Flight crew on downwind vectors accept a clearance intended for another air carrier flight.

Attributes
ACN	141178
Time
Date	199004
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 6000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other cruise other descent : approach
Route In Use	arrival other enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12000 flight time type : 10000
ASRS Report	141178
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other other : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation Operational Deviation other
Situations
ATC Facility	other physical facility

Narrative:

We were level 6000', heading 320 degree on a left downwind to runway 14R at ord, IMC, both left and right runways in use. Controller starting to give callsigns before keying microphone. A number of other aircraft had to confirm whether or not a specific clearance was for them. We accepted a clearance to 'turn left to 150 degree, maintain 4000' until established, cleared for the approach'. Although we thought a 170 degree turn on as unusual, we were 12 mi from the field, would be going through the runway 14L approach path and this is O'hare. We did read back the entire clearance with full callsign. We were 90 degrees into the turn and had descended from 6000' to 5000' when another aircraft told the controller that 'someone else took our clearance'. The controller immediately gave us a turn back to 320 degrees and told us to level at 5000'. No other evasive action taken. Unusual approach confign to ord. 'Normal' ord traffic, busy and fast talking. Controller clipping callsigns. Controller not confirming read backs.

Original NASA ASRS Text

Title: FLT CREW ON DOWNWIND VECTORS ACCEPT A CLRNC INTENDED FOR ANOTHER ACR FLT.

Narrative: WE WERE LEVEL 6000', HDG 320 DEG ON A L DOWNWIND TO RWY 14R AT ORD, IMC, BOTH L AND R RWYS IN USE. CTLR STARTING TO GIVE CALLSIGNS BEFORE KEYING MIKE. A NUMBER OF OTHER ACFT HAD TO CONFIRM WHETHER OR NOT A SPECIFIC CLRNC WAS FOR THEM. WE ACCEPTED A CLRNC TO 'TURN L TO 150 DEG, MAINTAIN 4000' UNTIL ESTABLISHED, CLRED FOR THE APCH'. ALTHOUGH WE THOUGHT A 170 DEG TURN ON AS UNUSUAL, WE WERE 12 MI FROM THE FIELD, WOULD BE GOING THROUGH THE RWY 14L APCH PATH AND THIS IS O'HARE. WE DID READ BACK THE ENTIRE CLRNC WITH FULL CALLSIGN. WE WERE 90 DEGS INTO THE TURN AND HAD DSNDED FROM 6000' TO 5000' WHEN ANOTHER ACFT TOLD THE CTLR THAT 'SOMEONE ELSE TOOK OUR CLRNC'. THE CTLR IMMEDIATELY GAVE US A TURN BACK TO 320 DEGS AND TOLD US TO LEVEL AT 5000'. NO OTHER EVASIVE ACTION TAKEN. UNUSUAL APCH CONFIGN TO ORD. 'NORMAL' ORD TFC, BUSY AND FAST TALKING. CTLR CLIPPING CALLSIGNS. CTLR NOT CONFIRMING READ BACKS.

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.