Narrative:

Upon arriving into the las area; we were cleared to descend via the tyssn.5 RNAV arrival. On that arrival; the controller restricted us to 12000 feet as we neared kaddy. After passing kaddy we were given numerous changes to heading; altitude and speed. While being vectored for a visual approach to runway 19R at las; the controller and pilot workload was extremely high and the reported turbulence was moderate to severe in the las area. Surface winds were reported 190@23g36 and all arriving traffic was requesting runways 19L and 19R. Where our confusion started was when we were told by ATC to bring up the SITEE2 RNAV visual to 19R. We misunderstood this as a charted visual approach and weren't expecting to get another arrival within twenty or so miles of the airport in visual conditions. After searching through our approaches; we told ATC we didn't have it in our database. ATC told us it was the SITEE2 RNAV arrival and to let them know when we had it loaded. During this confusion; we were in a rush to get the arrival loaded and briefed resulting in a misunderstood instruction of a 'heading change only' to be a heading and altitude change to 5000 feet. ATC alerted us to climb immediately back to 7000 feet as we reached about 5700 feet. We were handed off to the final controller; given a descent to 5200 feet; speed of 170 knots and a heading to intercept final. The approach and landing continue without further issues. The crew was never notified to call a number but I reached out to ATC to understand where the issues were and understand how to avoid this in the future.

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Original NASA ASRS Text

Title: CL300 flight crew reported receiving a low altitude alert after departing the cleared altitude due to a clearance misunderstanding.

Narrative: Upon arriving into the LAS area; we were cleared to descend via the TYSSN.5 RNAV arrival. On that arrival; the Controller restricted us to 12000 feet as we neared KADDY. After passing KADDY we were given numerous changes to heading; altitude and speed. While being vectored for a visual approach to Runway 19R at LAS; the Controller and pilot workload was extremely high and the reported turbulence was moderate to severe in the LAS area. Surface winds were reported 190@23G36 and all arriving traffic was requesting Runways 19L and 19R. Where our confusion started was when we were told by ATC to bring up the SITEE2 RNAV Visual to 19R. We misunderstood this as a charted visual approach and weren't expecting to get another arrival within twenty or so miles of the airport in visual conditions. After searching through our approaches; we told ATC we didn't have it in our database. ATC told us it was the SITEE2 RNAV arrival and to let them know when we had it loaded. During this confusion; we were in a rush to get the arrival loaded and briefed resulting in a misunderstood instruction of a 'heading change only' to be a heading and altitude change to 5000 feet. ATC alerted us to climb immediately back to 7000 feet as we reached about 5700 feet. We were handed off to the Final Controller; given a descent to 5200 feet; speed of 170 knots and a heading to intercept final. The approach and landing continue without further issues. The crew was never notified to call a number but I reached out to ATC to understand where the issues were and understand how to avoid this in the future.

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.