B737-200 crew had a track deviation in ZNY class a airspace.

Attributes
ACN	511810
Time
Date	200105
Day	Fri
Place
Locale Reference	atc facility : zny.artcc
State Reference	NY
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-200
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : flight engineer
Experience	flight time last 90 days : 100 flight time total : 10500 flight time type : 400
ASRS Report	511810
Events
Anomaly	aircraft equipment problem : critical non adherence : clearance other anomaly other other spatial deviation
Resolutory Action	controller : issued alert flight crew : returned to intended or assigned course
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

First officer's (PF's) artificial horizon precessed slightly, but not enough to illuminate the instrument comparator. This caused the autoplt to slowly turn the aircraft to the left. ATC notified us that we were heading off course, and we corrected. To our knowledge, no aircraft conflict occurred. It is important to note that this occurred during a period of time when the captain had left the flight deck, had just returned and the first officer was removing his oxygen mask. These distrs may have contributed to the crew not noticing the heading error.

Original NASA ASRS Text

Title: B737-200 CREW HAD A TRACK DEV IN ZNY CLASS A AIRSPACE.

Narrative: FO'S (PF'S) ARTIFICIAL HORIZON PRECESSED SLIGHTLY, BUT NOT ENOUGH TO ILLUMINATE THE INST COMPARATOR. THIS CAUSED THE AUTOPLT TO SLOWLY TURN THE ACFT TO THE L. ATC NOTIFIED US THAT WE WERE HDG OFF COURSE, AND WE CORRECTED. TO OUR KNOWLEDGE, NO ACFT CONFLICT OCCURRED. IT IS IMPORTANT TO NOTE THAT THIS OCCURRED DURING A PERIOD OF TIME WHEN THE CAPT HAD LEFT THE FLT DECK, HAD JUST RETURNED AND THE FO WAS REMOVING HIS OXYGEN MASK. THESE DISTRS MAY HAVE CONTRIBUTED TO THE CREW NOT NOTICING THE HDG ERROR.

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.