Can't really tell if the MAV is in a suspicious spot or up the escalator side of C? Sorry but I don't play Metro much so I'll let others chime in before taking action.
We found the spot about a month and a half ago. It's on C, you throw a Mav on top of the soda machine, climb on the machine, then jump on the Mav, from there, you jump on to the sign. Once you're on teh sign you just just straight up once and you're in to the ceiling. Don't have a screen shot to show him up there, but this shows intent to get in there as he IS standing on his mav in the middle of a fire fight.
It's kinda hard to make out with the blurring as the black-and-white MAV blends in quite well with the black-and-white train behind it. But that's the rough outline; you can see one of the white cylinders fairly well with the black body beneath it.