Regional Jet 200 ER/LR (CRJ200)
Flight Crew Commercial
Workload; Communication Breakdown; Confusion
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Other / Unknown
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Chart Or Publication; Procedure
We were diverting to SPS after our destination closed due to weather. ATC instructed us to proceed direct to SPS and we advised ATC we were planning on executing the ILS to Runway 33L. As we got approximately 30 miles away we were cleared direct to the final approach fix ATRLL for the ILS. The Controller cleared us to 3;100 FT; and cleared us for the ILS; but the glideslope intercept at ATRLL is 2;300 FT. We concluded that he must expect us to do the full procedure. As we approached ATRLL the Controller asked if we were established; the Captain responded 'negative; we are about to enter the procedure turn;' the Controller came back with 'procedure turn approved.' We approached ATRLL from the direction of BOWIE VOR at 180 KTS; turned left to enter the procedure turn; [and] began the descent to 2;500 FT. As we crossed the localizer outbound preparing to bank right for the turn inbound; the Controller instructed us to return to 3;100 FT. We told him we were on the approach but he came back saying we couldn't go lower than 3;100 FT. We climbed back to 3;100 FT until established inbound and continued the approach.  We should have clarified what the Controller wanted prior to executing the approach. Our conclusions were based on believing the Controller did not make a mistake. If we had told him the glideslope was at 2;300 FT at ATRLL; not 3;100 FT; he may have revised his instructions and we wouldn't have had to do the full procedure. Effective communication is vital; we should have attempted to clarify the Controller's intentions.
An air carrier flight crew assigned 3;100 FT on a vector to SPS Runway 33L ILS began a descent to 2;500 FT as they entered the procedure turn but were told by ATC to maintain 3;100 FT on the outbound leg.