Our American Airlines 707's had just a single column one on the forward edge of the FE panel. It was the Challange / Responce check list for takeoff and landing. Once the FE got the answer for each question, the slide went the other way for the next takeoff or landing. Very simple to use.
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This is the first time I have seen one in a two person cockpit. Center location makes sense, but does it block your view in flight?