other other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar instruction : instructor |
| Qualification | controller : radar |
| ASRS Report | 212163 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar instruction : trainee |
| Qualification | controller : developmental |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : took evasive action |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 18000 vertical : 500 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
At the time, I was instructing a developmental. Air carrier X was at 9000 ft in a holding pattern over woons intersection. Air carrier X was instructed to descend to 8000 ft and acknowledged leaving 9000 ft. 7 mi southwest of woons, air carrier Y was instructed to descend to 9000 ft. Several mins later, air carrier Y stated 'resolution' and climbed to 9500 ft. What apparently happened was, air carrier X descended slowly and air carrier Y descended quickly resulting in loss of separation. By the air carrier X turning in the holding pattern, 'XXX' was showing instead of an altitude. Confusion over crossing woons time for bos arrs I believe led to confusion, and loss of separation. I believe better tmu coordination, sticking with one program, i.e. Mit, minit. Crossing time restrictions would alleviate distrs.
Original NASA ASRS Text
Title: ACR Y DSCNT IN HOLDING PATTERN TCASII RA CLB HAD LTSS FROM ACR X IN HOLDING PATTERN. EVASIVE ACTION TAKEN.
Narrative: AT THE TIME, I WAS INSTRUCTING A DEVELOPMENTAL. ACR X WAS AT 9000 FT IN A HOLDING PATTERN OVER WOONS INTXN. ACR X WAS INSTRUCTED TO DSND TO 8000 FT AND ACKNOWLEDGED LEAVING 9000 FT. 7 MI SW OF WOONS, ACR Y WAS INSTRUCTED TO DSND TO 9000 FT. SEVERAL MINS LATER, ACR Y STATED 'RESOLUTION' AND CLBED TO 9500 FT. WHAT APPARENTLY HAPPENED WAS, ACR X DSNDED SLOWLY AND ACR Y DSNDED QUICKLY RESULTING IN LOSS OF SEPARATION. BY THE ACR X TURNING IN THE HOLDING PATTERN, 'XXX' WAS SHOWING INSTEAD OF AN ALT. CONFUSION OVER XING WOONS TIME FOR BOS ARRS I BELIEVE LED TO CONFUSION, AND LOSS OF SEPARATION. I BELIEVE BETTER TMU COORD, STICKING WITH ONE PROGRAM, I.E. MIT, MINIT. XING TIME RESTRICTIONS WOULD ALLEVIATE DISTRS.
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.