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After an altitude excursion, a probable misuse of TCASII RA procedures results in a potential conflict between 2 converging B737's.
| Attributes | |
| ACN | 622215 |
| Time | |
| Date | 200303 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : zzz.artcc |
| State Reference | US |
| Altitude | msl bound lower : 31000 msl bound upper : 33400 |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : intermediate altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 189 flight time total : 19100 flight time type : 14500 |
| ASRS Report | 622215 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne critical non adherence : published procedure non adherence : clearance non adherence : company policies |
| Independent Detector | aircraft equipment : tcas other controllera other flight crewa |
| Resolutory Action | controller : issued alert controller : issued new clearance flight crew : took evasive action flight crew : returned to assigned altitude |
| Miss Distance | horizontal : 5000 vertical : 0 |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While cruising at FL310, we received a TCASII advisory 'traffic,' quickly followed by an RA 'climb.' I immediately disconnected the autoplt and autothrottles and responded to the TCASII RA. At the same time, ATC gave instructions to turn right 30 degrees. So after the 'TCASII climb requirement' was being complied with and met, I began the right turn as well. We heard his instructions again. We kept climbing, trying to get away from the conflicting traffic on TCASII when the traffic reversed its path and began climbing toward our flight path. We kept the aircraft climbing to satisfy the TCASII. The traffic continued to get closer to our aircraft, and the traffic passed off our left wing at less than 1 mi. When the conflict was over, our aircraft went from FL310 to FL334 and we advised ATC we were returning to our assigned altitude of FL310. After level at FL310, ATC advised us that the conflicting traffic was a B737 who had caused the conflict. ATC informed us that the aircraft descended into our flight path and then reversed path and began a climb. The conflict aircraft began and continued to climb toward our path while we were climbing in response to our TCASII. I believe that the conflicting traffic 'ignored' their TCASII while trying to return to their assigned altitude.
Original NASA ASRS Text
Title: AFTER AN ALT EXCURSION, A PROBABLE MISUSE OF TCASII RA PROCS RESULTS IN A POTENTIAL CONFLICT BTWN 2 CONVERGING B737'S.
Narrative: WHILE CRUISING AT FL310, WE RECEIVED A TCASII ADVISORY 'TFC,' QUICKLY FOLLOWED BY AN RA 'CLB.' I IMMEDIATELY DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES AND RESPONDED TO THE TCASII RA. AT THE SAME TIME, ATC GAVE INSTRUCTIONS TO TURN R 30 DEGS. SO AFTER THE 'TCASII CLB REQUIREMENT' WAS BEING COMPLIED WITH AND MET, I BEGAN THE R TURN AS WELL. WE HEARD HIS INSTRUCTIONS AGAIN. WE KEPT CLBING, TRYING TO GET AWAY FROM THE CONFLICTING TFC ON TCASII WHEN THE TFC REVERSED ITS PATH AND BEGAN CLBING TOWARD OUR FLT PATH. WE KEPT THE ACFT CLBING TO SATISFY THE TCASII. THE TFC CONTINUED TO GET CLOSER TO OUR ACFT, AND THE TFC PASSED OFF OUR L WING AT LESS THAN 1 MI. WHEN THE CONFLICT WAS OVER, OUR ACFT WENT FROM FL310 TO FL334 AND WE ADVISED ATC WE WERE RETURNING TO OUR ASSIGNED ALT OF FL310. AFTER LEVEL AT FL310, ATC ADVISED US THAT THE CONFLICTING TFC WAS A B737 WHO HAD CAUSED THE CONFLICT. ATC INFORMED US THAT THE ACFT DSNDED INTO OUR FLT PATH AND THEN REVERSED PATH AND BEGAN A CLB. THE CONFLICT ACFT BEGAN AND CONTINUED TO CLB TOWARD OUR PATH WHILE WE WERE CLBING IN RESPONSE TO OUR TCASII. I BELIEVE THAT THE CONFLICTING TFC 'IGNORED' THEIR TCASII WHILE TRYING TO RETURN TO THEIR ASSIGNED ALT.
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.