FK10 crew confused similar call signs and descended in ZKC class a airspace.

Attributes
ACN	472920
Time
Date	200005
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : loamy
State Reference	MO
Altitude	msl bound lower : 32200 msl bound upper : 33000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc.artcc
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zkc.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
ASRS Report	472920
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : company policies non adherence : published procedure
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned altitude none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Altitude deviation. Center cleared us to FL240. We were not sure of the call sign. It sounded like wxyz, but we read the clearance back. 800 ft in our descent, when we heard another call for wxyz, we realized the error and returned to our original altitude of FL330. We missed the call thinking it was for xyz and the controller missed our readback.

Original NASA ASRS Text

Title: FK10 CREW CONFUSED SIMILAR CALL SIGNS AND DSNDED IN ZKC CLASS A AIRSPACE.

Narrative: ALTDEV. CTR CLRED US TO FL240. WE WERE NOT SURE OF THE CALL SIGN. IT SOUNDED LIKE WXYZ, BUT WE READ THE CLRNC BACK. 800 FT IN OUR DSCNT, WHEN WE HEARD ANOTHER CALL FOR WXYZ, WE REALIZED THE ERROR AND RETURNED TO OUR ORIGINAL ALT OF FL330. WE MISSED THE CALL THINKING IT WAS FOR XYZ AND THE CTLR MISSED OUR READBACK.

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.