A B737-300 FLC DEPARTING ON THE IDALE RNAV 1 DEP HAS 2 RNAV FIXES DROP OUT OF THE SYS CAUSING THE ACFT TO TURN IN THE WRONG DIRECTION.

Narrative

DEPARTING LAS ON 'IDALE RNAV 1 DEP;' AFTER 'LODZY;' ATC CTLR CLRED US DIRECT TO IDALE INTXN. AT IDALE INTXN; THE ACFT STARTED A SHARP R TURN. THE NEXT 2 FIXES HAD DROPPED OUT OF THE FMC COMPUTER (SHEAD AND BIKKR) AND THE ACFT WAS PROCEEDING TO OAL. WE WERE ASKED BY LAS DEP WHAT HDG WE WERE TURNING TO OVER IDALE. THE CTLR SAID THAT RECENTLY A LOT OF AIRPLANES WERE TURNING TOO FAR R AT IDALE. HE SAID TO TURN TO A HDG OF 250 DEGS; WHICH WE DID; AND PROCEEDED WITH THE FLT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HIS COMPANY OPERATES THE SAME TYPE ACFT WITH DIFFERENT NAV EQUIP CONFIGNS. DURING THE DEP STATED IN THIS ACN; THE ACFT WAS EQUIPPED WITH A SINGLE FMC AND NO CRT NAV DISPLAY. THE FMC IS LOCATED ON THE CAPT'S SIDE OF THE CONSOLE AND THE PNF (FO) HAD LIMITED VISUAL ACCESS TO THE EQUIP. WHEN DEP CTL ISSUED A CLRNC TO 'GO DIRECT' AND THE COMMAND WAS INPUT; THE PNF DID NOT OBSERVE THE NEXT 2 FIXES DROP OUT OF THE SYS DUE TO THE LOCATION OF THE FMC. UPON REACHING THE 'DIRECT TO FIX' THE ACFT TURNED THE WRONG DIRECTION.