Flight crew hears and reads back clearance and executes clearance intended for another aircraft.

Attributes
ACN	547396
Time
Date	200205
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl single value : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : multi engine pilot : atp
Experience	flight time last 90 days : 100 flight time total : 3750 flight time type : 350
ASRS Report	54
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : private pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9000 flight time type : 500
ASRS Report	547403
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory controller : issued new clearance flight crew : returned to assigned altitude flight crew : returned to intended or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While level at 10000 MSL, 300 KTS, PNF and PF both heard chicago approach say 'XXX, turn left 090 degrees, slow to 250 KTS, when speed is good, descend to 3000 ft.' PNF read back clearance exactly as given including call sign. Aircraft was turned to 090 degrees and slowed to 250 KTS, then a descent was started to 3000 ft. Passing 9500 ft, approach controller queried us about our altitude. We stated XXX was passing 9500 ft for 3000 ft. Chicago approach stated that clearance was not for us and that he was sorry he didn't catch the readback. Approach told us to level at 9000 ft. New vectors were given and arrival into ord was uneventful. Both PNF and PF are fairly certain the clearance was given to air carrier XXX. There was an air carrier yxx airborne at the time, but we could not tell if that caused the confusion.

Original NASA ASRS Text

Title: FLC HEARS AND READS BACK CLRNC AND EXECUTES CLRNC INTENDED FOR ANOTHER ACFT.

Narrative: WHILE LEVEL AT 10000 MSL, 300 KTS, PNF AND PF BOTH HEARD CHICAGO APCH SAY 'XXX, TURN L 090 DEGS, SLOW TO 250 KTS, WHEN SPD IS GOOD, DSND TO 3000 FT.' PNF READ BACK CLRNC EXACTLY AS GIVEN INCLUDING CALL SIGN. ACFT WAS TURNED TO 090 DEGS AND SLOWED TO 250 KTS, THEN A DSCNT WAS STARTED TO 3000 FT. PASSING 9500 FT, APCH CTLR QUERIED US ABOUT OUR ALT. WE STATED XXX WAS PASSING 9500 FT FOR 3000 FT. CHICAGO APCH STATED THAT CLRNC WAS NOT FOR US AND THAT HE WAS SORRY HE DIDN'T CATCH THE READBACK. APCH TOLD US TO LEVEL AT 9000 FT. NEW VECTORS WERE GIVEN AND ARR INTO ORD WAS UNEVENTFUL. BOTH PNF AND PF ARE FAIRLY CERTAIN THE CLRNC WAS GIVEN TO ACR XXX. THERE WAS AN ACR YXX AIRBORNE AT THE TIME, BUT WE COULD NOT TELL IF THAT CAUSED THE CONFUSION.

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.