FMS steered aircraft some 20-25 mi off course with no warning to flight crew.

Attributes
ACN	79998
Time
Date	198801
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : put airport : bos
State Reference	MA
Altitude	msl bound lower : 28000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zbw
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 17000 flight time type : 1200
ASRS Report	79998
Person 2
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Clrd direct private VOR after takeoff bos. Using right navigation FMS and omega bos center advised we missed private VOR by 20 mi. Upon checking found both FMS and omega in gross error. Advised center of same and requested airways flight plan. Received same. Malfunction recorded in aircraft log for maintenance action.

Original NASA ASRS Text

Title: FMS STEERED ACFT SOME 20-25 MI OFF COURSE WITH NO WARNING TO FLT CREW.

Narrative: CLRD DIRECT PVT VOR AFTER TKOF BOS. USING R NAV FMS AND OMEGA BOS CENTER ADVISED WE MISSED PVT VOR BY 20 MI. UPON CHECKING FOUND BOTH FMS AND OMEGA IN GROSS ERROR. ADVISED CENTER OF SAME AND REQUESTED AIRWAYS FLT PLAN. RECEIVED SAME. MALFUNCTION RECORDED IN ACFT LOG FOR MAINT ACTION.

Data retrieved from NASA's ASRS site as of August 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.