Glacier,
His english should be better than your chinese. English is the standard language of air traffic control.
Neptunus Rex has an anecdote that I have also heard when I was at Toulouse. The chinese pilots were expert at flying and knew no english. The interpreter was expert at english and knew nothing about flying. The instructors had to explain a lot to the interpreters so that they could 'explain' what was required to the pilots. I understand it was quite frustrating at times.