Challenger 300
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Human Factors
We were descending into Milan and talking to the Center just prior to the Approach Controller. The pilot not flying asked that I take over the radio while he picked up ATIS. The Controller issued what I understood to be the instruction 'descend to 310 - eleven at TIRUL.' Controller had a strong Italian accent. I asked him to repeat the instructions. I read back to the Controller; 'Descend to 310 - eleven at TIRUL.' I was not sure of the exact fix so I spelled it phonetically. He then again read the instructions to what I thought was - descend to 310 - 11;000 at TIRUL. I again acknowledged. When passing through FL300 the Controller asked what my assigned altitude was. When I told him 11;000 at TIRUL he said; 'No; assigned altitude is 310; climb back to 310.' We immediately climbed back to that altitude; after analyzing the Controller most likely said to descend to 310 - level at TIRUL. The word 'level' and 'eleven' sounded very similar with his accent. We did not see any other aircraft on TCAS and asked the Controller if everything was okay and he said there was no problem. He then gave us a change of frequency to another sector and we continued our descent into Milan. It's important to realize there's going to be language barriers and phraseology differences when flying in foreign countries. You must be aware of this and double check on any instructions. This is even more important when the other crew member is performing other duties.
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CL300 flight crew misinterpreted descent instruction due to Italian Controller's accent.