Flight crew descended below assigned altitude prior to fix on approach.

Attributes
ACN	429731
Time
Date	199902
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	intersection : fnuch
State Reference	IL
Altitude	msl bound lower : 6700 msl bound upper : 7000
Environment
Light	Night
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 22r other
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
ASRS Report	429731
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	429730
Events
Anomaly	altitude deviation : undershoot non adherence : clearance non adherence : published procedure
Independent Detector	other controllera other flight crewa other other : 1
Resolutory Action	controller : issued advisory flight crew : returned to original clearance
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ATC facility: ord approach. Location: runway 22R approach. We were cleared to 7000 ft and cleared for the approach to runway 22R. First officer set altitude window for next altitude, which was 5000 ft. The problem was the airplane was still descending in flight level change. We were supposed to be at fnuch at 7000 ft, then descend to the next point. We descended too early before fnuch by only 300 ft then climbed back to 7000 ft. Ord approach called and said we needed to be at 7000 ft until after fnuch. We already were climbing at the time of the call. The rest of the approach was uneventful.

Original NASA ASRS Text

Title: FLC DSNDED BELOW ASSIGNED ALT PRIOR TO FIX ON APCH.

Narrative: ATC FACILITY: ORD APCH. LOCATION: RWY 22R APCH. WE WERE CLRED TO 7000 FT AND CLRED FOR THE APCH TO RWY 22R. FO SET ALT WINDOW FOR NEXT ALT, WHICH WAS 5000 FT. THE PROB WAS THE AIRPLANE WAS STILL DSNDING IN FLT LEVEL CHANGE. WE WERE SUPPOSED TO BE AT FNUCH AT 7000 FT, THEN DSND TO THE NEXT POINT. WE DSNDED TOO EARLY BEFORE FNUCH BY ONLY 300 FT THEN CLBED BACK TO 7000 FT. ORD APCH CALLED AND SAID WE NEEDED TO BE AT 7000 FT UNTIL AFTER FNUCH. WE ALREADY WERE CLBING AT THE TIME OF THE CALL. THE REST OF THE APCH WAS UNEVENTFUL.

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.