Date: 202007
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Navigational Equipment and Processing
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Communication Breakdown; Confusion; Human-Machine Interface
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Inflight Event / Encounter Unstabilized Approach
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Regained Aircraft Control; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Procedure
Primary problem: Ambiguous

Narrative: On the ZZZZZ5 arrival into ZZZ; ZZZ Center left us approximately 5;000 feet above our VNAV profile. The last clearance received from center was to descend and maintain 13;000. I checked in with approach descending to 13;000; NOT via the arrival. Upon arrival at ZZZZZ [fix]; I requested lower twice from approach. Based on the altitude indicated on the arrival; we were approximately 5;000 feet high at that fix. After the second request for lower; the Approach Controller responded with 'weren't you cleared to descend via?' I responded 'no.' He immediately issued us a descent to 4;000 and cleared us for the ILS approach. At this point we were still trying to 'catch up' with altitudes. The Controller came back and issued us descent to 2;500. The Captain queried the controller if we were cleared for the ILS and he responded affirmatively. The Captain had us in LNAV/VNAV and selected 1;600 feet for the FAF. I was configuring the aircraft when we leveled off at 1;600 feet. I looked outside; saw we were looking 'flat' for the approach and then the Controller issued us a low altitude alert. I responded that we had the field in sight. We maintained altitude until crossing the FAF; continued on the visual approach and landed without incident. We were confused that the aircraft did not descend to the proper altitude on the approach and after discussion concluded that the VNAV PATH did not capture. We also discussed that the VNAV had been written up recently; but it is unclear if it was related. [Causes were] ZZZ Center leaving us high on the arrival and not clearing us to descend via the arrival. ZZZ1 approach control not listening to the check in and assuming we were cleared to descend via. Our decision to continue knowing we were behind the descent profile. I have had ZZZ Center leave me high on this arrival every time I have flown it. Controllers are task saturated right now with operating multiple sectors. This may account for leaving us high and also the approach controller not comprehending the information given on check in. We were left high and instead of asking for vectors to lose altitude; we continued.


Second narrative: ZZZ Center began limiting our altitudes while we descended on the ZZZZZ5 arrival to ZZZ resulting in us being 4-5;000 feet high 25 miles from the field. We were switched to Approach and had to ask for lower because the approach controller didn't realize we were not 'descending via.' We descended in level change at 220 knots from 13;000 feet to 5;000 starting 20-some miles from the field trying to regain the VNAV path. Approach cleared us to 4;000 feet and then cleared us for the ILS XXR from ZZZZZ. I fumbled around in the box to join the arrival to the approach; and then approach cleared us to descend to 2;500 causing more confusion. 'Aren't we cleared for the approach?' 'Yes.' I dialed 1;600 feet for the FAF into the altitude window satisfied we had captured the path; and I armed Approach thinking we were still above the glideslope. As we broke out of the scattered layer around 2;000 feet we got a 'low altitude alert' from approach control while the autopilot leveled us at 1;600 feet. I thought we had gotten a brief GPWS 'Terrain' closure warning at the same time; although the FO does not recall that. We told the controller we had the field in sight and continued visually for a stable VMC approach and landing. On debrief the FO and I concluded the most logical explanation was that we had never captured the path and had blown through the step-down altitudes of 2;500 and 2;200 in level change while thinking we were on the VNAV path. The following day the FO reminded me that the aircraft we had flown during the event; XXX; had had a previous write-up that VNAV would not engage on takeoff. That knowledge left us wondering what was the actual cause of the busted altitudes.[Caused by] a series of events had led to leaving us high and time-compressed on the approach.The FO had experienced this a few times before when on the arrival to ZZZ; and we had discussed it in our arrival brief. ATC could have handled the center to approach handoff and our approach clearance better. I should have asked for random vectors when I realized we were being rushed.


Synopsis: Air carrier flight crew reported the flight was left high by ATC on arrival which contributed to missing step down altitudes and receiving a low altitude alert as the flight descended.