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.'