AN MD80 CREW ON THE DFW TRISS2/TXK WAS FLYING DIRECT TXK AFTER A DIRECT TRISS CLRNC BECAUSE THE INTERVENING WAYPOINTS WERE DROPPED FROM THE FMS. ATC REDIRECTED RTE.

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CLRED TRISS2 RNAV DEP. BEFORE REACHING CUZEN; DFW DEP GAVE US A R TURN DIRECT TRISS DIRECT TXK. THIS IS WHAT I THOUGHT I HEARD AND WHAT I WAS TO FLY. WE GOT HIGHER ALT THEN CHANGED CTLRS. NEXT CTLR GAVE US A CLB TO 23000 FT THEN 28000 FT AND WE WERE CHANGED TO ANOTHER CTLR WITH NO FURTHER INFO ON ROUTING. THE CTLR GAVE US A CLB TO 33000 FT BUT NOT NEW CLRNC. APCHING TRISS; I SET IN 116.3 VOR FOR TXK AS BACKUP; BUT THE GPS HAD TRISS DIRECT TXK. I DO NOT REMEMBER CHANGING THE SID TO GO TRISS DIRECT TXK. IT SHOULD HAVE READ SHERO TXK BUT I DID NOT CHANGE THIS BUT THE CLRNC IN MY MIND WAS TRISS TXK; SO NO CHANGE WAS NEEDED. AFTER PASSING TRISS; CTLR ASKED WHERE WE WERE GOING. WE SHOULD BE R OF COURSE. I READ BACK THAT THE DEP CTLR GAVE US DIRECT TRISS DIRECT TXK AND THIS IS WHAT WE WERE DOING. HE STATED WE STILL HAD TO GO TO SHERO AND IT PROBABLY DROPPED OUT. WELL I DID NOT HEAR OR READ BACK DIRECT TRISS RESUME THE DEP. I HEARD DIRECT TXK AFTER TRISS. FO WAS NOT SURE OF THIS CLRNC BUT IF WE DID NOT GET IT HOW DID SHERO DROP OUT OF THE GPS IF WE WENT TO A POINT DIRECT BEFORE SHERO. SHERO SHOULD HAVE BEEN IN THERE AS IT WAS BEFORE THE DEP. THE CTLR DID MENTION THAT SEVERAL PLTS HAD THIS DROP OUT ON THEM SO WE WERE NOT THE FIRST AND NOT THE LAST. BUT WHY IS IT DROPPING OUT??? WE BOTH HAD RECURRENT TRAINING AND THIS WAS NOT ONE OF THE ITEMS THAT WAS MENTIONED AS A PROBLEM AREA; BUT I FEEL IT IS. IN MY MIND WE HAD DIRECT TRISS DIRECT TXK; WHICH DID SEEM ODD; BUT WE GOT IT FROM DEP CTL. NEVER REACHED CUZEN AND IT WAS LIKE CTLR WAS TRYING TO SHORTEN UP THE COURSE FOR TFC? THIS NEEDS TO BE REVIEWED IF IT IS DROPPING OUT FROM GPS. ACR Y CREW HAD THE SAME THING WITH THEIR DEP SO SOUNDS LIKE A PROBLEM. NOTHING ELSE WAS MENTIONED AFTER HE GAVE US A 20 DEG TURN TO R THEN GAVE US DIRECT TXK BEFORE SHERO. SO WE CHANGED FREQ AND NOT ANOTHER WORD ABOUT IT. COULD HAVE MISSED THE CLRNC BUT THEN STILL THE ISSUE; WHY DID SHERO GET DELETED FROM SID? GOING DIRECT TO A POINT DOES NOT TAKE OUT THE POINT AFTER THE DIRECT POINT.