I got back from EZE just a couple of weeks ago. My routing was MEX-PTY-EZE and return. I have just posted two trip reports in the trip reports forum (one for the outbound and another for the return). Perhaps you may find them useful for your upcoming trip to EZE.

If you have any questions regarding Copa's (loong) flight to EZE, please feel free to ask me.

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Saludos,
El_Chilango