Narrative:

Oakland center gave us a late descent clearance. I believe that I even asked for lower. We were given a lower altitude and told to contact norcal approach immediately. After switching frequencies; we were given an odd clearance; instead of a clear and concise descend via; we got a descend and maintain 16;000 feet at pnnen. This is different than the published altitudes and the new altitude was inserted and verified by both pilots. Additionally; the altitude at the preceding fixes were deleted because we understood this as a descend and maintain clearance; and not a descend via clearance. After many more norcal frequencies; we were given an odd descend clearance of cross pnnen at 16;000 feet then descend via to 14;000 feet. It turns out that there was a twin otter at 13;000 feet. Once we had visual contact with that aircraft we were given maintain visual separation descend via at pilots discretion. We cleared the area with the traffic and continued the descend via all the way to 4000 feet with no issues. In fact; when the final approach controller passed us the phone number to call oakland center it was a little concerning to be flying a visual arrival and wondering what we did wrong. LNAV/VNAV path was used during the arrival and we complied with the altitude restrictions. We were given speed at our discretion. We were both very surprised that oakland/norcal had any concerns and we contacted our ATC representative upon landing uneventfully at smf.ATC should give very simple clearances if they can't authorized the entire descend via STAR; due to traffic. For example cleared direct to pnnen descend and maintain 16;000. Don't start and stop a descend via clearance. ATC should automatically give altitude relief is they start the aircraft down past the normal top of descent point. This may be hard for them to know and I will continue to pay close attention to this phase of flight.

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Original NASA ASRS Text

Title: B737 First Officer was concerned that he was not given a descend via clearance on a STAR; but was stepped down for traffic.

Narrative: Oakland Center gave us a late descent clearance. I believe that I even asked for lower. We were given a lower altitude and told to contact NorCal Approach immediately. After switching frequencies; we were given an odd clearance; instead of a clear and concise descend via; we got a descend and maintain 16;000 feet at PNNEN. This is different than the published altitudes and the new altitude was inserted and verified by both pilots. Additionally; the altitude at the preceding fixes were deleted because we understood this as a descend and maintain clearance; and not a descend via clearance. After many more NorCal frequencies; we were given an odd descend clearance of cross PNNEN at 16;000 feet then descend via to 14;000 feet. It turns out that there was a Twin Otter at 13;000 feet. Once we had visual contact with that aircraft we were given maintain visual separation descend via at Pilots Discretion. We cleared the area with the traffic and continued the descend via all the way to 4000 feet with no issues. In fact; when the final Approach Controller passed us the phone number to call Oakland Center it was a little concerning to be flying a visual arrival and wondering what we did wrong. LNAV/VNAV PATH was used during the arrival and we complied with the altitude restrictions. We were given speed at our discretion. We were both very surprised that Oakland/NorCal had any concerns and we contacted our ATC Representative upon landing uneventfully at SMF.ATC should give very simple clearances if they can't authorized the entire descend via STAR; due to traffic. For example cleared direct to PNNEN descend and maintain 16;000. Don't start and stop a descend via clearance. ATC should automatically give altitude relief is they start the aircraft down past the normal Top of Descent point. This may be hard for them to know and I will continue to pay close attention to this phase of flight.

Data retrieved from NASA's ASRS site 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.