Narrative:

Latest ATIS called for runway 36L/right for landing runways. We were told to expect runway 18R for landing. Approaching clt via the unarm arrival; clt approach control asked if we were making a left turn northbound. We had been flying the unarm arrival. At this time a turn north was requested without any traffic conflict. Remainder of descent; approach and landing were routine. Original filed was crlnc was...'grd adena 1 clt.' at gate in ZZZ a revised segment was issued 'grd unarm.' flight crew saw unarm and incorrectly assumed unarm 1 arrival. Both adena 1 and unarm 1 arrivals overfly unarm intersection. After landing a review of the revised segment was studied to determine where the confusion lay. It was the 'unarm' that led the crew to mistake the arrival. The adena 1 arrival was the correct routing. Closer attention to this detail will be necessary in future. In retrospect; why is 'unarm' listed as a revised segment? Adena 1 and unarm 1 stars both overfly unarm! A revised segment of 'grd unarm' is redundant. Nothing is different a potential mistake is in the making; as evidenced by our actions. There is probably a reasonable explanation for it; but from a pilot's perspective it is quite a common presentation to have a 'revised segment' that is really no different than filed.callback conversation with reporter revealed the following information: the reporter stated that; of the potential misinterpretations possible; they chose the worst. Assuming they had received a 'revised' clearance via the unarm STAR caused them to not be concerned passing unarm. Had they considered unarm a clearance limit they would certainly have queried approach control for further clearance prior to entering a hold. They would have received clarification and a track deviation would not have occurred. As it was; the track deviation had to take place before anyone was aware of the misinterpretation. Reporter reiterated that; had not the revised segment been printed in the first place; neither would have been a possibility. For the simple reason that the statement revised nothing except the ability to be clearly understood and easily misinterpreted.

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Original NASA ASRS Text

Title: CONFUSING LANGUAGE OF REVISED SEGMENT OF PDC RESULTS IN TRACK DEVIATION AT ARR ARPT FOR A319 FLT CREW.

Narrative: LATEST ATIS CALLED FOR RWY 36L/R FOR LNDG RWYS. WE WERE TOLD TO EXPECT RWY 18R FOR LNDG. APCHING CLT VIA THE UNARM ARR; CLT APCH CTL ASKED IF WE WERE MAKING A L TURN NORTHBOUND. WE HAD BEEN FLYING THE UNARM ARR. AT THIS TIME A TURN N WAS REQUESTED WITHOUT ANY TFC CONFLICT. REMAINDER OF DSCNT; APCH AND LNDG WERE ROUTINE. ORIGINAL FILED WAS CRLNC WAS...'GRD ADENA 1 CLT.' AT GATE IN ZZZ A REVISED SEGMENT WAS ISSUED 'GRD UNARM.' FLT CREW SAW UNARM AND INCORRECTLY ASSUMED UNARM 1 ARR. BOTH ADENA 1 AND UNARM 1 ARRIVALS OVERFLY UNARM INTXN. AFTER LNDG A REVIEW OF THE REVISED SEGMENT WAS STUDIED TO DETERMINE WHERE THE CONFUSION LAY. IT WAS THE 'UNARM' THAT LED THE CREW TO MISTAKE THE ARR. THE ADENA 1 ARR WAS THE CORRECT ROUTING. CLOSER ATTENTION TO THIS DETAIL WILL BE NECESSARY IN FUTURE. IN RETROSPECT; WHY IS 'UNARM' LISTED AS A REVISED SEGMENT? ADENA 1 AND UNARM 1 STARS BOTH OVERFLY UNARM! A REVISED SEGMENT OF 'GRD UNARM' IS REDUNDANT. NOTHING IS DIFFERENT A POTENTIAL MISTAKE IS IN THE MAKING; AS EVIDENCED BY OUR ACTIONS. THERE IS PROBABLY A REASONABLE EXPLANATION FOR IT; BUT FROM A PLT'S PERSPECTIVE IT IS QUITE A COMMON PRESENTATION TO HAVE A 'REVISED SEGMENT' THAT IS REALLY NO DIFFERENT THAN FILED.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT; OF THE POTENTIAL MISINTERPRETATIONS POSSIBLE; THEY CHOSE THE WORST. ASSUMING THEY HAD RECEIVED A 'REVISED' CLRNC VIA THE UNARM STAR CAUSED THEM TO NOT BE CONCERNED PASSING UNARM. HAD THEY CONSIDERED UNARM A CLRNC LIMIT THEY WOULD CERTAINLY HAVE QUERIED APCH CTL FOR FURTHER CLRNC PRIOR TO ENTERING A HOLD. THEY WOULD HAVE RECEIVED CLARIFICATION AND A TRACK DEVIATION WOULD NOT HAVE OCCURRED. AS IT WAS; THE TRACK DEVIATION HAD TO TAKE PLACE BEFORE ANYONE WAS AWARE OF THE MISINTERPRETATION. RPTR REITERATED THAT; HAD NOT THE REVISED SEGMENT BEEN PRINTED IN THE FIRST PLACE; NEITHER WOULD HAVE BEEN A POSSIBILITY. FOR THE SIMPLE REASON THAT THE STATEMENT REVISED NOTHING EXCEPT THE ABILITY TO BE CLEARLY UNDERSTOOD AND EASILY MISINTERPRETED.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.