The missing aviators, if they lacked both a map and a name for their island, obviously might attempt to communicate their location by determining geographical coordinates, or proximity to other islands etc. I have sometimes enjoyed speculating that they might also have attempted to describe the shape of the island itself.
I was intrigued by the reference in Betty's notebook, page 53, to 'Fig 8', because from certain viewpoints Niku looks a bit like a figure 8. Well, I think so anyway! From low elevations and an appropriate viewing angle the point of land which extends into the lagoon near the top of Aukaraime North visually "comes close to" Bauareke Passage, thus one may perceive a lagoon in two parts partly separated by land.
I wonder if amongst the confusion of words and numbers Betty's half-heard snippet records an attempt by Earhart to describe the island's shape. Clearly there is nothing to be proven here. But its fun to speculate. The visual trick only works from some viewing positions, and not from others.
I encourage readers with Google Earth to have a little fly around and see what they think. I also wonder what that very select group of people who have actually seen Niku from the air think about my Figure 8 hypothesis.