Flight crew levels off at altitude different than intended by ATC.

Attributes
ACN	314400
Time
Date	199508
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gve airport : iad
State Reference	VA
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad
Operator	general aviation : corporate
Make Model Name	Super King Air 200 HDC
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	departure other departure sid : sid enroute other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 4000
ASRS Report	314400
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 8900 flight time type : 4500
ASRS Report	314408
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Departed iad on the capitol 4 departure and subsequently cleared to 9000 ft. I set 9000 ft in the altitude alerter and climbed to our assigned altitude. After we were level for approximately 5 mins departure control requested our altitude. I replied level at 9000 ft, the controller said that we were only cleared 8000 ft but not to worry about it and he would inform center that we were level at 9000 ft. I did not question the controller before switching to center about this mix-up, but I believe we were cleared to 9000 ft because no one questioned the readback. However, it is possible that I could have read back 8000 ft and set in 9000 ft in the alerter and no one saw it. I would like to know because it has never happened to me before.

Original NASA ASRS Text

Title: FLC LEVELS OFF AT ALT DIFFERENT THAN INTENDED BY ATC.

Narrative: DEPARTED IAD ON THE CAPITOL 4 DEP AND SUBSEQUENTLY CLRED TO 9000 FT. I SET 9000 FT IN THE ALT ALERTER AND CLBED TO OUR ASSIGNED ALT. AFTER WE WERE LEVEL FOR APPROX 5 MINS DEP CTL REQUESTED OUR ALT. I REPLIED LEVEL AT 9000 FT, THE CTLR SAID THAT WE WERE ONLY CLRED 8000 FT BUT NOT TO WORRY ABOUT IT AND HE WOULD INFORM CTR THAT WE WERE LEVEL AT 9000 FT. I DID NOT QUESTION THE CTLR BEFORE SWITCHING TO CTR ABOUT THIS MIX-UP, BUT I BELIEVE WE WERE CLRED TO 9000 FT BECAUSE NO ONE QUESTIONED THE READBACK. HOWEVER, IT IS POSSIBLE THAT I COULD HAVE READ BACK 8000 FT AND SET IN 9000 FT IN THE ALERTER AND NO ONE SAW IT. I WOULD LIKE TO KNOW BECAUSE IT HAS NEVER HAPPENED TO ME BEFORE.

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.