A B757-200 pilot reports tracking an FMS course on the cri 223 degree radial; but when questioned by ny TRACON; crew discovered an 8 degree heading error from raw data.

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Attributes
ACN	674463
Time
Date	200510
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : jfk.airport
State Reference	NY
Altitude	msl single value : 3000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : n90.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : approach
Route In Use	approach : instrument non precision arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : instrument pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 17000 flight time type : 3500
ASRS Report	674463
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe non adherence : far non adherence : clearance other anomaly other other spatial deviation
Resolutory Action	controller : issued advisory flight crew : overcame equipment problem
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Aircraft Navigational Facility
Primary Problem	Aircraft

Narrative:

Clear night with excellent visibility. Cleared for VOR 13L at jfk via vectored heading to intercept 223 degree heading off canarsie (cri) VOR. LNAV intercept course but ATC questioned if we were on 223 degree radial cri. As just reaching initial approach fix; had yet to place one VOR/ehsi on raw data. We did so and found approximately 8 degrees north of cri 223 degree radial. Corrected via raw data and flew remainder of approach totally raw data. Once on ground; ATC requested we call ny jfk approach. Doing so; constructive chat with subject as to our database/FMS; etc. Seems similar problems encountered on same approach with other airlines and aircraft. Figured our deviation and one mile at maximum point. FAA had 'route checked' approach previously and it checked normal. Callback conversation with reporter revealed the following information: reporter did not know of any changes in the ny area navaids. However; after talking with the TRACON supervisor; questioned the source of the error. He suggested talking with other acrs in the area to compare between GPS equipped aircraft; FMS; and aircraft flying pure raw data. The fact that this had been route checked makes the aircraft suspect.

Original NASA ASRS Text

Title: A B757-200 PLT RPTS TRACKING AN FMS COURSE ON THE CRI 223 DEG RADIAL; BUT WHEN QUESTIONED BY NY TRACON; CREW DISCOVERED AN 8 DEG HDG ERROR FROM RAW DATA.

Narrative: CLR NIGHT WITH EXCELLENT VISIBILITY. CLRED FOR VOR 13L AT JFK VIA VECTORED HDG TO INTERCEPT 223 DEG HDG OFF CANARSIE (CRI) VOR. LNAV INTERCEPT COURSE BUT ATC QUESTIONED IF WE WERE ON 223 DEG RADIAL CRI. AS JUST REACHING INITIAL APCH FIX; HAD YET TO PLACE ONE VOR/EHSI ON RAW DATA. WE DID SO AND FOUND APPROX 8 DEGS N OF CRI 223 DEG RADIAL. CORRECTED VIA RAW DATA AND FLEW REMAINDER OF APCH TOTALLY RAW DATA. ONCE ON GND; ATC REQUESTED WE CALL NY JFK APCH. DOING SO; CONSTRUCTIVE CHAT WITH SUBJECT AS TO OUR DATABASE/FMS; ETC. SEEMS SIMILAR PROBS ENCOUNTERED ON SAME APCH WITH OTHER AIRLINES AND ACFT. FIGURED OUR DEV AND ONE MILE AT MAX POINT. FAA HAD 'RTE CHKED' APCH PREVIOUSLY AND IT CHKED NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR DID NOT KNOW OF ANY CHANGES IN THE NY AREA NAVAIDS. HOWEVER; AFTER TALKING WITH THE TRACON SUPVR; QUESTIONED THE SOURCE OF THE ERROR. HE SUGGESTED TALKING WITH OTHER ACRS IN THE AREA TO COMPARE BETWEEN GPS EQUIPPED ACFT; FMS; AND ACFT FLYING PURE RAW DATA. THE FACT THAT THIS HAD BEEN RTE CHKED MAKES THE ACFT SUSPECT.

Data retrieved from NASA's ASRS site as of January 2009 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.