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.

Google
 

Original NASA ASRS Text

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

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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.