Date: 201811
Local time of day: 0001-0600
Location: CKB.Airport, WV
Flight conditions: Marginal
Weather elements / visibility: Icing
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class D CKB
ATC / advisory: TRACON CKB
Reporter organization: Air Carrier
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Confusion; Situational Awareness; Communication Breakdown
Second reporter function: Pilot Not Flying; First Officer
Anomaly: ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Other / Unknown; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Terrain Warning
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: During descent for the ILS 21 KCKB; We leveled at 4;500 MSL. In the descent; ATC requested flight and icing conditions; which we reported Moderate Mixed Icing from 5;500 to 4;500 MSL with the Outside Air Temperature. ATC acknowledged our report and cleared us to descend 2;500 MSL as we were vectored southeast of the Final Approach Course for ILS 21. The Pilot Monitoring read back the 2;500 MSL assignment to ATC. Upon 3;000 MSL; we received a Terrain Caution. I immediately disconnected the Auto Pilot and began a climb. At the same time; ATC advised us to maintain 3;500 MSL. The Pilot Monitoring read back 3;500 MSL; and queried as to our original clearance down to 2;500 MSL. ATC repeated 3;500 MSL at this time; at which the Pilot Monitoring repeated once more 3;500 MSL. We were then given a southwesterly heading to join the Final Approach Course for ILS 21 and to maintain 3;000 MSL until established; and were cleared the ILS 21. Once more; the Pilot Monitoring verified 3;000 MSL; until established; which ATC confirmed 3;000 MSL. Upon intercepting the Final Approach Course; we continued the Approach to landing Runway 21 with no further incident. Poor communication; and annunciation by ATC. The clearance to 2;500 MSL was heard; confirmed; and verified by myself and the First Officer. The First Officer repeated the clearance of our descent to 2;500 MSL to ATC with no further correction as to our read back by ATC. When we read back 2;500 MSL to ATC; we should have been corrected at that time and to maintain 3;500 MSL. After debriefing the set of events that occurred when parked at the gate; I reviewed the fixes and altitudes on the ILS 21 Approach Chart. In review; the Glide Slope Intercept Altitude at ARCAT is 2878 feet MSL. I should have denied the descent to 2;500 MSL; since that was below the Glide Slope Intercept Altitude at ARCAT. By denying that descent clearance; we would have avoided this incident despite poor communication procedures by ATC.


Second narrative: [Report Narrative Contained No Additional Information.]


Synopsis: CRJ-200 flight crew reported a miscommunication with ATC led to a GPWS terrain warning.