Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 180
Confusion; Situational Awareness; Communication Breakdown
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance
Human Factors
On arrival into PDX we were with Approach Control; who give us direct to the OMMSI fix; off the arrival and toward an approach fix. He then gave us; as I best recall; descend to 2;500 ft. We descended. He then; at just passing 4;000 ft; communicated in a flustered way to verify we have terrain in sight and to stop our descent. Or slow it; I really wasn't sure the meaning behind this communication; as we were descending; in perfectly clear daytime and have zero warnings. Our radar altimeter has not even populated which means we were 2;500+ feet above any terrain and we had all terrain and the airport in sight.He clarified to us our last clearance received. He thought it was 5;300 ft. We could not exactly verify that as I had adjusted the altitude window to higher than 2;500 ft to stop a descent; but it was definitely not 5;300 ft assigned. Had we continued closer on our way towards 2;500 ft I'm sure we would have questioned things as well. He noticed an error from alerts on his end I'm sure; and we were on our way to noticing incorrect happenings; also. If anything; this was just a pure accidental clearance given earlier than planned. We may have been off the vertical safety course for a bit but this sort of accidental clearance issuance is more based in being human than gross negligence. I suppose briefing more MSA (Minimum Safe Altitude) in relation to position of approaches/arrivals could be useful; but it was clear and I routinely get clearances to descend lower than other IFR segments on approach courses. I don't know what else to say really. He caught himself and checked we were seeing what we were doing. Good.
FO (First Officer) was flying. We were taken off the arrival and cleared direct to a fix on the approach. Then given a further descent to 2;500 ft. I read back 2;500 ft about 4;000 ft; Approach in a panicked voice asked if we saw the field; which I replied affirmative. He then cleared us for the visual and asked us to arrest our descent and if we see the terrain. I said we did. He said our clearance was only to 5;300 ft and he asked again if we saw the terrain. I replied we did and were Visual to 28R. There were no terrain warnings in the cockpit; nor was the RA (Resolution Advisory) registering terrain at that time. We didn't feel there was a threat to the aircraft and landed uneventfully on 28R. When Approach cleared us to 2;500 ft and I read back 2;500 ft is when the error should have been caught.
Air carrier flight crew received erroneous descent clearance inflight from Air Traffic Control.