Narrative:

Approaching sie at FL330, requested descent on ZDC frequency 128.52. Controller issued clearance down to FL240 which the first officer acknowledged. Out of FL300, controller issued turn to a heading of 090 degrees and advised of climbing traffic 5-7 mi off left side. Advised visual on the traffic and then as we descended out of FL290, controller questioned our assigned altitude. We advised 'cleared down to FL240.' controller advised to maintain FL290 and switch to frequency 133.12. Controller on 133.12 cleared us direct to hoggs intersection and stated that we must have taken company clearance by mistake. We think there was a company flight clearance on frequency 128.52, but we never heard any communication between them and the controller until we were switching frequency from 128.52 to 133.12.

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Original NASA ASRS Text

Title: AFTER REQUESTING A LOWER ALT, FLT CREW OF A-300 MISTAKENLY TOOK DSCNT CLRNC INTENDED FOR ANOTHER ACFT.

Narrative: APCHING SIE AT FL330, REQUESTED DSCNT ON ZDC FREQ 128.52. CTLR ISSUED CLRNC DOWN TO FL240 WHICH THE FO ACKNOWLEDGED. OUT OF FL300, CTLR ISSUED TURN TO A HDG OF 090 DEGS AND ADVISED OF CLBING TFC 5-7 MI OFF L SIDE. ADVISED VISUAL ON THE TFC AND THEN AS WE DSNDED OUT OF FL290, CTLR QUESTIONED OUR ASSIGNED ALT. WE ADVISED 'CLEARED DOWN TO FL240.' CTLR ADVISED TO MAINTAIN FL290 AND SWITCH TO FREQ 133.12. CTLR ON 133.12 CLRED US DIRECT TO HOGGS INTXN AND STATED THAT WE MUST HAVE TAKEN COMPANY CLRNC BY MISTAKE. WE THINK THERE WAS A COMPANY FLT CLRNC ON FREQ 128.52, BUT WE NEVER HEARD ANY COM BTWN THEM AND THE CTLR UNTIL WE WERE SWITCHING FREQ FROM 128.52 TO 133.12.

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.