Narrative:

While en route direct to pke, we were given a descent clearance 'descend now to FL280, pilot's discretion to FL240.' a short time later, we were told 'hurry down to FL280.' when passing through FL285, center said 'hustle down to FL260.' because it was bumpy and about time to descend, I continued to descend to FL240, as we were not told to descend and maintain FL260 -- just hurry to that altitude. The descent clearance to FL240 was not rescinded. While descending to FL240 we received a TCASII (yellow) for an aircraft at FL240, penetrating the 5 mi arc. ATC called and asked if we were at FL260. We said no since we had already descended through FL245 and were about to level at FL240. We saw the aircraft visually and advised ATC. The controller initially seemed to reflect that he had cleared us to FL260 but by the tone of his inquiries seemed to realize that he had indeed cleared us to FL240. We continued to descend and land at san uneventfully. Lesson learned: accept no clearance that utilizes non standard phraseology.

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Original NASA ASRS Text

Title: B767 CAPT DSNDED BELOW THE INTERMEDIATE DSCNT ALT THAT THE ARTCC CTLR BELIEVED THAT HE HAD ASSIGNED, BUT WAS NOT THE ONE LAST ASSIGNED TO THE FLC.

Narrative: WHILE ENRTE DIRECT TO PKE, WE WERE GIVEN A DSCNT CLRNC 'DSND NOW TO FL280, PLT'S DISCRETION TO FL240.' A SHORT TIME LATER, WE WERE TOLD 'HURRY DOWN TO FL280.' WHEN PASSING THROUGH FL285, CTR SAID 'HUSTLE DOWN TO FL260.' BECAUSE IT WAS BUMPY AND ABOUT TIME TO DSND, I CONTINUED TO DSND TO FL240, AS WE WERE NOT TOLD TO DSND AND MAINTAIN FL260 -- JUST HURRY TO THAT ALT. THE DSCNT CLRNC TO FL240 WAS NOT RESCINDED. WHILE DSNDING TO FL240 WE RECEIVED A TCASII (YELLOW) FOR AN ACFT AT FL240, PENETRATING THE 5 MI ARC. ATC CALLED AND ASKED IF WE WERE AT FL260. WE SAID NO SINCE WE HAD ALREADY DSNDED THROUGH FL245 AND WERE ABOUT TO LEVEL AT FL240. WE SAW THE ACFT VISUALLY AND ADVISED ATC. THE CTLR INITIALLY SEEMED TO REFLECT THAT HE HAD CLRED US TO FL260 BUT BY THE TONE OF HIS INQUIRIES SEEMED TO REALIZE THAT HE HAD INDEED CLRED US TO FL240. WE CONTINUED TO DSND AND LAND AT SAN UNEVENTFULLY. LESSON LEARNED: ACCEPT NO CLRNC THAT UTILIZES NON STANDARD PHRASEOLOGY.

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.