Medium Transport
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Workload; Confusion; Distraction; Situational Awareness; Troubleshooting
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Procedure; Chart Or Publication; Human Factors
During our arrival into LAX; we were given a series of speed changes beginning with LAX Center. First it was slow to 260; then increase to 280; then maintain 280 but comply with the STAR. We were also cleared to descend via the HLYWD1. When we checked on with SoCal Approach; the controller told us to slow to 230 before any further descent. The Pilot Flying (PF) used VS mode to arrest the descent to facilitate the speed reduction and began decreasing the speed. We were at around 500 FPM down when the controller said to stop descending and slow to 210. I initially was a little confused about the clearance - whether it meant to stop at our current altitude or if it meant that we wouldn't receive a further descent beyond the arrival until we slowed. Evidently it was the former; but I was unable to clarify due to frequency congestion. When I was able to ask for more information about our clearance; we were already slowed and level at around 16000; and I asked if we'd missed an instruction at some point; due to the unusual speed request. The controller proceeded to give a long explanation about a new procedure that requires 50 or 60 miles of separation to get an IFR departure out of HHR. This left us very high; and the controller then asked us to expedite to 10000. We were beginning our descent and then the controller gave us another speed change; this time to 300 and to give him the best rate down. The PF was rapidly trying to manipulate the automation modes to comply and the controller kept asking for more descent rate. We were doing something like 3000 FPM down and increasing; when we both realized we were unclear about our further clearance. I inquired about what to do after 10000 and the controller just said to get down as fast as possible. At this point we were still high and fast; but pretty far out. We were changed to the final approach controller and given a speed reduction to 250 and then cleared for the ILS 25L approach. We were then high again; and the PF used a vertical direct-to to command the aircraft to rejoin the descent path. I was looking away momentarily to change my chart from the arrival to the approach when the PF inadvertently activated the change before I could review it. I was concerned that we might miss the crossings at KRAIN; TAROC; and DYMMO but we were very high and I am pretty sure we were well above them. While trying to get back 'on profile' the PF accidentally descended below the VNAV path to catch the ILS glide slope just outside HUNDA. I didn't see it right away because I was monitoring our speed reduction and talking to the tower controller; but as I noticed it I remarked to watch the altitude at HUNDA and on my altimeter we were around 100 feet low. During the debrief the PF said that her altimeter read only about 50 feet low. We talked about the challenges of the arrival and approach and how the altitudes on the approach are mandatory crossing altitudes and are particularly important at LAX due to the airspace below the glideslope. In thinking this over after the fact; I think if I had taken the controls and used Touch Control Steering (TCS) to override the autopilot; I probably could have leveled us in time to not be low at HUNDA. It was so close and there was so little time; that by the time I noticed it and said something to the PF it was too late. A few moments earlier and I could have said something and then made the correction. Taking the controls from a First officer (FO) has always been a last resort action for me; but perhaps I should have been more forward in this instance. Also in retrospect; I could have asked for a heading and an altitude back during the confusing descent instructions; positioned the aircraft in a more obvious condition with a clearer clearance; then rejoined the arrival in a more normal configuration and position.
EMB-175 Pilot reported of confusion flying into LAX with speeds and restrictions from ZLA and SCT.