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ZLA controller experienced conflict when aircraft level at FL250 responded to TCAS; climbed above assigned altitude; and conflicted with traffic descending to FL260.
| Attributes | |
| ACN | 704178 |
| Time | |
| Date | 200607 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : bld.vortac |
| State Reference | NV |
| Altitude | msl single value : 25000 |
| Environment | |
| Weather Elements | Thunderstorm |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zla.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-90 Series (DC-9-90) Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : vacating altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zla.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-83 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : vacating altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 12 |
| ASRS Report | 704178 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | conflict : airborne less severe |
| Independent Detector | atc equipment : conflict alert aircraft equipment : tcas other controllera |
| Resolutory Action | controller : issued alert controller : issued new clearance flight crew : took evasive action |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 10000 vertical : 700 |
| Supplementary | |
| Problem Areas | Aircraft FAA |
| Primary Problem | FAA |
Narrative:
The MD90 was northbound FL250; the MD83 sbound descending to FL260. Traffic was issued to both aircraft and both aircraft acknowledged when less than 3 mi separation; the MD90 responded to TCAS alert and climbed FL253; the MD83 was level at this point FL260. Separation was lost even though the pilot was aware the other aircraft was stopping at FL260.
Original NASA ASRS Text
Title: ZLA CTLR EXPERIENCED CONFLICT WHEN ACFT LEVEL AT FL250 RESPONDED TO TCAS; CLBED ABOVE ASSIGNED ALT; AND CONFLICTED WITH TFC DSNDING TO FL260.
Narrative: THE MD90 WAS NBOUND FL250; THE MD83 SBOUND DSNDING TO FL260. TFC WAS ISSUED TO BOTH ACFT AND BOTH ACFT ACKNOWLEDGED WHEN LESS THAN 3 MI SEPARATION; THE MD90 RESPONDED TO TCAS ALERT AND CLBED FL253; THE MD83 WAS LEVEL AT THIS POINT FL260. SEPARATION WAS LOST EVEN THOUGH THE PLT WAS AWARE THE OTHER ACFT WAS STOPPING AT FL260.
Data retrieved from NASA's ASRS site as of January 2009 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.