B777 crew had altitude undershoot in C90 class B.

Attributes
ACN	489500
Time
Date	200010
Day	Sun
Local Time Of Day	1801 To 2400
Place
State Reference	IL
Altitude	msl bound lower : 4000 msl bound upper : 5000
Environment
Light	Night
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other
Flight Phase	climbout : vacating altitude
Route In Use	departure : on vectors departure sid : ns
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	489500
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
ASRS Report	489501
Events
Anomaly	altitude deviation : undershoot non adherence : clearance non adherence : company policies non adherence : far non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Departure clearance conflict. As PF I was climbing rapidly through 3000 ft when first officer called 3 for 4. Glanced at MCP and saw 4000 ft in altitude window. Leveled at 4000 ft. Shortly afterwards departure asked our altitude and said we were supposed to be at 5000 ft. Had 2 1/2 hour departure delay on ramp. 5000 ft was clearance and briefed. Neither first officer nor I know how 4000 ft got into altitude window, but things were happening rapidly and I had to level. Departure questioned us before we could question unusual departure altitude for ord.

Original NASA ASRS Text

Title: B777 CREW HAD ALT UNDERSHOOT IN C90 CLASS B.

Narrative: DEP CLRNC CONFLICT. AS PF I WAS CLBING RAPIDLY THROUGH 3000 FT WHEN FO CALLED 3 FOR 4. GLANCED AT MCP AND SAW 4000 FT IN ALT WINDOW. LEVELED AT 4000 FT. SHORTLY AFTERWARDS DEP ASKED OUR ALT AND SAID WE WERE SUPPOSED TO BE AT 5000 FT. HAD 2 1/2 HR DEP DELAY ON RAMP. 5000 FT WAS CLRNC AND BRIEFED. NEITHER FO NOR I KNOW HOW 4000 FT GOT INTO ALT WINDOW, BUT THINGS WERE HAPPENING RAPIDLY AND I HAD TO LEVEL. DEP QUESTIONED US BEFORE WE COULD QUESTION UNUSUAL DEP ALT FOR ORD.

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.