Per the manual, the NAV RAD button is used for specifying VORs and ADFs. What I don't understand is how this information is used. How can these stations be used for navigation ? Are they supposed to be used for actual navigation or are they informational only ? Unlike other aircraft, there is no NAV function for capturing the course (CRS) specified in the NAV1 radio (I am aware of PB/D waypoints, etc., and their use in the FMC).I would appreciate some guidance for the FMC's NAV RAD button.Zach

They are used for Raw navigation due to IRS drift (would you trust the map display 100% on a CATIII3B Approach?) also they are used to partialy update the FMC. This is a very basic answer and I'm sure someone else will give you more info.Rob

Read the AOM (Pg 7-4 Navigation Radios). You can use the VOR for navigation but the primary use is for FMC calculation of position along with the other sources.