Flight crew of a B757 responded to another company aircraft's clearance and started descent.

Attributes
ACN	458396
Time
Date	199912
Day	Tue
Local Time Of Day	0601 To 1200
Place
State Reference	TX
Altitude	msl bound lower : 29000 msl bound upper : 31000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	arrival star : ukw.ukw5
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : vacating altitude
Route In Use	arrival star : ukw.ukw5
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	458396
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence other
Independent Detector	other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

On arrival to dfw today we accepted a clearance for descent FL310 to FL240 by ATC prior to the ganja intersection on the bowie arrival. Passing FL290 we were asked by ATC what our altitude was and we reported FL290 descending to FL240. ATC informed us that the descent was for another aircraft with a similar call sign. He instructed us to continue descent to FL280, which we did. While accepting the clearance, we reported accepting the clearance and departing FL310 for FL240. ATC did not catch the call sign deviation nor did we until the call at FL290. We did not see any aircraft on TCASII which conflicted with us.

Original NASA ASRS Text

Title: FLC OF A B757 RESPONDED TO ANOTHER COMPANY ACFT'S CLRNC AND STARTED DSCNT.

Narrative: ON ARR TO DFW TODAY WE ACCEPTED A CLRNC FOR DSCNT FL310 TO FL240 BY ATC PRIOR TO THE GANJA INTXN ON THE BOWIE ARR. PASSING FL290 WE WERE ASKED BY ATC WHAT OUR ALT WAS AND WE RPTED FL290 DSNDING TO FL240. ATC INFORMED US THAT THE DSCNT WAS FOR ANOTHER ACFT WITH A SIMILAR CALL SIGN. HE INSTRUCTED US TO CONTINUE DSCNT TO FL280, WHICH WE DID. WHILE ACCEPTING THE CLRNC, WE RPTED ACCEPTING THE CLRNC AND DEPARTING FL310 FOR FL240. ATC DID NOT CATCH THE CALL SIGN DEV NOR DID WE UNTIL THE CALL AT FL290. WE DID NOT SEE ANY ACFT ON TCASII WHICH CONFLICTED WITH US.

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.