A B737 flight crew descended to an altitude not depicted on the assigned STAR at dfw.

Attributes
ACN	441010
Time
Date	199906
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : cqy.vortac
State Reference	TX
Altitude	msl single value : 10000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : d10.tracon
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Route In Use	arrival star : cqy4
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 pilot : cfi
Experience	flight time last 90 days : 170 flight time total : 10410 flight time type : 3500
ASRS Report	441010
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 : published procedure non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued advisory
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were outbound on the cqy 309 degree radial. ATC instructed us to cross tacke intersection at 11000 ft, delete the 250 KT speed restr and to cross dietz intersection at 210 KTS. Somehow we thought we heard to cross dietz at 10000 ft and 210 KTS. I put 10000 ft and 210 KTS into the FMC and the MCP. The captain and myself confirmed the 10000 ft, but did not question it. The airplane descended as programmed. At dietz we turned to the published heading of 350 degrees. After dietz, ATC instructed us to descend to 7000 ft. During the descent ATC asked us how long we had been at 10000 ft. We replied 1 min or 2.

Original NASA ASRS Text

Title: A B737 FLC DSNDED TO AN ALT NOT DEPICTED ON THE ASSIGNED STAR AT DFW.

Narrative: WE WERE OUTBOUND ON THE CQY 309 DEG RADIAL. ATC INSTRUCTED US TO CROSS TACKE INTXN AT 11000 FT, DELETE THE 250 KT SPD RESTR AND TO CROSS DIETZ INTXN AT 210 KTS. SOMEHOW WE THOUGHT WE HEARD TO CROSS DIETZ AT 10000 FT AND 210 KTS. I PUT 10000 FT AND 210 KTS INTO THE FMC AND THE MCP. THE CAPT AND MYSELF CONFIRMED THE 10000 FT, BUT DID NOT QUESTION IT. THE AIRPLANE DSNDED AS PROGRAMMED. AT DIETZ WE TURNED TO THE PUBLISHED HDG OF 350 DEGS. AFTER DIETZ, ATC INSTRUCTED US TO DSND TO 7000 FT. DURING THE DSCNT ATC ASKED US HOW LONG WE HAD BEEN AT 10000 FT. WE REPLIED 1 MIN OR 2.

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.