EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness; Workload
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors; Procedure
After passing CAMRN on the CAMRN4 arrival into JFK; we were given vectors to ILS 4L. We hadn't briefed 4L; as they were using that runway for departures; and we expected 4R. After passing CAMRN; we were given several altitude; speed; and heading vectors in a short amount of time; and were finally told 'Maintain 3;000 feet until established; cleared ILS 4L Approach.' My role at the time was PM (Pilot Monitoring); and I was heads down loading the approach; briefing the briefing strip to the PF (Pilot Flying); and answering radio calls. When we were given the clearance; I failed to recognize the altitude restriction outside of AROKE on the approach was 2;000 feet; which I believed to be 3;000 feet. I also failed to recognize we were not in VNAV; but in green FLCH. The PF set 1;500 feet; which is the glide slope intercept altitude at KRSTL; and the aircraft descended below 3;000 feet. NYC Approach advised us that we were below the assigned altitude; that there was another aircraft landing 4R; and to return to 3;000 feet immediately. I then took the controls; disconnected the autopilot; climbed back to 3;000 feet; intercepted the localizer and flew the approach with no further issues. The main cause for this event was task saturation. Had we briefed both approaches and had fewer vectors before being cleared; I would have seen that we were not ASEL-ing at 3;000 feet; and that the altitude outside of AROKE was 2;000 feet. In addition; I would have seen that VNAV was not engaged. A contributing factor to this event was the runway assignments given to the aircraft involved. We were approaching JFK from the southeast; and were given 4L; on the western side; while another aircraft was approaching JFK from the southwest; and was given 4R; on the eastern side. This event has taught me that when I'm feeling task saturated to delegate tasks to the other pilot. I could have easily given the radio communications to my FO (First Officer); allowing me to devote more attention to both motoring the flight path and setting up the approach. In the future; I will take this experience and apply it in other task-heavy situations.
ERJ-175 Captain reported descending below charted altitude on approach to JFK when they got a runway assignment they weren't prepared for.