I have a question for GA autopilot.say.. I have a flight plan and I click on the AP NAV. and its now tracking the Nav course. (It doesn't matter if the course is a VOR or a GPS). I understand how that works.Now, Say.. I select from the GPS an approach the airport. ILS 18R into DFW and make it active.The nav function seems to follow that approach course...so..1. what do I do with that APR button of the autopilot? 2. When do I select that? 3. when I select APR, do I stll have to have the NAV selected as well? Is it mutually exclusive?4. What does APR add to the value? What I am getting at is..NAV seems to do the approach... Manny

NAV mode says "Follow that nav source". BUT GPS or NAV mode says what source that is - radio navigation or global positioning. APR is APProach and is a more sensitive device than NAV, and can also include glideslope information as well as localiser.So you use GPS or NAV to establish yourself on either the localiser, or an intercept course to it, then switch the `source` to NAV from GPS mode if necessary, then switch the a/p to APR tro acquire the localiser and/or the glideslope.Hope this helps but there's more info herehttp://www.navfltsm.addr.com/ils.htmAllcott

Thank you Allcott.Tried it out..worked as explained.;)