Narrative:

ZMA gave us clearance to descend at pilot discretion to FL240. This clearance was at the normal point where we always get our descent clearance into mia from this direction. First officer read back clearance as such. Approximately 1-2 mins later, we started our descent to FL240 and first officer reported our descent to mia. At about FL340, mia asked us our altitude and we reported it as descending through FL340 for FL240. He immediately gave us a turn to the south and told us to climb back to FL350 and said we were not cleared to descend. In the turn we received a TA on TCASII. I kicked off the autoplt and tightened the turn and climbed back to FL350. We picked up the traffic visually during this maneuver and estimate the distance to have been about 4 mi between our aircraft. Rest of flight into mia was uneventful.

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Original NASA ASRS Text

Title: A306 FLC CHALLENGED IN DSCNT BY ZMA, REISSUED CLB CLRNC, BUT ACTIONS, WERE INSUFFICIENT TO MAINTAIN LEGAL SEPARATION.

Narrative: ZMA GAVE US CLRNC TO DSND AT PLT DISCRETION TO FL240. THIS CLRNC WAS AT THE NORMAL POINT WHERE WE ALWAYS GET OUR DSCNT CLRNC INTO MIA FROM THIS DIRECTION. FO READ BACK CLRNC AS SUCH. APPROX 1-2 MINS LATER, WE STARTED OUR DSCNT TO FL240 AND FO RPTED OUR DSCNT TO MIA. AT ABOUT FL340, MIA ASKED US OUR ALT AND WE RPTED IT AS DSNDING THROUGH FL340 FOR FL240. HE IMMEDIATELY GAVE US A TURN TO THE S AND TOLD US TO CLB BACK TO FL350 AND SAID WE WERE NOT CLRED TO DSND. IN THE TURN WE RECEIVED A TA ON TCASII. I KICKED OFF THE AUTOPLT AND TIGHTENED THE TURN AND CLBED BACK TO FL350. WE PICKED UP THE TFC VISUALLY DURING THIS MANEUVER AND ESTIMATE THE DISTANCE TO HAVE BEEN ABOUT 4 MI BTWN OUR ACFT. REST OF FLT INTO MIA WAS UNEVENTFUL.

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.