Narrative:

On descent into slc; salt lake center changed our cleared arrival procedure from the DELTA4 to the QWENN4 and we were instructed to cross frnzy at 15K feet. Passing through 21K; ATC instructed us to turn right to a heading of 090 vectors for leehy and the LEEHY4 arrival due to a pilot report of severe turbulence at 15K feet over the frnzy intersection. As pilot monitoring; I read back the instructions while the flying pilot engaged heading mode on the autopilot and complied with the turn. We were then instructed to maintain 16K feet and were given an altimeter setting .13 lower than the ATIS value which was only 5 min old. Upon query the issued setting of 29.32 was verified (the slc TRACON later confirmed the ATIS value of 29.45). I then reset the altitude selector to 16K feet and began to reprogram the FMS for the new arrival as we began to experience continuous moderate turbulence and moderate rime icing associated with the frontal passage in the area. While we never experienced severe turbulence as reported by other arriving aircraft; it was certainly making it more difficult to make the required programming inputs. We made a PIREP of our flight conditions and then as we entered the high teens on altitude; we were cleared direct to leehy for the QWENN4 arrival. I read back the instructions without a correction; but having just been told to expect the leehy arrival; this instruction seemed incorrect. In recalling the chart for the QWENN4 on my efb; the suspicions we were actively discussing as a crew were confirmed in that leehy was not contained in the QWENN4 STAR. We addressed this concern to the ARTCC controller who admitted we were mis-cleared and to now proceed direct to leehy for the LEEHY4. Immediately after; a follow-up call was made by ATC asking us if we were still descending to 15K or if we had copied the revised instruction to maintain 16K. We reported that we were leveling at 16K but immediately recognized our error in missing the fact that we had just transitioned through FL180 and had not yet set our local altimeter setting.with the extremely low pressure in the slc area; it made for a descent through our assigned altitude of nearly 500 feet before we made the barometric pressure setting change to coax the autopilot back to 16K feet. The remainder of the flight was uneventful as we transitioned into the lda/DME approach to runway 35; breaking out of IMC 1000 ft AGL. In retrospect; we should have requested radar vectors in lieu of our 5th STAR clearance in a critical phase of flight through challenging flight conditions (moderate ice and continuous moderate turbulence with reports to expect worse). The numerous changes to our assigned altitudes; headings; fixes; and stars coupled with the flight conditions made for the 'perfect storm' of distraction to allow the two of us to miss our FL180 callouts and associated flows/checklists. At the end of the day we certainly appreciated the favorable routing away from the severe turbulence and the quick catch by the ARTCC controller as we missed our level off. It was apparent that both the radar room and the cockpit were task saturated at an inopportune time. Despite all challenges; more emphasis and care need to be applied by myself and my flying pilot first officer to not miss an important primary flight task such as transition level.

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Original NASA ASRS Text

Title: C56X Captain reported overshooting his cleared altitude during descent into SLC when the altimeter was not set to local descending out of FL180. Numerous arrival changes contributed to the deviation.

Narrative: On descent into SLC; Salt Lake Center changed our cleared arrival procedure from the DELTA4 to the QWENN4 and we were instructed to cross FRNZY at 15K feet. Passing through 21K; ATC instructed us to turn right to a heading of 090 vectors for LEEHY and the LEEHY4 arrival due to a pilot report of severe turbulence at 15K feet over the FRNZY intersection. As pilot monitoring; I read back the instructions while the flying pilot engaged heading mode on the autopilot and complied with the turn. We were then instructed to maintain 16K feet and were given an altimeter setting .13 lower than the ATIS value which was only 5 min old. Upon query the issued setting of 29.32 was verified (the SLC TRACON later confirmed the ATIS value of 29.45). I then reset the altitude selector to 16K feet and began to reprogram the FMS for the new arrival as we began to experience continuous moderate turbulence and moderate rime icing associated with the frontal passage in the area. While we never experienced severe turbulence as reported by other arriving aircraft; it was certainly making it more difficult to make the required programming inputs. We made a PIREP of our flight conditions and then as we entered the high teens on altitude; we were cleared direct to LEEHY for the QWENN4 arrival. I read back the instructions without a correction; but having just been told to expect the LEEHY arrival; this instruction seemed incorrect. In recalling the chart for the QWENN4 on my EFB; the suspicions we were actively discussing as a crew were confirmed in that LEEHY was not contained in the QWENN4 STAR. We addressed this concern to the ARTCC controller who admitted we were mis-cleared and to now proceed direct to LEEHY for the LEEHY4. Immediately after; a follow-up call was made by ATC asking us if we were still descending to 15K or if we had copied the revised instruction to maintain 16K. We reported that we were leveling at 16K but immediately recognized our error in missing the fact that we had just transitioned through FL180 and had not yet set our local altimeter setting.With the extremely low pressure in the SLC area; it made for a descent through our assigned altitude of nearly 500 feet before we made the barometric pressure setting change to coax the autopilot back to 16K feet. The remainder of the flight was uneventful as we transitioned into the LDA/DME approach to Runway 35; breaking out of IMC 1000 ft AGL. In retrospect; we should have requested radar vectors in lieu of our 5th STAR clearance in a critical phase of flight through challenging flight conditions (moderate ice and continuous moderate turbulence with reports to expect worse). The numerous changes to our assigned altitudes; headings; fixes; and STARs coupled with the flight conditions made for the 'perfect storm' of distraction to allow the two of us to miss our FL180 callouts and associated flows/checklists. At the end of the day we certainly appreciated the favorable routing away from the severe turbulence and the quick catch by the ARTCC controller as we missed our level off. It was apparent that both the radar room and the cockpit were task saturated at an inopportune time. Despite all challenges; more emphasis and care need to be applied by myself and my flying pilot first officer to not miss an important primary flight task such as transition level.

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.