Light Transport
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness; Communication Breakdown; Confusion
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Human Factors
SoCal gave us VTU SADDE8 we verified all points and altitudes. They then cleared us direct FIM for the SADDE8 which is on a different transition. We verified all points and re-entered the missing altitudes and speeds. Then we were given direct SYMON cross at 12;000 feet. We initiated a descent at this point. Then we were given IRNMN2 direct IRNMN. Which creates the question of what altitude? Then we were given descend via. I was doing 1 altitude at a time while First Officer was attempting to program and dual verify all points. I may have missed JUUSE by a few 100 feet as I was on a steep descent we were time compressed by ATC. This was a short flight. Each SoCal frequency change involved a new arrival; new direct to way point; and new altitude. And a runway change.In retrospect I would have asked for delay vectors or told ATC we were unable to switch arrivals or runways this close to destination.
On the short flight from ZZZ to LAX we were cleared for the SADDE8 and expect Runway 24R. We verified speeds an altitudes were correct in FMS. We were cleared direct to VTU. Then as we got close we were cleared to FIM which is on another transition; which meant re-entering the arrival into the FMS and re-verifying altitudes for the descent. ATC gave us Cross SYMON AT 12;000 feet. As we began that we were assigned the IRNMN2 direct IRNMN with a descend via and Runway 25L. Then a frequency change. I became task saturated with NAV changes; frequency changes; verifications and perf programming. Pilot flying had to make a steep descent to make the 9;000 feet at JUUSE. ATC informed us we had missed that altitude although both of us thought we made it just in time. After that we were assigned another lower altitude; which we complied with. While using VNAV then changing arrivals there is a slight lag in the automation. In consequence; it would be better not to accept such changes when already beginning one procedure. Particularly as the three different arrivals/transitions are virtually identical.
Corporate jet Captain reported receiving multiple arrival changes on approach to LAX resulting in confusion and missing a crossing restriction.