Gaps between maps - High Zoom Map Render Boundary Mask
Some times when zooming in a map you might see a 'black' gap between different maps. This black outline is the boundary between different map zooms - its a function of our map engine and the mask for each raster file layer, which only becomes visible at larger than native scale. It is normal for how we render our maps and not designed to be seen unless the user zooms in to a map size which is larger than what the paper map would be. When you have the Open Street Map (background map) downloaded you may see that map instead of the black (until you zoom in past the maximum for the OSM), but it depends on the situation.
Because the gap only becomes visible at greater than native scale (when you zoom in to make the map bigger than if you had a paper version sitting next to it), the decision was made not to conduct an extensive re-write of the map engine. This characteristic isn't really an issue when OzRunways is used on the iPad. However, on an iPhone users are likely to see it much more often due to the smaller screen size and how that interacts with 'native zoom', thus the resulting propensity to zoom in more and encounter the map merge boundary more often. It helps to keep in mind the OzRunways app is designed for the iPad and not the iPhone.
Users who are vision impaired and like to zoom in more than native scale may notice the map render gap more often. Users should remember that none of the information is clipped from the most zoomed layer, though the outer layers a section of detail may be lost until the map is zoomed out slightly. All maps are available at greater than native scale to assist those who like to zoom in to assist with readability.