Air carrier crew and controller disagree on what approach assignment is.

Attributes
ACN	449400
Time
Date	199909
Day	Mon
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : dtw.airport
State Reference	MI
Altitude	msl single value : 3000
Environment
Flight Conditions	VMC
Light	Dawn
Aircraft 1
Controlling Facilities	tracon : d21.tracon tower : dtw.tower
Operator	common carrier : air carrier
Make Model Name	Light Transport
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 21l
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 150 flight time total : 3000 flight time type : 2000
ASRS Report	449400
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance

Narrative:

We were inbound to dtw, where we were told to expect the ILS for runway 21L. There had been NOTAMS that runway 21R and runway 21C were closed. The controller cleared us for an approach. We thought he cleared us for runway 21L. He says he cleared us for runway 21R. When we were established on the localizer for runway 21L he told us he had cleared us for runway 21R. We are not sure who is right. But the controller should have advised us of the change of approach. No conflict of traffic resulted from this even though we crossed the approach for runway 21R to get to runway 21L.

Original NASA ASRS Text

Title: ACR CREW AND CTLR DISAGREE ON WHAT APCH ASSIGNMENT IS.

Narrative: WE WERE INBOUND TO DTW, WHERE WE WERE TOLD TO EXPECT THE ILS FOR RWY 21L. THERE HAD BEEN NOTAMS THAT RWY 21R AND RWY 21C WERE CLOSED. THE CTLR CLRED US FOR AN APCH. WE THOUGHT HE CLRED US FOR RWY 21L. HE SAYS HE CLRED US FOR RWY 21R. WHEN WE WERE ESTABLISHED ON THE LOC FOR RWY 21L HE TOLD US HE HAD CLRED US FOR RWY 21R. WE ARE NOT SURE WHO IS RIGHT. BUT THE CTLR SHOULD HAVE ADVISED US OF THE CHANGE OF APCH. NO CONFLICT OF TFC RESULTED FROM THIS EVEN THOUGH WE CROSSED THE APCH FOR RWY 21R TO GET TO RWY 21L.

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.