Aircraft deviated from assigned departure route, due to FMS error.

Attributes
ACN	296144
Time
Date	199502
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : slc
State Reference	UT
Altitude	msl bound lower : 21000 msl bound upper : 21000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
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
Route In Use	departure other departure sid : sid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 150 flight time total : 10000 flight time type : 1500
ASRS Report	296144
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Depart slc, runway 34, flying the milford 1 departure, milford transition. After becoming airborne, we were vectored 280 degree and then 170 degrees to join the milford 1 departure. Passing FL210, ZLC asked why we had not joined. Our 170 degree heading had us paralleling the route. ZLC informed us our FMS route was in error. Upon further investigation we concurred. Moral of the situation, always back up FMS departure/arrival with VOR bearings and distance.

Original NASA ASRS Text

Title: ACFT DEVIATED FROM ASSIGNED DEP RTE, DUE TO FMS ERROR.

Narrative: DEPART SLC, RWY 34, FLYING THE MILFORD 1 DEP, MILFORD TRANSITION. AFTER BECOMING AIRBORNE, WE WERE VECTORED 280 DEG AND THEN 170 DEGS TO JOIN THE MILFORD 1 DEP. PASSING FL210, ZLC ASKED WHY WE HAD NOT JOINED. OUR 170 DEG HDG HAD US PARALLELING THE RTE. ZLC INFORMED US OUR FMS RTE WAS IN ERROR. UPON FURTHER INVESTIGATION WE CONCURRED. MORAL OF THE SIT, ALWAYS BACK UP FMS DEP/ARR WITH VOR BEARINGS AND DISTANCE.

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.