B737 with cvg TRACON leaves altitude because of similar call sign confusion.

Attributes
ACN	607967
Time
Date	200402
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : cvg.vortac
State Reference	OH
Altitude	msl bound lower : 10700 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : cvg.tracon tower : oak.tower
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent : approach
Route In Use	arrival star : mosey
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : cvg.tracon
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : flight engineer pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 141 flight time total : 10679 flight time type : 895
ASRS Report	607967
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued advisory controller : issued new clearance flight crew : returned to assigned altitude flight crew : became reoriented
Supplementary
Problem Areas	Company ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During night (VFR) arrival into cincinnati, oh, on mosey 5 arrival, we had a minor altitude deviation. Autoplt was on, I was the PF, and we were talking to cvg approach. We were level at 11000 ft inbound to cvg. We received descent clearance to 7000 ft. After we acknowledged and began descent, the controller immediately called back to say, 'just to confirm that was for air carrier xxyy, down to 7000 ft.' (we were air carrier xxyx). We began climb back to 11000 ft (reached 10700 ft) and controller confirmed 'air carrier xxyx, remain at 11000 ft.' our readback might have been covered by simultaneous aircraft, or the controller may have misspoken because he immediately responded with the confirmation call. We had just switched frequencys and hadn't been hearing the similar call sign before. We were also at the end of an 11 1/2 hour crew day.

Original NASA ASRS Text

Title: B737 WITH CVG TRACON LEAVES ALT BECAUSE OF SIMILAR CALL SIGN CONFUSION.

Narrative: DURING NIGHT (VFR) ARR INTO CINCINNATI, OH, ON MOSEY 5 ARR, WE HAD A MINOR ALTDEV. AUTOPLT WAS ON, I WAS THE PF, AND WE WERE TALKING TO CVG APCH. WE WERE LEVEL AT 11000 FT INBOUND TO CVG. WE RECEIVED DSCNT CLRNC TO 7000 FT. AFTER WE ACKNOWLEDGED AND BEGAN DSCNT, THE CTLR IMMEDIATELY CALLED BACK TO SAY, 'JUST TO CONFIRM THAT WAS FOR ACR XXYY, DOWN TO 7000 FT.' (WE WERE ACR XXYX). WE BEGAN CLB BACK TO 11000 FT (REACHED 10700 FT) AND CTLR CONFIRMED 'ACR XXYX, REMAIN AT 11000 FT.' OUR READBACK MIGHT HAVE BEEN COVERED BY SIMULTANEOUS ACFT, OR THE CTLR MAY HAVE MISSPOKEN BECAUSE HE IMMEDIATELY RESPONDED WITH THE CONFIRMATION CALL. WE HAD JUST SWITCHED FREQS AND HADN'T BEEN HEARING THE SIMILAR CALL SIGN BEFORE. WE WERE ALSO AT THE END OF AN 11 1/2 HR CREW DAY.

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.