Narrative:

I was PIC -- operating radio (not flying). First officer flying. The following is the sequence of radio xmissions and aircraft performance that occurred. Atl approach: 'cleared right turn direct lgc, maintain FL220.' readback: 'right turn direct lgc, maintain FL220.' first officer initiated right turn direct lgc. Approach: 'cleared to cross tiroe at 14000 ft/250 KTS, atl altimeter 30.03. Down to FL180 now, expect a turn back to lgc soon.' readback: 'ok, cleared to cross tiroe at 14000 ft/250 KTS, altimeter 30.03, say again the rest.' approach: 'disregard the rest.' readback: 'roger, tiroe at 14000 ft/250 KTS. At this point we assumed the descent was at pilot discretion to cross tiroe at 14000 ft/250 KTS. The confusion came when we were told to 'expect a turn back to lgc soon.' since we were already cleared direct lgc, we thought the controller was probably talking about another airplane. When I asked the controller to 'say again the rest' about the FL180 he replied 'disregard the rest.' we took that to mean we were to disregard the 'descend to FL180, now.' a few min later approach called: 'I need you down through FL180, start down now.' readback: 'yes sir, you told me to disregard the rest,' 'we are in the descent now' or 'we are out of FL220.' approach: 'call through FL200.' readback: 'roger, through 20100 ft and now through FL200.' as we were going through FL200 we received a TCASII TA. -- A yellow diamond at 12 O'clock on the radar scope showing an aircraft climbing 900 ft above us. I feel the confusion began when we were told to expect a clearance 'soon,' a clearance we had already received, thus making us feel the clearance was probably intended for another aircraft. The controller was very busy giving numerous aircraft delaying vectors, altitude, and airspeed changes. I believe the density of traffic in atl during this 'peak' period of time was a contributing factor. The system was saturated. I think the controller should have restated the 'descend now to FL180.' after he told me to 'disregard the rest.' I should have been more inquisitive about a clearance I thought was probably for someone else.

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Original NASA ASRS Text

Title: NON ADHERENCE TO AN 'IMMEDIATE' OR 'START DSCNT NOW' TYPE CLRNC.

Narrative: I WAS PIC -- OPERATING RADIO (NOT FLYING). FO FLYING. THE FOLLOWING IS THE SEQUENCE OF RADIO XMISSIONS AND ACFT PERFORMANCE THAT OCCURRED. ATL APCH: 'CLRED R TURN DIRECT LGC, MAINTAIN FL220.' READBACK: 'R TURN DIRECT LGC, MAINTAIN FL220.' FO INITIATED R TURN DIRECT LGC. APCH: 'CLRED TO CROSS TIROE AT 14000 FT/250 KTS, ATL ALTIMETER 30.03. DOWN TO FL180 NOW, EXPECT A TURN BACK TO LGC SOON.' READBACK: 'OK, CLRED TO CROSS TIROE AT 14000 FT/250 KTS, ALTIMETER 30.03, SAY AGAIN THE REST.' APCH: 'DISREGARD THE REST.' READBACK: 'ROGER, TIROE AT 14000 FT/250 KTS. AT THIS POINT WE ASSUMED THE DSCNT WAS AT PLT DISCRETION TO CROSS TIROE AT 14000 FT/250 KTS. THE CONFUSION CAME WHEN WE WERE TOLD TO 'EXPECT A TURN BACK TO LGC SOON.' SINCE WE WERE ALREADY CLRED DIRECT LGC, WE THOUGHT THE CTLR WAS PROBABLY TALKING ABOUT ANOTHER AIRPLANE. WHEN I ASKED THE CTLR TO 'SAY AGAIN THE REST' ABOUT THE FL180 HE REPLIED 'DISREGARD THE REST.' WE TOOK THAT TO MEAN WE WERE TO DISREGARD THE 'DSND TO FL180, NOW.' A FEW MIN LATER APCH CALLED: 'I NEED YOU DOWN THROUGH FL180, START DOWN NOW.' READBACK: 'YES SIR, YOU TOLD ME TO DISREGARD THE REST,' 'WE ARE IN THE DSCNT NOW' OR 'WE ARE OUT OF FL220.' APCH: 'CALL THROUGH FL200.' READBACK: 'ROGER, THROUGH 20100 FT AND NOW THROUGH FL200.' AS WE WERE GOING THROUGH FL200 WE RECEIVED A TCASII TA. -- A YELLOW DIAMOND AT 12 O'CLOCK ON THE RADAR SCOPE SHOWING AN ACFT CLBING 900 FT ABOVE US. I FEEL THE CONFUSION BEGAN WHEN WE WERE TOLD TO EXPECT A CLRNC 'SOON,' A CLRNC WE HAD ALREADY RECEIVED, THUS MAKING US FEEL THE CLRNC WAS PROBABLY INTENDED FOR ANOTHER ACFT. THE CTLR WAS VERY BUSY GIVING NUMEROUS ACFT DELAYING VECTORS, ALT, AND AIRSPD CHANGES. I BELIEVE THE DENSITY OF TFC IN ATL DURING THIS 'PEAK' PERIOD OF TIME WAS A CONTRIBUTING FACTOR. THE SYS WAS SATURATED. I THINK THE CTLR SHOULD HAVE RESTATED THE 'DSND NOW TO FL180.' AFTER HE TOLD ME TO 'DISREGARD THE REST.' I SHOULD HAVE BEEN MORE INQUISITIVE ABOUT A CLRNC I THOUGHT WAS PROBABLY FOR SOMEONE ELSE.

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.