Narrative:

My aircraft was in contact with mem departure control. We were told to climb and maintain 12000'. We were established on a 90 degree radar vector heading climbing through 6400' when the mem ATC controller told us to maintain 6000'. My first officer advised ATC we were already out of 6500' climbing. As I retarded the throttles and nosed my aircraft over into a descent back to 6000'. For a brief moment there was silence from ATC, then a new voice (the supervisor, I imagine) told us to maintain 6000', that we had 7000' traffic at 11 O'clock. My altimeter indicated 6700' as we advised ATC we had visibility contact with the 7000' traffic. By this time we were descending back to 6000', with no further comments from ATC or us. The ATC controller should have told us to descend to 6000' immediately when he realized we had a possible conflict situation. All of the NASA reports I have submitted in the last 24 months have involved mem low sectors on approach/departure control, with 1 exception. I realize that being based in mem makes the exposure greater, but I always try to be extra cautious in mem airspace.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN ACR-MLG AND UNK ACFT, BOTH ON CLIMBOUT FROM MEM, SAME DIRECTION.

Narrative: MY ACFT WAS IN CONTACT WITH MEM DEP CTL. WE WERE TOLD TO CLB AND MAINTAIN 12000'. WE WERE ESTABLISHED ON A 90 DEG RADAR VECTOR HDG CLBING THROUGH 6400' WHEN THE MEM ATC CTLR TOLD US TO MAINTAIN 6000'. MY F/O ADVISED ATC WE WERE ALREADY OUT OF 6500' CLBING. AS I RETARDED THE THROTTLES AND NOSED MY ACFT OVER INTO A DSCNT BACK TO 6000'. FOR A BRIEF MOMENT THERE WAS SILENCE FROM ATC, THEN A NEW VOICE (THE SUPVR, I IMAGINE) TOLD US TO MAINTAIN 6000', THAT WE HAD 7000' TFC AT 11 O'CLOCK. MY ALTIMETER INDICATED 6700' AS WE ADVISED ATC WE HAD VIS CONTACT WITH THE 7000' TFC. BY THIS TIME WE WERE DSNDING BACK TO 6000', WITH NO FURTHER COMMENTS FROM ATC OR US. THE ATC CTLR SHOULD HAVE TOLD US TO DSND TO 6000' IMMEDIATELY WHEN HE REALIZED WE HAD A POSSIBLE CONFLICT SITUATION. ALL OF THE NASA RPTS I HAVE SUBMITTED IN THE LAST 24 MONTHS HAVE INVOLVED MEM LOW SECTORS ON APCH/DEP CTL, WITH 1 EXCEPTION. I REALIZE THAT BEING BASED IN MEM MAKES THE EXPOSURE GREATER, BUT I ALWAYS TRY TO BE EXTRA CAUTIOUS IN MEM AIRSPACE.

Data retrieved from NASA's ASRS site as of August 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.