Narrative:

We were at cruise; cleared direct atl and; shortly thereafter; direct bna. It was VMC the whole flight so we anticipated a straight in to bna. After passing atl we were in our descent and had leveled off at FL240. Center mentioned he needed us back on the swfft RNAV STAR and we were cleared direct swfft for the swfft one north transition. We loaded the arrival and headed direct to swfft. We were trying to determine the north transition which is not mentioned on the plates. That created confusion. I called center to confirm the waypoints he wanted us to fly; but he was not responsive. We were not cleared to descend 'via' the swfft one arrival and center did not have us descend to a lower altitude that would have been consistent with crossing altitudes at swfft. Center handed us off to approach control who then asked why we were still at FL240. We advised we had not been cleared to descend below FL240. There was a short delay and he cleared us down to 5;000 ft and we then began a descent to land with vectors to get down. We landed uneventfully. The first officer and I discussed the fact we needed to descend to cross swfft but there were no instructions from center to make that happen.I have not flown this RNAV arrival before and it is not in the company's current safety report data base so maybe it is new. There was precious time spent trying to determine the north transition as requested by center. I still cannot determine what the north transition is. The PF noted a descent was needed and had we been given a timely clearance we would have been able make the altitudes per the arrival. I will be far more proactive in a scenario like this in the future. I was expecting a clearance from either center or approach.

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Original NASA ASRS Text

Title: A B737-800 flight crew inbound to Nashville was cleared to fly the SWFFT RNAV STAR; but because they were not 'cleared via' and had not received an 'independent' descent clearance; did not descend to cross SWFFT as charted. Approach Control ultimately provided descent clearance and vectors as necessary.

Narrative: We were at cruise; cleared direct ATL and; shortly thereafter; direct BNA. It was VMC the whole flight so we anticipated a straight in to BNA. After passing ATL we were in our descent and had leveled off at FL240. Center mentioned he needed us back on the SWFFT RNAV STAR and we were cleared direct SWFFT for the SWFFT ONE North Transition. We loaded the arrival and headed direct to SWFFT. We were trying to determine the North transition which is not mentioned on the plates. That created confusion. I called Center to confirm the waypoints he wanted us to fly; but he was not responsive. We were not cleared to descend 'via' the SWFFT ONE arrival and Center did not have us descend to a lower altitude that would have been consistent with crossing altitudes at SWFFT. Center handed us off to Approach Control who then asked why we were still at FL240. We advised we had not been cleared to descend below FL240. There was a short delay and he cleared us down to 5;000 FT and we then began a descent to land with vectors to get down. We landed uneventfully. The First Officer and I discussed the fact we needed to descend to cross SWFFT but there were no instructions from Center to make that happen.I have not flown this RNAV arrival before and it is not in the company's current safety report data base so maybe it is new. There was precious time spent trying to determine the North Transition as requested by Center. I still cannot determine what the North Transition is. The PF noted a descent was needed and had we been given a timely clearance we would have been able make the altitudes per the arrival. I will be far more proactive in a scenario like this in the future. I was expecting a clearance from either Center or Approach.

Data retrieved from NASA's ASRS site as of July 2013 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.