Heading track deviation by an A320 flight crew during a navigation error when the FMS has turned them off course from their flight plan route 35-40 NM west of ocs, wy.

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Attributes
ACN	595697
Time
Date	200310
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : ocs.vortac
State Reference	WY
Altitude	msl single value : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 9000 flight time type : 900
ASRS Report	595697
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance non adherence : company policies non adherence : published procedure other anomaly other other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued advisory flight crew : became reoriented flight crew : returned to intended or assigned course
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Route of flight iad...buffer J158. Sb.J34.01.fsd.ocs.J154.J158.MVA.MOD2.sfo. While loading FMGC, idented J154/J158 intersection as bvl -250/LC4-213. FMGC accepted 'ocs, J154 to this intersection.' (FMGC was installed by captain (PNF). I checked route by using 'stored rtes' function of FMGC and confirmed route was iad. Buffer...ocs.J154.intersection.MVA...sfo. Later in flight we were cleared direct ocs, fpr. About 5 mins west of ocs, slc asked us 'where you going?' a quick check showed ocs-tch-bvl was not in J154, but we were going ocs direct the build intersection. We re-installed the route and continued. (Later we went direct MVA) estimate we were 10-12 NM north of route when queried by center. Fixes: 1) xchk entire route point to point (not just 'stored route'), especially with jet route/jet route flight plan. 2) simpler flight plan (ocs J154 spruz direct MVA) would cause less confusion installing route in FMGC. 3) fix airbus FMGC so it will not install a jet route without proper points included.

Original NASA ASRS Text

Title: HDG TRACK DEV BY AN A320 FLT CREW DURING A NAV ERROR WHEN THE FMS HAS TURNED THEM OFF COURSE FROM THEIR FLT PLAN RTE 35-40 NM W OF OCS, WY.

Narrative: RTE OF FLT IAD...BUFFER J158. SB.J34.01.FSD.OCS.J154.J158.MVA.MOD2.SFO. WHILE LOADING FMGC, IDENTED J154/J158 INTXN AS BVL -250/LC4-213. FMGC ACCEPTED 'OCS, J154 TO THIS INTXN.' (FMGC WAS INSTALLED BY CAPT (PNF). I CHKED RTE BY USING 'STORED RTES' FUNCTION OF FMGC AND CONFIRMED RTE WAS IAD. BUFFER...OCS.J154.INTXN.MVA...SFO. LATER IN FLT WE WERE CLRED DIRECT OCS, FPR. ABOUT 5 MINS W OF OCS, SLC ASKED US 'WHERE YOU GOING?' A QUICK CHK SHOWED OCS-TCH-BVL WAS NOT IN J154, BUT WE WERE GOING OCS DIRECT THE BUILD INTXN. WE RE-INSTALLED THE RTE AND CONTINUED. (LATER WE WENT DIRECT MVA) ESTIMATE WE WERE 10-12 NM N OF RTE WHEN QUERIED BY CTR. FIXES: 1) XCHK ENTIRE RTE POINT TO POINT (NOT JUST 'STORED RTE'), ESPECIALLY WITH JET RTE/JET RTE FLT PLAN. 2) SIMPLER FLT PLAN (OCS J154 SPRUZ DIRECT MVA) WOULD CAUSE LESS CONFUSION INSTALLING RTE IN FMGC. 3) FIX AIRBUS FMGC SO IT WILL NOT INSTALL A JET RTE WITHOUT PROPER POINTS INCLUDED.

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.