Deviation from clearance - air carrier on a pacific route is off course as it approachs coast.

Attributes
ACN	298728
Time
Date	199503
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ent
State Reference	CA
Altitude	msl bound lower : 39000 msl bound upper : 39000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa tower : atl
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : other oceanic enroute : pacific enroute airway : zoa
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time total : 8000
ASRS Report	298728
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 25000 flight time type : 3500
ASRS Report	299109
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	aircraft : equipment problem dissipated flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Oakland radar (ATC) reported our position 20 mi short (west) and 5 mi right (south) of course, we showed over trevor. We used normal navigation procedures - INS system in triple mix. At the gate in lax INS radial errors for INS's were as follows #1 - .7 NM #2, 2.4 NM and #3, 2.2 NM - all within limits for navigation deviation - flight was slightly less than 10 hours. Supplemental information from acn 299109: used normal airline navigation procedures - INS triple mix. ZOA reported us off course at trevor. At gate at lax #1 INS radial error equal .7 mi, #2 INS radial error equal 2.4 mi, #3 INS radial error equal 2.2 mi, all within limits per hour. Flight was slightly less than 10 hours duration.

Original NASA ASRS Text

Title: DEV FROM CLRNC - ACR ON A PACIFIC RTE IS OFF COURSE AS IT APCHS COAST.

Narrative: OAKLAND RADAR (ATC) RPTED OUR POS 20 MI SHORT (W) AND 5 MI R (S) OF COURSE, WE SHOWED OVER TREVOR. WE USED NORMAL NAV PROCS - INS SYS IN TRIPLE MIX. AT THE GATE IN LAX INS RADIAL ERRORS FOR INS'S WERE AS FOLLOWS #1 - .7 NM #2, 2.4 NM AND #3, 2.2 NM - ALL WITHIN LIMITS FOR NAV DEV - FLT WAS SLIGHTLY LESS THAN 10 HRS. SUPPLEMENTAL INFO FROM ACN 299109: USED NORMAL AIRLINE NAV PROCS - INS TRIPLE MIX. ZOA RPTED US OFF COURSE AT TREVOR. AT GATE AT LAX #1 INS RADIAL ERROR EQUAL .7 MI, #2 INS RADIAL ERROR EQUAL 2.4 MI, #3 INS RADIAL ERROR EQUAL 2.2 MI, ALL WITHIN LIMITS PER HR. FLT WAS SLIGHTLY LESS THAN 10 HRS DURATION.

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.