Light Transport
Flight Crew Instrument
Flight Crew Total 19400
Situational Awareness
No Specific Anomaly Occurred All Types
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Airspace Structure; Environment - Non Weather Related; Procedure; Human Factors
IFR flight plan via the RNAV Arrival transition. This is an arrival that we fly approximately 1 to 2 times on average per week to our home base. Under most normal descents we are given the following clearance: 'Descend VIA the [RNAV Arrival]. The controllers don't issue any altitudes and we fly a normal vertical profile; as depicted on the arrival chart; on the autopilot using the VNAV function on the autopilot; having verified the crossing altitudes in the FMS. On this particular event; ARTCC; instead of issuing a normal RNAV arrival profile; gave multiple altitude step downs; approximately 6; starting from around 24;000 feet down to 11;000 feet. At this time we were talking to TRACON and they said to descend to 6;000 feet via the [RNAV] arrival. I 'felt' as if there was a trainee on the radio; as normally they would not give the 'bottom' altitude to you as part of the clearance. Shortly after this instruction was issued; another controller came on the frequency. At this point the 'TO' fix in front of me on the FMS was a fix which had a crossing of 'at or above 10;000'. We selected 6;000 ft in the altitude alerter; the vertical deviation needle was centered and the 'VNAV' autopilot mode was engaged. We crossed the fix at 10;000 and continued on the RNAV profile. Shortly after that crossing we were told to fly a heading of 360 for vectors to the Runway. I feel that the RNAV arrival should not have been used due to the multiple nonstandard altitude interruptions. The RNAV arrival descent should only be given when the flight crew can continue to the lowest depicted altitude 'without' multiple changes to the profile. The crew workload is already high in this environment; and by throwing in multiple changes at the last minute presents an even higher probability of errors; both on the controllers side along with the flight crew.
The pilot was cleared for an RNAV Arrival. The pilot was assigned altitudes by ATC instead of being allowed to descend on their own via the RNAV profile.