(Courtesy PBYCIA)

The engineer's "tower" in the cabane strut where the Flight Engineer monitors engine and fuel guages, operates mixture controls, starts engines, manages cowl flaps, wing tip floats, and acts as observer through the side windows.  The side windows were mainley used for monitoring the engines, but some PBY veterans wrote that this didn't mean that the side windows were not used to observe the enemy! Look down and you see the rest of the Flight Engineer's compartment.