MD-82
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Other / Unknown
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Aircraft; Weather
Climbing out to FL340; aircraft stopped climbing at FL327; Mach .740 decreased to Mach .730. We requested descent to FL320. Aircraft began descent in IAS/MACH to FL325 before clearance received. ATC comment was that we were already descending to FL320; and then he gave us the clearance. We told ATC it was due to icing and aircraft performance. Performance charts indicated that a climb to FL340 with anti-ice on was OK. Light rime ice on windshield wiper nut and light turbulence.
[Narrative #2 contained no additional information]
An MD82 climbing to FL340 with anti-ice began an uncommanded descent at FL327 because of poor aircraft performance and so requested a descent to FL320.