A B-747-250 may have been off course at trevr.

Attributes
ACN	269411
Time
Date	199404
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : eni
State Reference	CA
Altitude	msl bound lower : 41000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
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
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 : 180 flight time total : 20000 flight time type : 7000
ASRS Report	269411
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 11850 flight time type : 1500
ASRS Report	269400
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

Approximately 40 mi prior to trevr, ZOA called us. We answered. Gave us a code to squawk, gave us radar contact. We requested direct ave. Oak gave us direct ave approximately 22 mi northwest of trevr. Made left turn of 15 degrees to go direct. ATC called a couple of mins later to say they were filing an equipment report because we missed trevr by more than 20 mi. We weren't going to trevr but that didn't matter to ATC. INS error on arrival at lax was #1 -- 18 mi, #2 -- 17 mi, and #3 -- 17 mi, all within company tolerances. Asked ATC to keep receive/transmit tapes because of this apparent mis-communication. Supplemental information from acn 269400: ZOA said we were 25 mi north of trevr, after we turned 15 degrees left and were proceeding to ave. Our INS showed us 25 mi northwest of trevr, so we concurred. ZOA said they were filing a gross navigation error on us, saying we were 25 mi off course. Our INS and navigation charts indicated we were on course the entire flight. My impression is that this was a communication error between the 2 controllers at ZOA. We were approximately 25 mi from trevr when we were cleared direct ave. We turned left, and looked as if we turned further 'off-course.'

Original NASA ASRS Text

Title: A B-747-250 MAY HAVE BEEN OFF COURSE AT TREVR.

Narrative: APPROX 40 MI PRIOR TO TREVR, ZOA CALLED US. WE ANSWERED. GAVE US A CODE TO SQUAWK, GAVE US RADAR CONTACT. WE REQUESTED DIRECT AVE. OAK GAVE US DIRECT AVE APPROX 22 MI NW OF TREVR. MADE L TURN OF 15 DEGS TO GO DIRECT. ATC CALLED A COUPLE OF MINS LATER TO SAY THEY WERE FILING AN EQUIP RPT BECAUSE WE MISSED TREVR BY MORE THAN 20 MI. WE WEREN'T GOING TO TREVR BUT THAT DIDN'T MATTER TO ATC. INS ERROR ON ARR AT LAX WAS #1 -- 18 MI, #2 -- 17 MI, AND #3 -- 17 MI, ALL WITHIN COMPANY TOLERANCES. ASKED ATC TO KEEP RECEIVE/XMIT TAPES BECAUSE OF THIS APPARENT MIS-COM. SUPPLEMENTAL INFO FROM ACN 269400: ZOA SAID WE WERE 25 MI N OF TREVR, AFTER WE TURNED 15 DEGS L AND WERE PROCEEDING TO AVE. OUR INS SHOWED US 25 MI NW OF TREVR, SO WE CONCURRED. ZOA SAID THEY WERE FILING A GROSS NAV ERROR ON US, SAYING WE WERE 25 MI OFF COURSE. OUR INS AND NAV CHARTS INDICATED WE WERE ON COURSE THE ENTIRE FLT. MY IMPRESSION IS THAT THIS WAS A COM ERROR BTWN THE 2 CTLRS AT ZOA. WE WERE APPROX 25 MI FROM TREVR WHEN WE WERE CLRED DIRECT AVE. WE TURNED L, AND LOOKED AS IF WE TURNED FURTHER 'OFF-COURSE.'

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.