What is localizer course preview? It's a white navigation line that shows you the actual deflection of the localizer while you're still navigating using RNAV. This course preview feature satisfies the AIM's requirement of raw localizer data when navigating up to the final approach fix of an ILS or localizer-only approach (AIM 1-2-3 (c) Note 2). As you approach the FAF, most systems will automatically switch from magenta to green needles. #aviation #pilot #avgeek #ILSApproach #GreenNeedles #IFRTr