Analysis of Magnetic Anomaly Maps and Navigation Performance Using Flight Test Data

Magenetic anomaly navigation relies on high quality maps to navigate well. The map creation process is complex and involves making decisions about where to place the sensors, how to process magnetic data, how to apply map leveling, and how wide the survey lines need to be. This work examines six magnetic maps produced by NGA which differ in leveling method (unleveled, leveled, and microleveled) and survey line spacing to determine what makes a good magnetic anomaly map for navigation. We first examine and compare the anomaly maps to understand how each map differs from the others. We find the unleveled maps to differ the most from the leveled maps, with a mean difference of 6.5 nT between the unleveled and leveled map. The average difference between the values of the leveled and microleveled maps is 0.72 nT. After examining the difference maps, the navigator is leveraged to compare navigation performance of each map across four different flights. The Distance Root Mean Square (DRMS) is calculated and compared for each separate flight using each of the six maps. The nagivation results reveal significant differences in navigation performance between the unleveled maps and the leveled and microleveled maps, especially at lower atltitudes. The leveled and microleveled both have good performance with the performance of the leveled maps being better overall. Spacing of the survey lines also has an impact on navigation performance. The grids with 1km spacing in the northern region are shown to perform better than the grids with 2km spacing.