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ZAU controller recognizes conflict between en route pazt and descending PA31 but actions are insufficient to maintain legal separation.
| Attributes | |
| ACN | 523913 |
| Time | |
| Date | 200109 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : iow.vortac |
| State Reference | IA |
| Altitude | msl bound lower : 5000 msl bound upper : 7000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc |
| Operator | general aviation : personal |
| Make Model Name | PA-31 Navajo Chieftan/Mojave/Navajo T1020 |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | other vortac |
| Flight Phase | descent : approach |
| Route In Use | departure : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zau.artcc |
| Operator | general aviation : personal |
| Make Model Name | PA-23-250 Aztec |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 11 flight time total : 1 |
| ASRS Report | 523913 |
| Person 2 | |
| Affiliation | other |
| Function | flight crew : single pilot |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : published procedure |
| Independent Detector | atc equipment : conflict alert other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 24000 vertical : 400 |
| Supplementary | |
| Problem Areas | ATC Human Performance |
| Primary Problem | ATC Human Performance |
Narrative:
The eastbound navajo at 7000 ft requested lower. (He was inbound to iow.) I issued down 5000 ft and recognized the conflict with the aztec wbound at 6000 ft. I turned both of them 15 degrees left and told the navajo to expedite for traffic. It became apparent this wasn't sufficient to keep 5 mi separation, so I turned the aztec an additional 25 degrees left. I requested a report reaching 5000 ft from the navajo. The additional turn wasn't sufficient either for the closure rates of the 2 twin engine aircraft. Separation was lost. The closest they were: 4 mi, 400 ft.
Original NASA ASRS Text
Title: ZAU CTLR RECOGNIZES CONFLICT BTWN ENRTE PAZT AND DSNDING PA31 BUT ACTIONS ARE INSUFFICIENT TO MAINTAIN LEGAL SEPARATION.
Narrative: THE EBOUND NAVAJO AT 7000 FT REQUESTED LOWER. (HE WAS INBOUND TO IOW.) I ISSUED DOWN 5000 FT AND RECOGNIZED THE CONFLICT WITH THE AZTEC WBOUND AT 6000 FT. I TURNED BOTH OF THEM 15 DEGS L AND TOLD THE NAVAJO TO EXPEDITE FOR TFC. IT BECAME APPARENT THIS WASN'T SUFFICIENT TO KEEP 5 MI SEPARATION, SO I TURNED THE AZTEC AN ADDITIONAL 25 DEGS L. I REQUESTED A RPT REACHING 5000 FT FROM THE NAVAJO. THE ADDITIONAL TURN WASN'T SUFFICIENT EITHER FOR THE CLOSURE RATES OF THE 2 TWIN ENG ACFT. SEPARATION WAS LOST. THE CLOSEST THEY WERE: 4 MI, 400 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.