Flight crew of A320 descended below cleared altitude on descent to dtw when approach controls fails ...

Attributes
ACN	601287
Time
Date	200312
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : scubi
State Reference	MI
Altitude	msl bound lower : 10000 msl bound upper : 11000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d21.tracon
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude descent : holding descent : approach
Route In Use	arrival star : polar
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 2000
ASRS Report	601287
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : returned to assigned altitude
Supplementary
Problem Areas	Environmental Factor Flight Crew Human Performance Airport ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On arrival to dtw, we were delayed. Initially we were issued holding at giber on the polar 1 arrival. ATC decided to hold us closer to dtw so they canceled the giber hold and had us continue on the arrival. We slowed and continued on the arrival and were issued holding at polar intersection on the arrival. We held for 20+ mins and were cleared to continue with the arrival. Controller had assigned a heading, passing scubi intersection, to 150 degrees. Approaching scubi, the controller issued a descent clearance to 10000 ft. I read back 10000 ft and set that altitude in the MCP. Both pilots complied with the SOP by pointing at the new altitude and the PF repeated the assigned altitude. Approaching 10200 ft, the controller indicated we were only cleared to 11000 ft and told us to climb immediately back to 11000 ft. I am certain he previously issued 10000 ft. Controller did not indicate there was any conflict. Min or 2 later, controller issued frequency change to 125.95, which was read back. The frequency was in error. Went back to the issuing controller and he said he gave us 125.15. After our previous experience we were listening very close and the controller initially issued 125.95. Captain did call dispatch and reported the altitude deviation. Controller hearback was not occurring effectively. The visibility was good but the wind was out of the west gusting to 38 KTS which was affecting airport operations. After the error on my first report attempt, I realize that I was more fatigued than I realized.

Original NASA ASRS Text

Title: FLT CREW OF A320 DSNDED BELOW CLRED ALT ON DSCNT TO DTW WHEN APCH CTLS FAILS TO RECOGNIZE THEY READ BACK 10000 FT INSTEAD OF 11000 FT.

Narrative: ON ARR TO DTW, WE WERE DELAYED. INITIALLY WE WERE ISSUED HOLDING AT GIBER ON THE POLAR 1 ARR. ATC DECIDED TO HOLD US CLOSER TO DTW SO THEY CANCELED THE GIBER HOLD AND HAD US CONTINUE ON THE ARR. WE SLOWED AND CONTINUED ON THE ARR AND WERE ISSUED HOLDING AT POLAR INTXN ON THE ARR. WE HELD FOR 20+ MINS AND WERE CLRED TO CONTINUE WITH THE ARR. CTLR HAD ASSIGNED A HDG, PASSING SCUBI INTXN, TO 150 DEGS. APCHING SCUBI, THE CTLR ISSUED A DSCNT CLRNC TO 10000 FT. I READ BACK 10000 FT AND SET THAT ALT IN THE MCP. BOTH PLTS COMPLIED WITH THE SOP BY POINTING AT THE NEW ALT AND THE PF REPEATED THE ASSIGNED ALT. APCHING 10200 FT, THE CTLR INDICATED WE WERE ONLY CLRED TO 11000 FT AND TOLD US TO CLB IMMEDIATELY BACK TO 11000 FT. I AM CERTAIN HE PREVIOUSLY ISSUED 10000 FT. CTLR DID NOT INDICATE THERE WAS ANY CONFLICT. MIN OR 2 LATER, CTLR ISSUED FREQ CHANGE TO 125.95, WHICH WAS READ BACK. THE FREQ WAS IN ERROR. WENT BACK TO THE ISSUING CTLR AND HE SAID HE GAVE US 125.15. AFTER OUR PREVIOUS EXPERIENCE WE WERE LISTENING VERY CLOSE AND THE CTLR INITIALLY ISSUED 125.95. CAPT DID CALL DISPATCH AND RPTED THE ALTDEV. CTLR HEARBACK WAS NOT OCCURRING EFFECTIVELY. THE VISIBILITY WAS GOOD BUT THE WIND WAS OUT OF THE W GUSTING TO 38 KTS WHICH WAS AFFECTING ARPT OPS. AFTER THE ERROR ON MY FIRST RPT ATTEMPT, I REALIZE THAT I WAS MORE FATIGUED THAN I REALIZED.

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.

Flight crew of A320 descended below cleared altitude on descent to dtw when approach controls fails to recognize they read back 10000 ft instead of 11000 ft.