FLT CREW OF CPR MDT HAD PROBLEM WITH COURSE CAPTURE OF FMC DURING PRODUCTION TEST FLT. MANUFACTURER SAID THIS WAS THE FOURTH OCCURRENCE USING THIS PARTICULAR PROGRAM.

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3/88; I WAS CLRED IN A BLOCK ALT OF FL390 TO 410 AND WAS FLYING AT 40000'. THE ROUTING WAS MULTIPLE CIRCUITS FROM LIT-ARG-RZC-LIT; ETC. APCHING RZC ABOUT 30 NM E; CENTER CLRED ME DIRECT LTT. AT THE TIME I WAS COUPLED TO THE SPERRY FMC AND PROGRAMMED A DIRECT TO LIT FUNCTION. THE AIRPLANE STARTED ITS TURN; AT ABOUT A 150 DEG LEFT TURN; AND I THEN GOT BUSY WITH MY HEAD IN THE COCKPIT SENDING AN EFIS MESSAGE. MY FIRST REALIZATION OF ANYTHING WRONG WAS WHEN CENTER CALLED WITH; 'I THOUGHT YOU WERE GOING DIRECT TO LITTLE ROCK.' AT THE TIME; I WAS HDG NORTHERLY AT 40000' AND EXPLAINED TO CENTER WHAT HAD HAPPENED AND ASKED FOR ANOTHER 360 DEG TURN TO SEE WHAT THE FMC WOULD DO WHEN COUPLED TO THE RIGHT SIDE FLT DIRECTOR. THE REQUEST WAS GRANTED AND THE AIRPLANE DID INDEED NOT CAPTURE THE 'DIRECT TO' LEG ON THE RIGHT FLT DIRECTOR. AFTER THE FLT; THE FMC VENDOR REP INFORMED ME THAT THIS WAS THE FOURTH OCCURRENCE KNOWN WITH THE NEW SOFTWARE PROGRAM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR SAYS HE WORKS WITH THE FMC VENDOR DAILY AND THEY ARE WELL AWARE OF THE PROBLEM AND ARE WORKING ON IT. DO NOT THINK ASRS COULD ADD ANYTHING TO WHAT IS BEING DONE.