Date: 202011
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class D ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Time Pressure; Distraction
Anomaly: ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Contributing factors: Procedure
Primary problem: Procedure

Narrative: I was operating as First Officer and Pilot Monitoring on our flight. In cruise approximately 15-20 mins prior to touchdown we were talking to Center. When we checked in with them they advised us to expect the visual for Runway XX. Being night time; we advised them that we needed the ILS. The controller then cleared us to ZZZZZ to do the NDB procedure turn for the ILS [Runway] XX. We told the controller that we couldn't find this in our box and asked for direct to ZZZZZ1 which would eliminate the procedure turn and give us more space to set up for the approach. The controller asked us why we couldn't just tune in the NDB and fly it. We ended up just asking for direct to the field while we looked at the box and tried to set up what the controller was asking. We were approved as requested. Still having trouble setting up the box we asked the controller for direct ZZZZZ1 several times for the ILS [Runway] XX. He finally cleared us direct ZZZZZ1. We were told to descend and maintain 4;100 feet until established on a segment and then cleared for the ILS [Runway] XX. Being at 4;100 feet so close in left us a little high for the approach. Approximately 1-1.5 miles from ZZZZZ1 and approaching on a 300 heading; the Captain disconnected the auto pilot. I reminded him that we were instructed to maintain 4;100 feet until established and that we were cleared for the ILS. The Captain was navigating in pink needles and I had green needles on my side so that the Captain could reference the glide slope. We were showing approximately a dot and a half above the glide slope. At that point the Captain began to descend to catch up to the glide slope and proceeded to turn inbound. As far as I could tell he started doing this prior to being established inbound. Once we were finally established inbound we were at approximately 3;800 feet and descending which was above the minimum altitude for that segment however we were instructed to maintain 4;100 feet until established on a segment. At this point the controller switched us over to advisories. The flight continued normally. The controller did not advise us of any issues. This was all under visual conditions. I don't believe the altitude was a problem. I think we were within the normal tolerances for being established on the inbound course however I am uncertain. This report is being filed because the Captain prematurely descended below our assigned altitude as well as both the Captain and I feeling as though the controller was very unprofessional and unhelpful in aiding us in flying the plane the safest way possible. The Captain and I realized that we couldn't find the appropriate fix for the procedure turn in the box and did the right thing by telling the controller and trying to work with him. He was not very receptive to helping. As I said this created confusion in the cockpit trying to figure out how to make the procedure turn happen. As mentioned; after asking several times we were finally cleared direct ZZZZZ1. Approaching ZZZZZ1 at 4;100 feet and seeing we were high; the Captain disconnected the autopilot and started descending. That's when I reminded him that we needed to maintain 4;100 feet until established and weren't quite at ZZZZZ1 yet. He responded by saying he had the field and that it was ok to start descending. The root cause of all of this was the controller refusing to accommodate our requests to start the ILS [Runway] XX at a fix that would eliminate an NDB procedure turn. All of the back and forth created a lot of confusion for us in the cockpit. The end result was us getting a compromise for flying the approach we needed however it left us high which lead the Captain to descend early to catch the glide slope. As mentioned we reacted by asking the controller several times to work with us. We weren't asking for much. All we wanted was to be cleared to a fix to give us space to set up and [eliminate] the procedure turn. As far as the Captain possibly starting his descent early; I reacted by speaking up and telling him that I didn't think we were established inbound yet. He elected to continue to descend despite the concerns. This was a one leg day. Day one of a four day trip. Starting your first leg at XA:00 is tough for anyone. Being tired from sitting around all day waiting to go to work; we figured the safest option was to ask for a solution that eliminated the NDB procedure turn. We were both confused in trying to set up the box and asked for a different fix; ZZZZZ1; which seemed like a good option. This was the right decision. We did not expect so much push back from the controller. The last time I did any NDB procedures was almost five years ago in a simulator. With GPS waypoints and our FMS; the safest option was to avoid trying to experiment with an NDB procedure turn while conducting a revenue flight at night. Additionally; although instructed to be at 4;100 feet at ZZZZZ1 which would leave us slightly high; it would have been a better option if the Captain had let the auto pilot turn inbound and as soon as we were established then he could have initiated the descent to catch up to the glide slope. This way there would have been no question about our altitude.




Synopsis: First Officer reported controller failure to understand pilots request resulted in pilot descent from assigned altitude due to clearance confusion.