WHILE FLYING TRISS RNAV SID; TXK TRANSITION FROM DFW; MD81 FLT CREW NOTICES A BREAK IN THE FMS RTE WITH NO COMMENSURATE RTE DISCONTINUITY ON THE CDU. ATTEMPTS TO RECONCILE THE RTE RESULTED IN MISSING WAYPOINTS. MANUAL ENTRY OF ALL WAYPOINTS ON THE SID/TRANSITION WERE REQUIRED.

Narrative

CLRED TRISS.TXK. NORMAL PREFLT FMS PROCS PERFORMED DURING PREFLT. ONCE AIRBORNE APCHING TRISS INTXN NOTICED WHAT APPEARED TO BE A DISCONTINUITY (IE; NO MAGENTA LINE) ON NAV DISPLAY. CAPT HAD SAME LACK OF MAGENTA LINE ON HIS NAV DISPLAY; TOO. REFERENCED FMS FOR ANY DISCONTINUITY; BUT THERE WASN'T ONE. WHILE TRYING TO FIGURE OUT WHAT WAS UP; ARTCC CALLED TO REMIND US TO MAKE TURN TOWARDS SHERO INTXN (ABOUT A 10 DEG TURN FROM TRISS TO SHERO USING HDG SEL AND REPROGRAMMED TRISS2.TXK IN FMS. CAPT EXECUTED INPUT AND SELECTED NAV. MAGENTA LINE REAPPEARED FOR ROUTING FROM TRISS TO SHERO. THEN; TXK VANISHED FROM VIEW ON NAV DISPLAY AND MAGENTA LINE THEN SHOWED A ROUTING FROM SHERO DIRECT TO MATIE -- NO TXK. SAW THIS OCCUR WITH MY OWN EYES! CAPT THEN MANUALLY INPUT A RTE FROM SHERO TO TXK THEN MATIE. SELECTED NAV. LATER CAPT TO WRITE UP FMS FOR CORRUPT NAV DATA.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR REITERATED THE DICHOTOMY OF A BREAK IN THE MAP RTE DISPLAY AND THE LACK OF A RTE DISCONTINUITY WARNING ON THE CDU. RPTR WAS UNCERTAIN; HOWEVER; WHETHER THE RTE DISPLAY WAS PICKED UP AGAIN AFTER TXK; ONLY THAT IT STOPPED AT TRISS. HE WAS ABSOLUTELY CERTAIN; THOUGH; THAT TXK DID IN FACT DISAPPEAR WHEN THE CORRECTION WAS MADE AND THE MAGENTA RTE LINE WENT DIRECT TO MATIE FROM SHERO.