@NonNull
    private static App getDefaultNavigationApplication(final int defaultNavigation) {
        if (defaultNavigation == 2) {
            return getNavigationAppForId(Settings.getDefaultNavigationTool2());
        }
        return getNavigationAppForId(Settings.getDefaultNavigationTool());
    }
Starts the default navigation tool if correctly set and installed or the compass app as default fallback.
main/src/main/java/cgeo/geocaching/apps/navi/NavigationAppFactory.java