ERJ-175 flight crew reported pilot flying being behind the aircraft; failed to communicate this to pilot monitoring resulted in altitude overshoot with low altitude alert.
Synopsis
ERJ-175 flight crew reported pilot flying being behind the aircraft; failed to communicate this to pilot monitoring resulted in altitude overshoot with low altitude alert.
Narrative
Upon arrival into ZZZ from the north. We briefed the ILS XX as was advertised on the ATIS. Past the top of descent the ATIS changed to advertise the Visual XY. When we requested the RNP XY Approach advised they couldn't accommodate the approach for around 5 mins and asked if we wanted to hold at ZZZZZ or take the visual. We decided we could hold and wait and then take the RNP XY. ATC then assigned a hold on the localizer as we were quickly approaching the holding fix in a non standard manner. While we were loading the approach another aircraft canceled IFR and ATC cleared us for the ILS XX which we were now above profile for. In an effort to get back on profile we slowed and configured early and then used FPA (Flight Path Angle) to path onto the GS. While I was monitoring the speed profile I did not notice us briefly descend below the glidepath between ZZZZZ1 and ZZZZZ2 which may have caused us to descend below the 4;600 feet restriction at ZZZZZ1. ATC announced a terrain alert and upon realizing we were below the glidepath the First Officer disconnected the autopilot and returned to the glidepath where we continued the approach and were stabilized by every stabilized gate. The event occurred while we were VMC. The cause of this event was task saturation and failure to timely identify when the aircraft was back on vertical profile in order to re-select VNAV. Contributing factors were external distractions from unclear instructions from ATC and multiple changes during a high-workload phase of flight. Suggestions to avoid recurrence of this event would be to create more time to adequately brief and set up the aircraft for the approach to be flown; and to prioritize the use of VNAV to comply with published step-down fixes.
Second reporter narrative
ATIS was current at ZZZ...landing RWY XY. The captain was pm and asked for RNAV RNP RWY XY from ZZZZZ from ATC. ATC said 'do you want the vectors for downwind visual to RWY XY?'...I told the Captain no. Then ATC said we will have to hold at ZZZZZ and captain said that was fine. We were not issued a full holding clearance...just 'hold on the localizer'. Then ATC called back and said 'hold at 7000 at ZZZZZ'. The clearance was a bit confusing and we could not find the hold in the FMS. There is no hold published on the ILS RWY XX approach plate. Then they cleared us for the ILS RWY XX approach while we were approaching ZZZZZ; to hold northwest; at 7;000 feet. Even though ATIS was still advertising RWY XY in use. Immediately I was above the approach path and we needed to slow down and descend. I was behind the aircraft at this point. In order to descend and slow down; we put out full boards and began a much bigger rate of descent towards the glide slope. Then I selected FPA; called for gear down and flaps 3. This gave us a bigger rate of descent and deceleration desired to intercept the glideslope. While descending; ATC made us aware that a citation was landing opposite direction to RWY XY. While descending and attempting to slow down and configure the aircraft for a stable approach by the FAF ZZZZZ2; I glanced down at the chart and saw 3900' step down to ZZZZZ2. As we continued to descend rapidly I knew that I could level at 3;900 feet and this would help slowing down. However; in FPA; I was not altitude protected and may have descended below 4;600 feet at ZZZZZ1; the step-down fix prior to the final approach fix. The Captain told me to level off and I did. We intercepted the glideslope and I armed the approach. We were stable and properly configured before the FAF. We received clearance to land and taxied to the ramp after exiting RWY XX. I was behind the aircraft from the confusion with instructions to hold. The Captain realized I was task saturated and continued to make suggestions and draw my attention to importance of getting on the vertical path. I was task saturated; I was behind; and was fixed on getting down; slowing down; and being properly configured. I used FPA incorrectly and was not altitude protected at ZZZZZ1; the step down fix. Ask ATC for a delay vector in the future or I will tell the Captain I am task saturated and want to terminate the approach and request vectors to get caught up.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.