Narrative:

En route tpa-mia level at FL190, first officer flying. ZMA cleared us to cross the worpp intersection at 6000 ft. First officer started down (autoplt engaged in heading mode rather than navigation mode). I made my PA to the passenger, got off frequency to pick up the ATIS and also to make my in-range call to the company. By the time I came back on, we were about 4 mi west of worpp and descending through 6600 ft. I noticed this and asked my first officer where he was going and he said that he thought that he had the autoplt in the navigation mode, not the heading mode. I think the problem was that nobody was flying the airplane. I feel that we needed to be more vigilant about what is going on inside the flight deck and not just outside.

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Original NASA ASRS Text

Title: COMMUTER FLT GETS OFF COURSE ON CYPRESS 3 ARR INTO MIA WHEN FO IS OPERATING AUTOPLT IN THE HDG MODE VERSUS NAV MODE. PIC WAS OFF FREQ, GIVING PA, GETTING ATIS AND GIVING COMPANY A CALL. HE NOTES FO'S DEV LATER ON.

Narrative: ENRTE TPA-MIA LEVEL AT FL190, FO FLYING. ZMA CLRED US TO CROSS THE WORPP INTXN AT 6000 FT. FO STARTED DOWN (AUTOPLT ENGAGED IN HDG MODE RATHER THAN NAV MODE). I MADE MY PA TO THE PAX, GOT OFF FREQ TO PICK UP THE ATIS AND ALSO TO MAKE MY IN-RANGE CALL TO THE COMPANY. BY THE TIME I CAME BACK ON, WE WERE ABOUT 4 MI W OF WORPP AND DSNDING THROUGH 6600 FT. I NOTICED THIS AND ASKED MY FO WHERE HE WAS GOING AND HE SAID THAT HE THOUGHT THAT HE HAD THE AUTOPLT IN THE NAV MODE, NOT THE HDG MODE. I THINK THE PROB WAS THAT NOBODY WAS FLYING THE AIRPLANE. I FEEL THAT WE NEEDED TO BE MORE VIGILANT ABOUT WHAT IS GOING ON INSIDE THE FLT DECK AND NOT JUST OUTSIDE.

Data retrieved from NASA's ASRS site as of July 2007 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.