An air carrier widebody transport freighter captain reports that he had an altitude deviation.

Attributes
ACN	356770
Time
Date	199612
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bwz
State Reference	NJ
Altitude	msl bound lower : 17000 msl bound upper : 17220
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 60 flight time total : 8000 flight time type : 120
ASRS Report	356770
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Climbing out of ewr en route to parke intersection, we were told to level at 17000 ft by new york. We had been discussing flight director and CADC problems throughout the climb when we were given the clearance. Upon leveling at 17000 ft, the captain's altimeter read 17100 ft and the first officer's read 17000 ft, and the flight director was still showing a climb above the 20 degree pitch mark on the pfd. The aircraft was corrected at 17220 ft and descended to 17000 ft, at which time the flight director rapidly jumped down to show a level attitude. Several times throughout the trip we would ask ATC what they were showing our altitude at, and each time the captain's altimeter was 60-100 ft off. Compared to the first officer's altimeter, the difference was the same. Arriving at our destination, both problems, the flight director and the altitude problems were written in the aircraft maintenance log.

Original NASA ASRS Text

Title: AN ACR WDB FREIGHTER CAPT RPTS THAT HE HAD AN ALTDEV.

Narrative: CLBING OUT OF EWR ENRTE TO PARKE INTXN, WE WERE TOLD TO LEVEL AT 17000 FT BY NEW YORK. WE HAD BEEN DISCUSSING FLT DIRECTOR AND CADC PROBS THROUGHOUT THE CLB WHEN WE WERE GIVEN THE CLRNC. UPON LEVELING AT 17000 FT, THE CAPT'S ALTIMETER READ 17100 FT AND THE FO'S READ 17000 FT, AND THE FLT DIRECTOR WAS STILL SHOWING A CLB ABOVE THE 20 DEG PITCH MARK ON THE PFD. THE ACFT WAS CORRECTED AT 17220 FT AND DSNDED TO 17000 FT, AT WHICH TIME THE FLT DIRECTOR RAPIDLY JUMPED DOWN TO SHOW A LEVEL ATTITUDE. SEVERAL TIMES THROUGHOUT THE TRIP WE WOULD ASK ATC WHAT THEY WERE SHOWING OUR ALT AT, AND EACH TIME THE CAPT'S ALTIMETER WAS 60-100 FT OFF. COMPARED TO THE FO'S ALTIMETER, THE DIFFERENCE WAS THE SAME. ARRIVING AT OUR DEST, BOTH PROBS, THE FLT DIRECTOR AND THE ALT PROBS WERE WRITTEN IN THE ACFT MAINT LOG.

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.