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An apparent blocked transmission prevented receipt of a descent clearance revision. Activation of TCASII resolved the traffic conflict that resulted.
| Attributes | |
| ACN | 574339 |
| Time | |
| Date | 200302 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| State Reference | SC |
| Altitude | msl bound lower : 33000 msl bound upper : 35400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : enroute altitude change |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : ztl.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 156 flight time total : 14000 flight time type : 2500 |
| ASRS Report | 574339 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | conflict : airborne critical non adherence : required legal separation other anomaly other |
| Independent Detector | aircraft equipment : tcas other controllera |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance ATC Human Performance |
| Primary Problem | ATC Human Performance |
Narrative:
Descending from FL390 to FL350, thrust levers at idle due to turbulence at FL390. At about FL364, heard 'flight maintain FL370 (transmission blocked), I slowed descent. Our call sign was air carrier X. ZTL called for aircraft Y flight to maintain FL330. They were cleared to FL350 also. We acknowledged next transmission from ATC to maintain FL370. TCASII gave us a TA (visually acquired), RA 'monitor vertical speed,' then RA 'climb, crossing, climb.' our altitude FL354, then climb, then return to FL350. This of course transpired very quickly and we returned to FL350. Blocked xmissions, human factors, technology -- thanks TCASII.
Original NASA ASRS Text
Title: AN APPARENT BLOCKED XMISSION PREVENTED RECEIPT OF A DSCNT CLRNC REVISION. ACTIVATION OF TCASII RESOLVED THE TFC CONFLICT THAT RESULTED.
Narrative: DSNDING FROM FL390 TO FL350, THRUST LEVERS AT IDLE DUE TO TURB AT FL390. AT ABOUT FL364, HEARD 'FLT MAINTAIN FL370 (XMISSION BLOCKED), I SLOWED DSCNT. OUR CALL SIGN WAS ACR X. ZTL CALLED FOR ACFT Y FLT TO MAINTAIN FL330. THEY WERE CLRED TO FL350 ALSO. WE ACKNOWLEDGED NEXT XMISSION FROM ATC TO MAINTAIN FL370. TCASII GAVE US A TA (VISUALLY ACQUIRED), RA 'MONITOR VERT SPD,' THEN RA 'CLB, XING, CLB.' OUR ALT FL354, THEN CLB, THEN RETURN TO FL350. THIS OF COURSE TRANSPIRED VERY QUICKLY AND WE RETURNED TO FL350. BLOCKED XMISSIONS, HUMAN FACTORS, TECHNOLOGY -- THANKS TCASII.
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.