Narrative:

Our flight from phx to cos was in a descent to FL210. ZDV directed us to expedite to FL210. Shortly thereafter, ZDV directed a turn 15 degrees left. Since this pointed us at a small thunderstorm cell and we were already in continuous light and moderate turbulence, we requested to maintain present heading for 10 more mi. ZDV denied the request and we turned 15 degrees left. On rolling out of this turn, ZDV cleared us back on original heading. Captain disengaged autoplt to maneuver quickly to avoid the approaching cell. Captain believes clearance was received to cross 35 mi south of cos at 14000 ft MSL and continued descent since this would also help us clear the WX. First officer attempted to confirm clearance with ZDV, but the first break in radio chatter was the, apparent, ZDV supervisor asking us what our previous clearance had been. We asked to confirm 14000 ft. His response was negative FL210. Since we had been cleared to 14000 ft we continued the descent. The call from the supervisor came as we were passing FL190. No other information was requested by ZDV and no TA's called or observed on TCASII. The altitude window on MCP read FL210 when the supervisor called. Neither pilot remembers hearing the altitude alert, probably due to radio saturation, turbulence, cockpit noise, or cockpit communication. Captain believes clearance to 14000 ft was received prior to passing FL210. First officer was unsure and attempting to confirm when the ZDV supervisor called. Radio saturation, WX, moderate turbulence and changing clrncs may have contributed to a breakdown in communications with center and possibly within the cockpit. It is unknown at this time if ZDV is pursuing this incident any further.

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Original NASA ASRS Text

Title: AN ACR MLG FLC, APPARENTLY, STARTS A DSCNT BEFORE THE ZDV CTLR GAVE THEM A DSCNT CLRNC. THE FLC WAS IN MODERATE TURB AND THE RADIO FREQ WAS CONGESTED.

Narrative: OUR FLT FROM PHX TO COS WAS IN A DSCNT TO FL210. ZDV DIRECTED US TO EXPEDITE TO FL210. SHORTLY THEREAFTER, ZDV DIRECTED A TURN 15 DEGS L. SINCE THIS POINTED US AT A SMALL TSTM CELL AND WE WERE ALREADY IN CONTINUOUS LIGHT AND MODERATE TURB, WE REQUESTED TO MAINTAIN PRESENT HDG FOR 10 MORE MI. ZDV DENIED THE REQUEST AND WE TURNED 15 DEGS L. ON ROLLING OUT OF THIS TURN, ZDV CLRED US BACK ON ORIGINAL HDG. CAPT DISENGAGED AUTOPLT TO MANEUVER QUICKLY TO AVOID THE APCHING CELL. CAPT BELIEVES CLRNC WAS RECEIVED TO CROSS 35 MI S OF COS AT 14000 FT MSL AND CONTINUED DSCNT SINCE THIS WOULD ALSO HELP US CLR THE WX. FO ATTEMPTED TO CONFIRM CLRNC WITH ZDV, BUT THE FIRST BREAK IN RADIO CHATTER WAS THE, APPARENT, ZDV SUPVR ASKING US WHAT OUR PREVIOUS CLRNC HAD BEEN. WE ASKED TO CONFIRM 14000 FT. HIS RESPONSE WAS NEGATIVE FL210. SINCE WE HAD BEEN CLRED TO 14000 FT WE CONTINUED THE DSCNT. THE CALL FROM THE SUPVR CAME AS WE WERE PASSING FL190. NO OTHER INFO WAS REQUESTED BY ZDV AND NO TA'S CALLED OR OBSERVED ON TCASII. THE ALT WINDOW ON MCP READ FL210 WHEN THE SUPVR CALLED. NEITHER PLT REMEMBERS HEARING THE ALT ALERT, PROBABLY DUE TO RADIO SATURATION, TURB, COCKPIT NOISE, OR COCKPIT COM. CAPT BELIEVES CLRNC TO 14000 FT WAS RECEIVED PRIOR TO PASSING FL210. FO WAS UNSURE AND ATTEMPTING TO CONFIRM WHEN THE ZDV SUPVR CALLED. RADIO SATURATION, WX, MODERATE TURB AND CHANGING CLRNCS MAY HAVE CONTRIBUTED TO A BREAKDOWN IN COMS WITH CTR AND POSSIBLY WITHIN THE COCKPIT. IT IS UNKNOWN AT THIS TIME IF ZDV IS PURSUING THIS INCIDENT ANY FURTHER.

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.