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ZBW controller incorrectly judges aircraft performance when in WX, not allowing sufficient lateral separation between A319 descending from holding and a B727 in a holding pattern 1000 ft below.
| Attributes | |
| ACN | 493082 |
| Time | |
| Date | 200011 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : pvd.vortac |
| State Reference | RI |
| Altitude | msl single value : 13000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zbw.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | A319 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : holding cruise : enroute altitude change |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zbw.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : holding cruise : level |
| Route In Use | arrival : holding pattern |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 11 controller time certified in position1 : 0.1 |
| ASRS Report | 493082 |
| 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 : conflict alert aircraft equipment : tcas |
| Resolutory Action | flight crew : took precautionary avoidance action none taken : detected after the fact |
| Miss Distance | horizontal : 22800 vertical : 100 |
| Supplementary | |
| Problem Areas | ATC Human Performance Weather |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Large stack of holding aircraft for boston. Aircraft were being stepped down. Aircraft X at 17000 ft assigned 16000 ft. Aircraft read back 14000 ft. I believed he remembered hearing the number fourteen in his call sign. The aircraft descended to 14000 ft without event. Upon noticing this I vectored aircraft north away from conflicting aircraft at 14000 ft. I then decided to send air carrier X into bos as the next arrival. Aircraft was cleared direct pvd. Moments later I descended him to 11000 ft. Due to the steep turn and reduced speed aircraft came into conflict with an aircraft (Y) holding at 13000 ft.
Original NASA ASRS Text
Title: ZBW CTLR INCORRECTLY JUDGES ACFT PERFORMANCE WHEN IN WX, NOT ALLOWING SUFFICIENT LATERAL SEPARATION BTWN A319 DSNDING FROM HOLDING AND A B727 IN A HOLDING PATTERN 1000 FT BELOW.
Narrative: LARGE STACK OF HOLDING ACFT FOR BOSTON. ACFT WERE BEING STEPPED DOWN. ACFT X AT 17000 FT ASSIGNED 16000 FT. ACFT READ BACK 14000 FT. I BELIEVED HE REMEMBERED HEARING THE NUMBER FOURTEEN IN HIS CALL SIGN. THE ACFT DSNDED TO 14000 FT WITHOUT EVENT. UPON NOTICING THIS I VECTORED ACFT N AWAY FROM CONFLICTING ACFT AT 14000 FT. I THEN DECIDED TO SEND ACR X INTO BOS AS THE NEXT ARR. ACFT WAS CLRED DIRECT PVD. MOMENTS LATER I DSNDED HIM TO 11000 FT. DUE TO THE STEEP TURN AND REDUCED SPD ACFT CAME INTO CONFLICT WITH AN ACFT (Y) HOLDING AT 13000 FT.
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.