Commercial Fixed Wing
Workload; Situational Awareness; Human-Machine Interface; Communication Breakdown; Confusion
ATC Issue All Types; Deviation - Altitude Undershoot; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Software and Automation; Human Factors; Procedure
Received numerous ATC clearances via CPDLC while enroute. First cleared us down to 38;000 ft; was accepted by Pilot Flying.. Next was a route clearance. First line of free text said 'Cleared to NIKLS'. Pilot Flying changed the Legs page with verification from me. After a few minutes ATC sent another CPDLC that said descend to 34;000 ft and then another clearance came in a couple moments later clearing us to 31;000 ft. ATC then queried via radio '(Call sign) where are you heading direct to?' I answered NIKLS and was told that is not your clearance and was given an immediate heading. We then brought up our clearance and noticed the next line of free text said 'VIA LAYED FARLN NIKLS'. ATC then read this clearance and asked what altitude we were cleared down to. We noticed that the aircraft had stopped at 34;000 ft while we figured out our navigation error. We then descended to 34;000 ft and proceeded on the correct route.
While descending to 34;000 ft we received a CPDLC clearance to proceed direct to NIKLS VIA and then the rest of the clearance. We did not see the VIA part. We went direct to NIKLS. Then we received a descend to 31;000 ft. While still in the descent; ATC asked if we were going direct to NIKLS. We said yes. ATC said that we were not cleared direct. They gave us a heading; and verbally gave us the other fixes that came before NIKLS. As we were writing down the clearance; the plane leveled off at 34;000 ft. ATC asked if we were cleared to 31;000 ft. We said yes; and started to descend to 31;000 ft.
A Flight Crew reported a course deviation and failure to descend due to confusion recieving multiple CPDLC clearances from ATC.